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publications.bib
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@article{schwefel_dramatic_2004,
title = {Dramatic shape sensitivity of directional emission patterns from similarly deformed cylindrical polymer lasers},
volume = {21},
url = {http://josab.osa.org/abstract.cfm?URI=josab-21-5-923},
doi = {10.1364/JOSAB.21.000923},
note = { citations $\geq$ 217},
abstract = {Recent experiments on similarly shaped polymer microcavity lasers show a dramatic difference in the far-field emission patterns. We show, for different deformations of the ellipse, quadrupole and hexadecapole, that the large differences in the far-field emission patterns are explained by the differing ray dynamics corresponding to each shape. Analyzing the differences in the appropriate phase space for ray motion, it is shown that the differing geometries of the unstable manifolds of periodic orbits are the decisive factors in determining the far-field pattern. Surprisingly, we find that strongly chaotic ray dynamics is compatible with highly directional emission in the far field.},
number = {5},
journal = {Journal of the Optical Society of America B},
author = {Schwefel, Harald G. L. and Rex, Nathan B. and Türeci, Hakan E. and Chang, Richard K. and Stone, A. Douglas and Ben-Messaoud, Tahar and Zyss, Joseph},
month = may,
year = {2004},
keywords = {chaos, Laser resonators, Lasers, solid-state, micro-optics, Optical resonators},
pages = {923--934}
}
@ARTICLE{RexTSCS02,
author = {Rex, Nathan B. and T\"ureci, Hakan E. and Schwefel, Harald G. L.
and Chang, Richard K. and Stone, A. Douglas},
title = {Fresnel filtering in lasing emission from scarred
modes of wave-chaotic optical resonators},
journal = {Physical Review Letters},
year = {2002},
volume = {88},
pages = {094102},
url= {http://link.aps.org/abstract/PRL/v88/e094102 },
doi = {10.1103/PhysRevLett.88.094102},
note = { citations $\geq$ 148},
abstract = {We study lasing emission from asymmetric resonant
cavity GaN microlasers. By comparing far-field intensity patterns
with images of the microlaser we find that the lasing modes are
concentrated on three-bounce unstable periodic ray orbits; i.e.,
the modes are scarred. The high-intensity emission directions of
these scarred modes are completely different from those predicted
by applying Snell's law to the ray orbit. This effect is due to the
process of "Fresnel filtering" which occurs when a beam of finite
angular spread is incident at the critical angle for total internal
reflection.
}
}
@article{peng_broadband_2010,
title = {Broadband {NIR} photoluminescence from Bi-doped {Ba$_2$P$_2$O$_7$} crystals: Insights into the nature of {NIR-emitting} Bismuth centers},
volume = {18},
shorttitle = {Broadband {NIR} photoluminescence from Bi-doped {Ba2P2O7} crystals},
url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-18-12-12852},
doi = {10.1364/OE.18.012852},
abstract = {We report on a novel type of Bi-doped crystal that exhibits ultrabroadband photoluminescence in the near infrared {(NIR).} Emission centers can be generated and degenerated reversibly by annealing the material in {CO} atmosphere and air, respectively, indicating that emission is related to the presence of Bi-species in low valence states. Correlating static and dynamic excitation and emission data with the size and charge of available lattice sites suggests that two types of Bi0-species, each located on one of the two available Ba2+ lattice sites, are responsible for {NIR} photoemission. This is further confirmed by the absence of {NIR} emission in polycrystalline {Ca2P2O7:Bi} and {Sr2P2O7:Bi.} Excitation is assigned to transitions between the doubly degenerated ground state {4S3/2} and the degenerated excited levels {2D3/2}, {2D5/2} and {2P1/2}, respectively. {NIR} emission is attributed to {2D3/2→4S3/2.} The {NIR} emission center can coexist with Bi2+ species. Then, also Bi2+ is accommodated on one of the two Ba2+-sites. Energy transfer between Bi2+ ions occurs within a critical distance of 25.9 Å.},
number = {12},
journal = {Optics Express},
author = {Peng, Mingying and Sprenger, Benjamin and Schmidt, Markus A. and Schwefel, Harald G. L. and Wondraczek, Lothar},
month = jun,
year = {2010},
keywords = {Fluorescent and luminescent materials, Laser materials, Optical amplifiers, optical materials},
pages = {12852--12863},
note = {citations $>$ 123},
file = {Opt. Express Snapshot:/Volumes/Macintosh HD/Users/harry/Library/Application Support/Firefox/Profiles/vn6sgh2i.default/zotero/storage/PSWTDWSM/abstract.html:text/html;OSA Journals PDF:/Volumes/Macintosh HD/Users/harry/Library/Application Support/Firefox/Profiles/vn6sgh2i.default/zotero/storage/26NAGNTH/view_article.html:text/html;Peng et al. - 2010 - Broadband NIR photoluminescence from Bi-doped Ba2P.pdf:/Volumes/Macintosh HD/Users/harry/Library/Application Support/Firefox/Profiles/vn6sgh2i.default/zotero/storage/PZQHCB5T/Peng et al. - 2010 - Broadband NIR photoluminescence from Bi-doped Ba2P.pdf:application/pdf}
}
@ARTICLE{CarmonSYOSV08,
author = {Tal Carmon and Harald G. L. Schwefel and Lan Yang and
Mark Oxborrow and A. Douglas Stone and Kerry J. Vahala},
title = {Static envelope patterns in composite resonances
generated by level crossing in optical toroidal microcavities},
journal = {Physical Review Letters},
year = {2008},
volume = {100},
pages = {103905},
note = { citations $\geq$ 98},
url= {http://link.aps.org/abstract/PRL/v100/e103905 },
doi = {10.1103/PhysRevLett.100.103905},
abstract = {We study level crossing in the optical
whispering-gallery (WG) modes by using toroidal microcavities.
Experimentally, we image the stationary envelope patterns of the
composite optical modes that arise when WG modes of different
wavelengths coincide in frequency. Numerically, we calculate
crossings of levels that correspond with the observed degenerate
modes, where our method takes into account the not perfectly
transverse nature of their field polarizations. In addition, we
analyze anticrossing with a large avoidance gap between modes of
the same azimuthal number.
}
}
@article{strekalov_nonlinear_2016,
title = {Nonlinear and quantum optics with whispering gallery resonators},
volume = {18},
issn = {2040-8986},
url = {http://stacks.iop.org/2040-8986/18/i=12/a=123002},
doi = {10.1088/2040-8978/18/12/123002},
abstract = {Optical whispering gallery modes (WGMs) derive their name from a famous acoustic phenomenon of guiding a wave by a curved boundary observed nearly a century ago. This phenomenon has a rather general nature, equally applicable to sound and all other waves. It enables resonators of unique properties attractive both in science and engineering. Very high quality factors of optical WGM resonators persisting in a wide wavelength range spanning from radio frequencies to ultraviolet light, their small mode volume, and tunable in- and out- coupling make them exceptionally efficient for nonlinear optical applications. Nonlinear optics facilitates interaction of photons with each other and with other physical systems, and is of prime importance in quantum optics. In this paper we review numerous applications of WGM resonators in nonlinear and quantum optics. We outline the current areas of interest, summarize progress, highlight difficulties, and discuss possible future development trends in these areas.},
number = {12},
urldate = {2016-12-05},
journal = {Journal of Optics},
author = {Strekalov, Dmitry V. and Marquardt, Christoph and Matsko, Andrey B. and Schwefel, Harald G. L. and Leuchs, Gerd},
year = {2016},
month = nov,
note = { citations $\geq$ 278},
pages = {123002}
}
@article{tureci_gaussian-optical_2002,
title = {Gaussian-optical approach to stable periodic orbit resonances of partially chaotic dielectric micro-cavities},
volume = {10},
doi = {10.1364/OE.10.000752},
url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-10-16-752},
abstract = {The quasi-bound modes localized on stable periodic ray orbits of dielectric micro-cavities are constructed in the short-wavelength limit using the parabolic equation method. These modes are shown to coexist with irregularly spaced �??chaotic�?? modes for tHarald G.neric case. The wavevector quantization rule for the quasi-bound modes is derived and given a simple physical interpretation in terms of Fresnel reflection; quasi-bound modes are explictly constructed and compared to numerical results. The effect of discrete symmetries of the resonator is analyzed and shown to give rise to quasi-degenerate multiplets; the average splitting of these multiplets is calculated by methods from quantum chaos theory.},
number = {16},
journal = {Optics Express},
author = {Türeci, Hakan E. and Schwefel, Harald G. L. and Stone, A. Douglas and Narimanov, Evgeniy},
year = {2002},
keywords = {Laser resonators, Mathematical methods (general), Optical resonators},
pages = {752--776},
note = { citations $\geq$ 77, Cover Article}
}
@article{rueda_efficient_2016,
title = {Efficient microwave to optical photon conversion: an electro-optical realization},
volume = {3},
copyright = {© 2016 Optical Society of America},
issn = {2334-2536},
shorttitle = {Efficient microwave to optical photon conversion},
url = {http://www.osapublishing.org/abstract.cfm?uri=optica-3-6-597},
doi = {10.1364/OPTICA.3.000597},
abstract = {Linking classical microwave electrical circuits to the optical telecommunication band is at the core of modern communication. Future quantum information networks will require coherent microwave-to-optical conversion to link electronic quantum processors and memories via low-loss optical telecommunication networks. Efficient conversion can be achieved with electro-optical modulators operating at the single microwave photon level. In the standard electro-optic modulation scheme, this is impossible because both up- and down-converted sidebands are necessarily present. Here, we demonstrate true single-sideband up- or down-conversion in a triply resonant whispering gallery mode resonator by explicitly addressing modes with asymmetric free spectral range. Compared to previous experiments, we show a 3 orders of magnitude improvement of the electro-optical conversion efficiency, reaching 0.1\% photon number conversion for a 10 GHz microwave tone at 0.42 mW of optical pump power. The presented scheme is fully compatible with existing superconducting 3D circuit quantum electrodynamics technology and can be used for nonclassical state conversion and communication. Our conversion bandwidth is larger than 1 MHz and is not fundamentally limited.},
number = {6},
urldate = {2016-06-05},
journal = {Optica},
author = {Rueda, Alfredo and Sedlmeir, Florian and Collodo, Michele C. and Vogl, Ulrich and Stiller, Birgit and Schunk, Gerhard and Strekalov, Dmitry V. and Marquardt, Christoph and Fink, Johannes M. and Painter, Oskar and Leuchs, Gerd and Schwefel, Harald G. L.},
month = jun,
year = {2016},
note = { citations $\geq$ 218},
pages = {597--604}
}
@article{sprenger_whispering-gallery-mode-resonator-stabilized_2009,
title = {Whispering-gallery-mode-resonator-stabilized narrow-linewidth fiber loop laser},
volume = {34},
url = {http://ol.osa.org/abstract.cfm?URI=ol-34-21-3370},
doi = {10.1364/OL.34.003370},
abstract = {We demonstrate a narrow-line fiber loop laser using erbium-doped fiber as gain material, stabilized by using a microsphere as a transmissive frequency selective element. Stable lasing with a linewidth of 170 {kHz} is observed, limited by the experimental spectral resolution. A linear increase in output power and a redshift of the lasing mode were also observed with increasing pump power. Its potential applications are discussed.},
number = {21},
journal = {Optics Letters},
author = {Sprenger, Benjamin and Schwefel, Harald G. L. and Wang, L. J.},
month = nov,
note = { citations $\geq$ 84},
year = {2009},
keywords = {Fibers, erbium, Laser stabilization, Lasers, fiber, Wavelength filtering devices},
pages = {3370--3372},
file = {Opt. Lett. Snapshot:/Volumes/Macintosh HD/Users/harry/Library/Application Support/Firefox/Profiles/vn6sgh2i.default/zotero/storage/Q6897BE5/abstract.html:text/html;OSA Journals PDF:/Volumes/Macintosh HD/Users/harry/Library/Application Support/Firefox/Profiles/vn6sgh2i.default/zotero/storage/2TC5DTI3/Sprenger et al. - 2009 - Whispering-gallery-mode-resonator-stabilized narro.pdf:application/pdf}
}
@article{preu_coupled_2008,
title = {Coupled whispering gallery mode resonators in the Terahertz frequency range},
volume = {16},
url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-16-10-7336},
doi = {10.1364/OE.16.007336},
abstract = {We report on coupling of two whispering gallery mode resonators in the Terahertz frequency range. Due to the long wavelength in the millimeter to submillimeter range, the resonators can be macroscopic allowing for accurate size and shape control. This is necessary to couple specific modes of two or more resonators. Sets of polyethylene (PE) and quartz disk resonators are demonstrated, with medium (loaded) quality (Q)-factors of 40-800. Both exhibit coinciding resonance frequency spectra over more than ten times the free spectral range. Loading effects of single resonators are investigated which provide strong Q-factor degradation and red-shifts of the resonances in the 0.2 range. By coupling two resonators of the same size, we observe mode splitting, in very good agreement with our numerical calculations.},
number = {10},
journal = {Optics Express},
author = {Preu, Sascha and Schwefel, Harald G. L. and Malzer, Stefan and Döhler, Gottfried H. and Wang, L. J. and Hanson, M. and Zimmerman, J. D. and Gossard, A. C.},
year = {2008},
note = { citations $\geq$ 61},
keywords = {coupling, laser, Microcavities, resonators},
pages = {7336–7343}
}
@article{fortsch_highly_2015,
title = {Highly efficient generation of single-mode photon pairs from a crystalline whispering-gallery-mode resonator source},
volume = {91},
url = {http://link.aps.org/doi/10.1103/PhysRevA.91.023812},
doi = {10.1103/PhysRevA.91.023812},
abstract = {We report a highly efficient source of narrow-band photon pairs based on parametric down-conversion in a crystalline whispering-gallery-mode resonator. Remarkably, each photon of a pair is detected in a single spatial and temporal mode, as witnessed by Glauber's autocorrelation function. We explore the phase-matching conditions in spherical geometries, and determine the requirements for single-mode operation. Understanding these conditions has allowed us to experimentally demonstrate a single-mode pair-detection efficiency of 1.13×106 pairs/s per mW pump power per 26.8 MHz bandwidth.},
number = {2},
urldate = {2015-04-10},
journal = {Physical Review A},
note = { citations $\geq$ 73},
author = {Förtsch, Michael and Schunk, Gerhard and Fürst, Josef U. and Strekalov, Dmitry and Gerrits, Thomas and Stevens, Martin J. and Sedlmeir, Florian and Schwefel, Harald G. L. and Nam, Sae Woo and Leuchs, Gerd and Marquardt, Christoph},
month = feb,
year = {2015},
pages = {023812}
}
@article{strekalov_microwave_2009,
title = {Microwave whispering-gallery resonator for efficient optical up-conversion},
volume = {80},
url = {http://link.aps.org/abstract/PRA/v80/e033810},
doi = {10.1103/PhysRevA.80.033810},
abstract = {Conversion of microwave radiation into the optical range has been predicted to reach unity quantum efficiency in whispering-gallery resonators made from an optically nonlinear crystal and supporting microwave and optical modes simultaneously. In this work, we theoretically explore and experimentally demonstrate a resonator geometry that can provide the required phase matching for such a conversion at any desired frequency in the sub-THz range. We show that such a ring-shaped resonator not only allows for the phase matching but also maximizes the overlap of the interacting fields. As a result, unity-efficient conversion is expected in a resonator with feasible parameters.},
number = {3},
journal = {Physical Review A},
author = {Strekalov, Dmitry V. and Schwefel, Harald G. L. and Savchenkov, Anatoliy A. and Matsko, Andrey B. and Wang, L. J. and Yu, Nan},
year = {2009},
note = { citations $\geq$ 71},
keywords = {microwave generation, microwave photonics, optical frequency conversion, optical materials, optical phase matching, Optical resonators, Whispering gallery modes},
pages = {033810--5}
}
@article{schunk_interfacing_2015,
title = {Interfacing transitions of different alkali atoms and telecom bands using one narrowband photon pair source},
volume = {2},
copyright = {© 2015 Optical Society of America},
issn = {2334-2536},
url = {http://www.osapublishing.org/abstract.cfm?uri=optica-2-9-773},
doi = {10.1364/OPTICA.2.000773},
abstract = {Quantum information technology strongly relies on the coupling of optical photons with narrowband quantum systems, such as quantum dots, color centers, and atomic systems. This coupling requires matching the optical wavelength and bandwidth to the desired system, which presents a considerable problem for most available sources of quantum light. Here we demonstrate the coupling of alkali dipole transitions with a tunable source of photon pairs. Our source is based on spontaneous parametric downconversion in a triply resonant whispering gallery mode resonator. For this, we have developed novel wavelength-tuning mechanisms that allow a coarse tuning to either the cesium or rubidium wavelength, with subsequent continuous fine-tuning to the desired transition. As a demonstration of the functionality of the source, we performed a heralded single-photon measurement of the atomic decay. We present a major advance in controlling the spontaneous downconversion process, which makes our bright source of heralded single photons now compatible with a plethora of narrowband resonant systems.},
number = {9},
urldate = {2015-08-25},
note = { citations $\geq$ 69},
journal = {Optica},
author = {Schunk, Gerhard and Vogl, Ulrich and Strekalov, Dmitry V. and Förtsch, Michael and Sedlmeir, Florian and Schwefel, Harald G. L. and Göbelt, Manuela and Christiansen, Silke and Leuchs, Gerd and Marquardt, Christoph},
month = sep,
year = {2015},
pages = {773--778},
file = {optica-2-9-773.pdf:/Users/hschwef/zotero/storage/AIJ232JN/optica-2-9-773.pdf:application/pdf}
}
@article{schwefel_direct_2008,
title = {Direct experimental observation of the single reflection optical Goos-Hänchen shift},
volume = {33},
url = {http://ol.osa.org/abstract.cfm?URI=ol-33-8-794},
doi = {10.1364/OL.33.000794},
abstract = {We report a precise direct measurement of the Goos-Hänchen shift after one reflection off a dielectric interface coated with periodic metal stripes. The spatial displacement of the shift is determined by image analysis. A maximal absolute shift of 5.18 and 23.39 μm for {TE} and {TM} polarized light, respectively, is determined. This technique is simple to implement and can be used for a large range of incident angles.},
number = {8},
journal = {Optics Letters},
author = {Schwefel, Harald G. L. and Köhler, Wolfgang and Lu, Z. H. and Fan, J. and Wang, L. J.},
month = apr,
year = {2008},
keywords = {Image analysis, Surface waves, Total internal reflection},
pages = {794--796},
note = { citations $\geq$ 54}
}
@article{peano_intracavity_2015,
title = {Intracavity {Squeezing} {Can} {Enhance} {Quantum}-{Limited} {Optomechanical} {Position} {Detection} through {Deamplification}},
volume = {115},
url = {http://link.aps.org/doi/10.1103/PhysRevLett.115.243603},
doi = {10.1103/PhysRevLett.115.243603},
eprint = {http://arxiv.org/abs/1502.06423},
abstract = {It has been predicted and experimentally demonstrated that by injecting squeezed light into an optomechanical device, it is possible to enhance the precision of a position measurement. Here, we present a fundamentally different approach where the squeezing is created directly inside the cavity by a nonlinear medium. Counterintuitively, the enhancement of the signal-to-noise ratio works by deamplifying precisely the quadrature that is sensitive to the mechanical motion without losing quantum information. This enhancement works for systems with a weak optomechanical coupling and/or strong mechanical damping. This can allow for larger mechanical bandwidth of quantum-limited detectors based on optomechanical devices. Our approach can be straightforwardly extended to quantum nondemolition qubit detection.},
number = {24},
urldate = {2015-12-14},
journal = {Physical Review Letters},
author = {Peano, Vittorio and Schwefel, Harald G. L. and Marquardt, Christoph and Marquardt, Florian},
month = dec,
year = {2015},
pages = {243603},
note = { citations $\geq$ 97}
}
@article{sedlmeir_high-q_2014,
title = {High-Q {MgF}$_2$ whispering gallery mode resonators for refractometric sensing in aqueous environment},
volume = {22},
url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-22-25-30934},
eprint = {http://arxiv.org/abs/1409.2539},
doi = {10.1364/OE.22.030934},
abstract = {We present our experiments on refractometric sensing with ultrahigh-Q, crystalline, birefringent magnesium fluoride (MgF_2) whispering gallery mode resonators. The difference to fused silica which is most commonly used for sensing experiments is the small refractive index of {MgF}2 which is very close to that of water. Compared to fused silica this leads to more than 50\% longer evanescent fields and a 4.25 times larger sensitivity. Moreover the birefringence amplifies the sensitivity difference between {TM} and {TE} type modes which will enhance sensing experiments based on difference frequency measurements. We estimate the performance of our resonators and compare them with fused silica theoretically and present experimental data showing the interferometrically measured evanescent field decay and the sensitivity of mm-sized MgF_2 whispering gallery mode resonators immersed in water. These data show reasonable agreement with the developed theory. Furthermore, we observe stable Q factors in water well above 1 × 10^8.},
number = {25},
note = { citations $\geq$ 85},
urldate = {2014-12-07},
journal = {Optics Express},
author = {Sedlmeir, Florian and Zeltner, Richard and Leuchs, Gerd and Schwefel, Harald G. L.},
month = dec,
year = {2014},
keywords = {Birefringence, Optical resonators, Optical sensing and sensors},
pages = {30934--30942}
}
@article{breunig_whispering_2013,
title = {Whispering gallery modes at the rim of an axisymmetric optical resonator: Analytical versus numerical description and comparison with experiment},
volume = {21},
shorttitle = {Whispering gallery modes at the rim of an axisymmetric optical resonator},
url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-21-25-30683},
doi = {10.1364/OE.21.030683},
abstract = {Optical whispering gallery modes ({WGMs)} of mm-sized axisymmetric resonators are well localized at the equator. Employing this distinctive feature, we obtain simple analytical relations for the frequencies and eigenfunctions of {WGMs} which include the major radius of the resonator and the curvature radius of the rim. Being compared with results of finite-element simulations, these relations show a high accuracy and practicability. High-precision free-spectral-range measurements with a millimeter-sized disc resonator made of {MgF2} allow us to identify the {WGMs} and confirm the applicability of our analytical description.},
number = {25},
urldate = {2013-12-05},
journal = {Optics Express},
author = {Breunig, Ingo and Sturman, Boris and Sedlmeir, Florian and Schwefel, Harald G. L. and Buse, Karsten},
month = dec,
year = {2013},
keywords = {Optical resonators, Resonators},
pages = {30683--30692},
note = { citations $\geq$ 72}
}
@article{sprenger_caf2_2010,
title = {{CaF$_2$} whispering-gallery-mode-resonator stabilized-narrow-linewidth laser},
volume = {35},
url = {http://ol.osa.org/abstract.cfm?URI=ol-35-17-2870},
doi = {10.1364/OL.35.002870},
abstract = {A fiber laser is stabilized by introducing a calcium fluoride {(CaF$_2$)} whispering-gallery-mode resonator as a filtering element in a ring cavity. It is set up using a semiconductor optical amplifier as a gain medium. The resonator is critically coupled through prisms, and used as a filtering element to suppress the laser linewidth. A three-cornered-hat method is used and shows a stability of 10−11 after 10μs. Using the self-heterodyne beat technique, the linewidth is determined to be {13kHz.} This implies an enhancement factor of 10$^3$ with respect to the passive cavity linewidth.},
number = {17},
journal = {Optics Letters},
author = {Sprenger, Benjamin and Schwefel, Harald G. L. and Lu, Z. H. and Svitlov, Sergiy and Wang, L. J.},
year = {2010},
keywords = {Fibers, erbium, Laser stabilization, Lasers, fiber, Wavelength filtering devices},
pages = {2870--2872},
note = {citations $\geq$ 53; Featured in LaserFocusWorld (10/11/2010)}
}
@article{schunk_identifying_2014,
title = {Identifying modes of large whispering-gallery mode resonators from the spectrum and emission pattern},
volume = {22},
url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-22-25-30795},
eprint = {http://arxiv.org/abs/1408.5071},
doi = {10.1364/OE.22.030795},
abstract = {Identifying the mode numbers in whispering-gallery mode resonators ({WGMRs}) is important for tailoring them to experimental needs. Here we report on a novel experimental mode analysis technique based on the combination of frequency analysis and far-field imaging for high mode numbers of large {WGMRs}. The radial mode numbers q and the angular mode numbers p = ℓ-m are identified and labeled via far-field imaging. The polar mode numbers ℓ are determined unambiguously by fitting the frequency differences between individual whispering gallery modes ({WGMs}). This allows for the accurate determination of the geometry and the refractive index at different temperatures of the {WGMR}. For future applications in classical and quantum optics, this mode analysis enables one to control the narrow-band phase-matching conditions in nonlinear processes such as second-harmonic generation or parametric down-conversion.},
number = {25},
urldate = {2014-12-05},
journal = {Optics Express},
author = {Schunk, Gerhard and Fürst, Josef U. and Förtsch, Michael and Strekalov, Dmitry V. and Vogl, Ulrich and Sedlmeir, Florian and Schwefel, Harald G. L. and Leuchs, Gerd and Marquardt, Christoph},
month = dec,
year = {2014},
keywords = {Optical resonators, Resonators},
pages = {30795--30806},
note = { citations $\geq$ 74}
}
@article{kaplan_finite_2013,
title = {Finite element simulation of a perturbed axial-symmetric whispering-gallery mode and its use for intensity enhancement with a nanoparticle coupled to a microtoroid},
volume = {21},
url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-21-12-14169},
doi = {10.1364/OE.21.014169},
abstract = {We present an optical mode solver for a whispering gallery resonator coupled to an adjacent arbitrary shaped nano-particle that breaks the axial symmetry of the resonator. Such a hybrid resonator-nanoparticle is similar to what was recently used for bio-detection and for field enhancement. We demonstrate our solver by parametrically studying a toroid-nanoplasmonic device and get the optimal nano-plasmonic size for maximal enhancement. We investigate cases near a plasmonic resonance as well as far from a plasmonic resonance. Unlike common plasmons that typically benefit from working near their resonance, here working far from plasmonic resonance provides comparable performance. This is because the plasmonic resonance enhancement is accompanied by cavity quality degradation through plasmonic absorption.},
number = {12},
urldate = {2013-06-06},
journal = {Optics Express},
note = { citations $\geq$ 50},
author = {Kaplan, Alex and Tomes, Matthew and Carmon, Tal and Kozlov, Maxim and Cohen, Oren and Bartal, Guy and Schwefel, Harald G. L.},
month = jun,
year = {2013},
keywords = {Computational electromagnetic methods, Plasmonics, Resonators},
pages = {14169--14180}
}
@article{rivera-lavado_dielectric_2015,
title = {Dielectric {Rod} {Waveguide} {Antenna} as {THz} {Emitter} for {Photomixing} {Devices}},
volume = {63},
issn = {0018-926X},
doi = {10.1109/TAP.2014.2387419},
abstract = {We propose a dielectric rod waveguide antenna (DRW) integrated with a photomixer as a THz emitter. This represents a different approach as opposed to the classical solution of a substrate lens. Main goals are an inexpensive alternative to substrate lenses, reduction of both reflections on the semiconductor-air interface and scattering of terahertz-generated power into the substrate. A radiation pattern measured at 137 GHz is shown as a proof-of-concept. In order to increase radiated power, the improvement of the rod antenna is discussed. Finally, as an application example, evanescent coupling of the DRW into a high index whispering gallery mode resonator is shown.},
number = {3},
journal = {IEEE Transactions on Antennas and Propagation},
author = {Rivera-Lavado, A. and Preu, Sascha and García-Muñoz, Luis Enrique and Generalov, A. and Montero-de-Paz, J. and Döhler, Gottfied H. and Lioubtchenko, D. and Méndez-Aller, M. and Sedlmeir, Florian and Schneidereit, Martin and Schwefel, Harald G. L. and Malzer, Stefan and Segovia-Vargas, D. and Räisänen, A. V.},
month = mar,
year = {2015},
keywords = {Antenna measurements, Antenna radiation patterns, dielectric resonators, dielectric rod waveguide antenna, Dielectric rod waveguide (DRW) antenna, Dielectrics, electromagnetic wave scattering, frequency 137 GHz, high index whispering gallery mode resonator, integrated emitter, Lenses, photomixer, photomixing devices, semiconductor-air interface, substrates, terahertz-generated power scattering, terahertz wave devices, THz antenna, THz emitter, waveguide antennas, whispering gallery mode resonators},
note = { citations $\geq$ 57},
pages = {882--890}
}
@article{zou_quick_2011,
title = {Quick root searching method for resonances of dielectric optical microcavities with the boundary element method},
volume = {19},
url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-19-17-15669},
doi = {10.1364/OE.19.015669},
abstract = {In this paper, we developed an efficient method for searching the resonant eigenfrequency of dielectric optical microcavities by the boundary element method. By transforming the boundary integral equation to a general eigenvalue problem for arbitrary, symmetric, and multi-domain shaped optical microcavities, we analyzed the regular motion of the eigenvalues against the frequency. The new strategy can predict multiple resonances, increase the speed of convergence, and avoid non-physical spurious solutions. These advantages greatly reduce the computation time in the search process of the resonances. Moreover, this method is not only valuable for dielectric microcavities, but is also suitable for other photonic systems with dissipations, whose resonant eigenfrequencies are complex numbers.},
number = {17},
journal = {Optics Express},
author = {Zou, Chang-Ling and Schwefel, Harald G. L. and Sun, Fang-Wen and Han, Zheng-Fu and Guo, Guang-Can},
year = {2011},
keywords = {Mathematical methods in physics, microcavities, Resonators},
note = { citations $\geq$ 29},
pages = {15669--15678}
}
@article{sedlmeir_experimental_2013,
title = {Experimental characterization of an uniaxial angle cut whispering gallery mode resonator},
volume = {21},
url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-21-20-23942},
doi = {10.1364/OE.21.023942},
abstract = {The usual configuration of uniaxial whispering gallery mode resonators is a disk shaped geometry where the optic axis points along the symmetry axis, a so called z-cut resonator. Recently x-cut resonators, where the optic axis lies in the equatorial plane, became of interest as they enable extremely broadband second harmonic generation. In this paper we report on the properties of a more generalized system, the so called angle-cut resonator, where the optic axis exhibits an arbitrary angle against the symmetry axis. We show experimentally that the modal structure and quality factors are similar to common resonators but that the polarization properties differ quite significantly: due to the asymmetry the polarization depends on the equatorial position and is, in general, elliptical.},
number = {20},
urldate = {2013-09-30},
note = { citations $\geq$ 37},
journal = {Optics Express},
author = {Sedlmeir, Florian and Hauer, Martin and F\"urst, Josef U. and Leuchs, Gerd and Schwefel, Harald G. L.},
month = oct,
year = {2013},
keywords = {Birefringence, Crystal optics, Optical resonators, Resonators},
pages = {23942--23949}
}
@article{collodo_sub-khz_2014,
title = {Sub-{kHz} lasing of a CaF$_2$ whispering gallery mode resonator stabilized fiber ring laser},
volume = {22},
url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-22-16-19277},
doi = {10.1364/OE.22.019277},
abstract = {We utilize a high quality calcium fluoride whispering-gallery-mode resonator to passively stabilize a simple erbium doped fiber ring laser with an emission frequency of 196THz (wavelength 1530nm) to an instantaneous linewidth below 650Hz. This corresponds to a relative stability of 3.3 × 10−12 over 16μs. In order to characterize the linewidth we use two identical self-built lasers and a commercial laser to determine the individual lasing linewidth via the three-cornered-hat method. We further show that the lasers are finely tunable throughout the erbium gain region.},
pages = {19277-19283},
number = {16},
journaltitle = {Optics Express},
shortjournal = {Opt. Express},
author = {Collodo, Michele C. and Sedlmeir, Florian and Sprenger, Benjamin and Svitlov, Sergiy and Wang, L. J. and Schwefel, Harald G. L.},
urldate = {2014-08-02},
date = {2014-08-11},
year = {2014},
note = { citations $\geq$ 51},
keywords = {Fiber optics, infrared, Fibers, erbium, Laser resonators, Lasers, ring, Laser stabilization, Wavelength filtering devices}
}
@ARTICLE{SchwefelST05,
author = {Schwefel, Harald G. L. and Stone, A. Douglas and Türeci, Hakan E.},
title = {Polarization properties and dispersion relations for
spiral resonances of a dielectric rod},
journal = {Journal of the Optical Society of America B},
year = {2005},
volume = {22},
pages = {2295-2307},
url= {http://www.opticsinfobase.org/abstract.cfm?URI=josab-22-11-2295 },
doi = {10.1364/JOSAB.22.002295},
note = { citations $\geq$ 16},
abstract = {Dielectric microcavities based on cylindrical and
deformed cylindrical shapes have been employed as resonators for
microlasers. Such systems support spiral resonances with finite
momentum along the cylinder axis. For such modes the boundary
conditions do not separate, and simple TM and TE polarization
states do not exist. We formulate a theory for the dispersion
relations and polarization properties of such resonances for an
infinite dielectric rod of arbitrary cross section and then solve
for these quantities for the case of a circular cross section
(cylinder). Useful analytic formulas are obtained using the eikonal
(Einstein-Brillouin-Keller) method, which are shown to be excellent
approximations to the exact results from the wave equation. The
major finding is that the polarization of the radiation emitted
into the far field is linear up to a polarization critical angle
(PCA) at which it changes to elliptical. The PCA always lies
between the Brewster's and total-internal-reflection angles for the
dielectric, as is shown by an analysis based on the Jones matrices
of the spiraling rays. (c) 2005 Optical Society of America.
}
}
@article{preu_directional_2013,
title = {Directional emission of dielectric disks with a finite scatterer in the {THz} regime},
volume = {21},
url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-21-14-16370},
doi = {10.1364/OE.21.016370},
abstract = {In the Terahertz ({THz)} domain, we investigate both numerically and experimentally the directional emission of whispering gallery mode resonators that are perturbed by a small scatterer in the vicinity of the resonators rim. We determine quality factor degradation, the modal structure and the emission direction for various geometries. We find that scatterers do allow for directional emission without destroying the resonator’s quality factor. This finding allows for new geometries and outcoupling scenarios for active whispering gallery mode structures such as quantum cascade lasers and passive resonators such as evanescent sensors. The experimental results agree well with finite difference time domain simulations.},
number = {14},
urldate = {2013-07-03},
note = { citations $\geq$ 26},
journal = {Optics Express},
author = {Preu, Sascha and Schmid, Sandra I. and Sedlmeir, Florian and Evers, Jörg and Schwefel, Harald G. L.},
month = jul,
year = {2013},
keywords = {microcavities, Resonators, Spectroscopy, teraherz},
pages = {16370--16380},
file = {Opt. Express Snapshot:/Volumes/Macintosh HD/Users/harry/Library/Application Support/Firefox/Profiles/vn6sgh2i.default/zotero/storage/5V5F3N7K/abstract.html:text/html;Preu et al. - 2013 - Directional emission of dielectric disks with a fi.pdf:/Volumes/Macintosh HD/Users/harry/Library/Application Support/Firefox/Profiles/vn6sgh2i.default/zotero/storage/ZBAJ4QVT/Preu et al. - 2013 - Directional emission of dielectric disks with a fi.pdf:application/pdf}
}
@article{schwefel_improved_2009,
title = {An improved method for calculating resonances of multiple dielectric disks arbitrarily positioned in the plane},
volume = {17},
url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-17-15-13178},
doi = {10.1364/OE.17.013178},
abstract = {We present a numerically improved multipole formulation for the calculation of resonances of multiple disks located at arbitrary positions in a 2-d plane, and suitable for the accurate computation of the resonances of large numbers of disks and of high-wavenumber eigenstates. Using a simple reformulation of the field expansions and boundary conditions, we are able to transform the multipole formalism into a linear eigenvalue problem, for which fast and accurate methods are available. Observing that the motion of the eigenvalues in the complex plane is analytic with respect to a two parameter family, we present a numerical algorithm to compute a range of multiple-disk resonances and field distributions using only two diagonalizations. This method can be applied to photonic molecules, photonic crystals, photonic crystal fibers, and random lasers.},
number = {15},
journal = {Optics Express},
author = {Schwefel, Harald G. L. and Poulton, Christopher G.},
month = jul,
year = {2009},
keywords = {coupled resonators, Mathematical methods in physics, microcavities, Resonators},
note = { citations $\geq$ 9},
pages = {13178--13186},
file = {Opt. Express Snapshot:/Volumes/Macintosh HD/Users/harry/Library/Application Support/Firefox/Profiles/vn6sgh2i.default/zotero/storage/MRTQ6M2M/abstract.html:text/html;OSA Journals PDF:/Volumes/Macintosh HD/Users/harry/Library/Application Support/Firefox/Profiles/vn6sgh2i.default/zotero/storage/TGPAI34Z/Schwefel and Poulton - 2009 - An improved method for calculating resonances of m.pdf:application/pdf}
}
@article{schunk_frequency_2016,
title = {Frequency tuning of single photons from a whispering-gallery mode resonator to {MHz}-wide transitions},
issn = {0950-0340},
url = {http://dx.doi.org/10.1080/09500340.2016.1148211},
doi = {10.1080/09500340.2016.1148211},
abstract = {Quantum repeaters rely on interfacing flying qubits with quantum memories. The most common implementations include a narrowband single photon matched in bandwidth and central frequency to an atomic system. Previously, we demonstrated the compatibility of our versatile source of heralded single photons, which is based on parametric down-conversion in a triply resonant whispering-gallery mode resonator, with alkaline transitions [Schunk et al., Optica 2015, 2, 773]. In this paper, we analyse our source in terms of phase matching, available wavelength-tuning mechanisms and applications to narrowband atomic systems. We resonantly address the D1 transitions of caesium and rubidium with this optical parametric oscillator pumped above its oscillation threshold. Below threshold, the efficient coupling of single photons to atomic transitions heralded by single telecom-band photons is demonstrated. Finally, we present an accurate analytical description of our observations. Providing the demonstrated flexibility in connecting various atomic transitions with telecom wavelengths, we show a promising approach to realize an essential building block for quantum repeaters.},
urldate = {2016-03-03},
journal = {Journal of Modern Optics},
author = {Schunk, Gerhard and Vogl, Ulrich and Sedlmeir, Florian and Strekalov, Dmitry V. and Otterpohl, Alexander and Averchenko, V. and Schwefel, Harald G. L. and Leuchs, Gerd and Marquardt, Christoph},
month = mar,
year = {2016},
note = { citations $\geq$ 19},
pages = {1--16}
}
@article{fortsch_near-infrared_2015,
title = {Near-infrared single-photon spectroscopy of a whispering gallery mode resonator using energy-resolving transition edge sensors},
volume = {17},
issn = {2040-8986},
url = {http://iopscience.iop.org/2040-8986/17/6/065501},
doi = {10.1088/2040-8978/17/6/065501},
abstract = {We demonstrate a method to perform spectroscopy of near-infrared single photons without the need of dispersive elements. This method is based on a photon energy resolving transition edge sensor and is applied for the characterization of widely wavelength tunable narrow-band single photons emitted from a crystalline whispering gallery mode resonator. We measure the emission wavelength of tnerated signal and idler photons with an uncertainty of up to 2 nm.},
eprint = {http://arxiv.org/abs/1410.6304},
number = {6},
urldate = {2015-08-25},
journal = {Journal of Optics},
author = {Förtsch, Michael and Gerrits, Thomas and Stevens, Martin J. and Strekalov, Dmitry and Schunk, Gerhard and Fürst, Josef U. and Vogl, Ulrich and Sedlmeir, Florian and Schwefel, Harald G. L. and Leuchs, Gerd and Nam, Sae Woo and Marquardt, Christoph},
month = jun,
year = {2015},
pages = {065501},
note = { citations $\geq$ 20}
}
@article{tureci_efficient_2007,
title = {An efficient Fredholm method for the calculation of highly excited states of billiards},
volume = {40},
location = {harry2007},
abstract = {A numerically efficient Fredholm formulation of the billiard problem is presented. The standard solution in the framework of the boundary integral method in terms of a search for roots of a secular determinant is reviewed first. We next reformulate the singularity condition in terms of a flow in the space of an auxiliary one-parameter family of eigenproblems and argue that the eigenvalues and eigenfunctions are analytic functions within a certain domain. Based on this analytic behavior, we present a numerical algorithm to compute a range of billiard eigenvalues and associated eigenvectors by only two diagonalizations.},
journal = {Journal of Physics A},
author = {Türeci, Hakan E. and Schwefel, Harald G. L.},
year = {2007},
month = oct,
note = { citations $\geq$ 10},
pages = {13869--13882},
doi={10.1088/1751-8113/40/46/004},
note = {Figures used as advertising for the publisher.}
}
%------
@article{kozlov_narrow-bandwidth_2012,
title = {Narrow-bandwidth high-order harmonics driven by long-duration hot spots},
volume = {14},
issn = {1367-2630},
url = {http://iopscience.iop.org/1367-2630/14/6/063036},
doi = {10.1088/1367-2630/14/6/063036},
abstract = {We predict and investigate the emission of high-order harmonics by atoms that cross intense laser hot spots that last for a nanosecond or longer. An atom that moves through a nanometer-scale hot spot at characteristic thermal velocity can emit high-order harmonics in a similar fashion to an atom that is irradiated by a short-duration (picosecond-scale) laser pulse. We analyze the collective emission from a thermal gas and from a jet of atoms. In both cases, the line shape of a high-order harmonic exhibits a narrow spike with spectral width that is determined by the bandwidth of the driving laser. Finally, we discuss a scheme for producing long-duration laser hot spots with intensity in the range of the intensity threshold for high-harmonic generation. In the proposed scheme, the hot spot is produced by a long laser pulse that is consecutively coupled to a high-quality micro-resonator and a metallic nano-antenna. This system may be used for generating ultra-narrow bandwidth extreme-ultraviolet radiation through frequency up-conversion of a low-cost compact pump laser.},
number = {6},
journal = {New Journal of Physics},
author = {Kozlov, Maxim and Kfir, Ofer and Fleischer, Avner and Kaplan, Alex and Carmon, Tal and Schwefel, Harald G. L. and Bartal, Guy and Cohen, Oren},
month = jun,
year = {2012},
note = { citations $\geq$ 6},
pages = {063036},
file = {IOP Full Text PDF:/Volumes/Macintosh HD/Users/harry/Library/Application Support/Firefox/Profiles/vn6sgh2i.default/zotero/storage/SI32QTBB/Kozlov et al. - 2012 - Narrow-bandwidth high-order harmonics driven by lo.pdf:application/pdf}
}
@article{zeltner_crystalline_2014,
title = {Crystalline MgF$_2$ whispering gallery mode resonators for enhanced bulk index sensitivity},
volume = {223},
issn = {1951-6355, 1951-6401},
url = {http://link.springer.com/article/10.1140/epjst/e2014-02241-8},
doi = {10.1140/epjst/e2014-02241-8},
abstract = {We report on experiments on refractrometric sensing with crystalline Whispering Gallery Mode ({WGM}) resonators made of magnesium fluoride, which has a refractive index that is only slightly larger than that of water (Δn ≈ 0.05). The resulting evanescent field of a {WGM} resonator placed in an aqueous environment penetrates therefore deep into the surrounding medium, which makes it a promising candidate for sensing applications. We measured a bulk index sensitivity of 1.09 nm/{RIU} (refractive index unit) in a resonator with a radius of R = 2.91 mm and intrinsic Q-factors of more than 108 in aqueous environments. Furthermore, we describe the fabrication process of crystalline {WGM} resonators.},
number = {10},
urldate = {2014-09-29},
journal = {The European Physical Journal Special Topics},
author = {Zeltner, Richard and Sedlmeir, Florian and Leuchs, Gerd and Schwefel, Harald G. L.},
month = sep,
year = {2014},
note = {citations $\geq$ 11},
keywords = {Atomic, Molecular, Optical and Plasma Physics, Classical Continuum Physics, Condensed Matter Physics, Materials Science, general, Measurement Science and Instrumentation, Physics, general},
pages = {1989--1994}
}
@article{vollmer_taking_2014,
title = {Taking detection to the limit with optical microcavities: Recent advances presented at the 560. {WE} Heraeus Seminar},
volume = {223},
shorttitle = {Taking detection to the limit with optical microcavities},
url = {http://link.springer.com/article/10.1140/epjst/e2014-02271-2},
doi = {10.1140/epjst/e2014-02271-2},
abstract = {We provide a review on the applications of whispering gallery mode resonators in sensing, and biosensing in particular. We highlight the most recent developments in this area, which were presented at the 560. {WE} Heraeus Seminar “Taking Detection to the Limit – Biosensing with Optical Microcavities”.},
number = {10},
urldate = {2014-09-29},
journal = {The European Physical Journal Special Topics},
author = {Vollmer, Frank and Schwefel, Harald G. L.},
month = sep,
year = {2014},
keywords = {Atomic, Molecular, Optical and Plasma Physics, Classical Continuum Physics, Condensed Matter Physics, Materials Science, general, Measurement Science and Instrumentation, Physics, general},
pages = {1907--1916},
note = {\bf editorial}
}
@article{schwefel_chaotic_2015,
title = {A chaotic approach clears up imaging},
volume = {348},
issn = {0036-8075, 1095-9203},
url = {http://www.sciencemag.org/content/348/6231/189},
doi = {10.1126/science.aaa7409},
abstract = {Lasers appear to be ideal light sources for a variety of projection and imaging systems because of their spectral brightness and their ability to produce a beam of light that can be tightly collimated to travel long distances. Lasers owe these extraordinary properties to a quality called coherence. Yet, lasers are not widely used in imaging and projection applications, because the coherence of laser light is just too extreme. Spatiotemporal coherence of the imaging source leads to artifacts such as speckle, caused by the uncontrolled scattering of laser light and multipath interference that degrade the image considerably. Redding et al. (1) now report how a semiconductor laser based on a chaotic cavity can offer a “compact” solution to this problem. The availability of such low-cost, on-chip semiconductor lasers and the possibility to electrically modulate them make such lasers attractive light sources for a variety of applications, ranging from compact projectors to optical coherence tomography.},
number = {6231},
urldate = {2015-04-10},
journal = {Science},
author = {Schwefel, Harald G. L. and Türeci, Hakan E.},
month = apr,
note = {\bf invited Perspective in Science},
year = {2015},
pages = {189--190}}
@article{schwefel_optical_2014,
title = {In optical pumping, less can be more},
volume = {346},
url = {http://www.sciencemag.org/content/346/6207/304},
doi = {10.1126/science.1260707},
abstract = {Lasing is based on the process of optical gain. Once this gain provided through external pumping surpasses the loss in a resonator, lasing sets in and a coherent beam of laser light is emitted. Thus, loss is a natural adversary of lasing, at least in common lasers. A striking amendment to this rule is reported on page 328 of this issue by Peng et al. (1), who report an onset of lasing in a pair of coupled resonators when the total loss of the system is increased.},
number = {6207},
urldate = {2014-10-16},
journal = {Science},
author = {Schwefel, Harald G. L.},
note = {\bf invited Perspective in Science},
month = oct,
year = {2014},
pages = {304--305}
}
@article{foreman_dielectric_2016,
title = {Dielectric tuning and coupling of whispering gallery modes using an anisotropic prism},
volume = {33},
copyright = {© 2016 Optical Society of America},
issn = {1520-8540},
url = {http://www.osapublishing.org/abstract.cfm?uri=josab-33-11-2177},
doi = {10.1364/JOSAB.33.002177},
abstract = {Optical whispering gallery mode (WGM) resonators are a powerful and versatile tool in many branches of science. Fine-tuning of the central frequency and linewidth of individual resonances is, however, desirable in a number of applications, including frequency conversion, optical communications, and efficient light–matter coupling. To this end we present a detailed theoretical analysis of dielectric tuning of WGMs supported in axisymmetric resonators. Using the Bethe–Schwinger equation and adopting an angular spectrum field representation, we study the resonance shift and mode broadening of high-Q WGMs when a planar dielectric substrate is brought close to the resonator. Particular focus is given to use of a uniaxial substrate with an arbitrarily aligned optic axis. Competing red and blue resonance shifts (∼30 MHz), deriving from generation of a near-field material polarization and back action from the radiation continuum, respectively, are found. Anomalous resonance shifts can hence be observed depending on the substrate material, whereas mode broadening on the order of ∼50 MHz can also be realized. Furthermore, polarization-selective coupling with extinction ratios of {\textgreater}104 can be achieved when the resonator and substrate are of the same composition and their optic axes are chosen correctly. Double refraction and properties of outcoupled beams are also discussed.},
number = {11},
urldate = {2016-10-05},
journal = {JOSA B},
author = {Foreman, Matthew R. and Sedlmeir, Florian and Schwefel, Harald G. L. and Leuchs, Gerd},
month = nov,
year = {2016},
note = {citations $\geq$ 24},
pages = {2177--2195},
file = {josab-33-11-2177.pdf:/Users/hschwef/zotero/storage/7N6ED2KA/josab-33-11-2177.pdf:application/pdf;Snapshot:/Users/hschwef/zotero/storage/7GEFI2F3/fulltext.html:text/html}
}
@article{santamaria-botello_maximization_2016,
title = {Maximization of the optical intra-cavity power of whispering-gallery mode resonators via coupling prism},
volume = {24},
copyright = {© 2016 Optical Society of America},
issn = {1094-4087},
url = {http://www.osapublishing.org/abstract.cfm?uri=oe-24-23-26503},
doi = {10.1364/OE.24.026503},
abstract = {In this paper, a detailed description of the optical coupling into a Whispering Gallery Mode (WGM) resonator through a prism via frustrated total internal reflection (FTIR) is presented. The problem is modeled as three media with planar interfaces and closed expressions for FTIR are given. Then, the curvature of the resonator is taken into account and the mode overlap is theoretically studied. A new analytical expression giving the optimal geometry of a disc-shaped or ring-shaped resonator for maximizing the intra-cavity circulating power is presented. Such expression takes into consideration the spatial distribution of the WGM at the surface of the resonator, thus being more accurate than the currently used expressions. It also takes into account the geometry of the prism. It is shown an improvement in the geometry values used with the current expressions of about 30\%. The reason why the pump laser signal can be seen in experiments under critical coupling is explained on this basis. Then, the conditions required for exciting the highest possible optical power inside the resonator are obtained. The aim is to achieve a highly-efficient up-conversion of a THz signal into the optical domain via the second-order nonlinearity of the resonator material.},
number = {23},
urldate = {2016-11-29},
journal = {Optics Express},
note = {citations $\geq$ 9},
author = {Santamaría-Botello, Gabriel A. and Muñoz, Luis Enrique García and Sedlmeir, Florian and Preu, Sascha and Segovia-Vargas, D. and Abdalmalak, K. Atia and Romano, S. Llorente and Lampérez, A. García and Malzer, Stefan and Döhler, Gottfried H. and Schwefel, Harald G. L. and Weber, Heiko B.},
month = nov,
year = {2016},
pages = {26503--26514}}
@article{sedlmeir_polarization-selective_2017,
title = {Polarization-{Selective} {Out}-{Coupling} of {Whispering}-{Gallery} {Modes}},
volume = {7},
url = {http://link.aps.org/doi/10.1103/PhysRevApplied.7.024029},
doi = {10.1103/PhysRevApplied.7.024029},
abstract = {Whispering-gallery mode (WGM) resonators are an important platform for linear, nonlinear, and quantum optical experiments. In such experiments, independent control of in-coupling and out-coupling rates to different modes can lead to higher conversion efficiencies and greater flexibility in the generation of nonclassical states based on parametric down-conversion. In this work, we introduce a scheme that enables selective out-coupling of WGMs belonging to a specific polarization family, while the orthogonally polarized modes remain largely unperturbed. Our technique utilizes material birefringence in both the resonator and the coupler such that a negative (positive) birefringence allows for polarization-selective coupling to TE (TM) WGMs. We formulate a refined coupling condition suitable for describing the case where the refractive indices of the resonator and the coupler are almost the same, from which we derive a criterion for polarization-selective coupling. Finally, we experimentally demonstrate our proposed method using a lithium niobate disk resonator coupled to a lithium niobate prism, where we show a 22-dB suppression of coupling to TM modes relative to TE modes.},
number = {2},
urldate = {2017-03-14},
journal = {Physical Review Applied},
author = {Sedlmeir, Florian and Foreman, Matthew R. and Vogl, Ulrich and Zeltner, Richard and Schunk, Gerhard and Strekalov, Dmitry V. and Marquardt, Christoph and Leuchs, Gerd and Schwefel, Harald G. L.},
note = { citations $\geq$ 31},
month = feb,
year = {2017},
pages = {024029}
}
@article{ge_optical_2017,
title = {Optical microcavities: new understandings and developments},
volume = {5},
copyright = {© 2017 Chinese Laser Press},
issn = {2327-9125},
shorttitle = {Optical microcavities},
url = {https://www.osapublishing.org/abstract.cfm?uri=prj-5-6-OM1},
doi = {10.1364/PRJ.5.000OM1},
abstract = {Optical microcavities have attracted tremendous interest in both fundamental and applied research in the past few decades, thanks to their small footprint, easy integrability, and high quality factors. Using total internal reflection from a dielectric interface or a photonic band gap in a periodic system, these photonic structures do not rely on conventional metal-coated mirrors to confine light in small volumes, which have brought forth new developments in both classical and quantum optics. This focus issue showcases several such developments and related findings, which may pave the way for the next generation of on-chip photonic devices based on microcavities.},
number = {6},
urldate = {2017-12-11},
journal = {Photonics Research},
author = {Ge, Li and Feng, Liang and Schwefel, Harald G. L.},
month = dec,
year = {2017},
keywords = {microcavities, Micro-optical devices, Microstructure fabrication},
pages = {OM1--OM3},
note = { editorial, citations $\geq$ 16},
file = {Full Text PDF:/Users/hschwef/zotero/storage/EVX8HZDJ/Ge et al. - 2017 - Optical microcavities new understandings and deve.pdf:application/pdf;Snapshot:/Users/hschwef/zotero/storage/QN9IQSKW/abstract.html:text/html}
}
@article{trainor_selective_2018,
title = {Selective {Coupling} {Enhances} {Harmonic} {Generation} of {Whispering}-{Gallery} {Modes}},
volume = {9},
url = {https://link.aps.org/doi/10.1103/PhysRevApplied.9.024007},
doi = {10.1103/PhysRevApplied.9.024007},
abstract = {We demonstrate second-harmonic generation (SHG) in an x-cut congruent lithium niobate (LN) whispering-gallery mode (WGM) resonator. First, we show theoretically that independent control of the coupling of the pump and signal modes is optimal for high conversion rates. A coupling scheme based on our earlier work [F. Sedlmeir et al., Phys. Rev. Applied 7, 024029 (2017)] is then implemented experimentally to verify this improvement. Thereby, we are able to improve on the efficiency of SHG by more than an order of magnitude by selectively outcoupling using a LN prism, utilizing the birefringence of it and the resonator in kind. This method is also applicable to other nonlinear processes in WGM resonators.},
number = {2},
urldate = {2018-02-13},
journal = {Physical Review Applied},
author = {Trainor, Luke S. and Sedlmeir, Florian and Peuntinger, Christian and Schwefel, Harald G. L.},
month = feb,
year = {2018},
pages = {024007},
note = { citations $\geq$ 19},
file = {APS Snapshot:/Users/hschwef/zotero/storage/ZJ7UHHTW/PhysRevApplied.9.html:text/html;Trainor et al. - 2018 - Selective Coupling Enhances Harmonic Generation of.pdf:/Users/hschwef/zotero/storage/WDQTA7K6/Trainor et al. - 2018 - Selective Coupling Enhances Harmonic Generation of.pdf:application/pdf}
}
@article{kornienko_towards_2018,
title = {Towards terahertz detection and calibration through spontaneous parametric down-conversion in the terahertz idler-frequency range generated by a 795 nm diode laser system},
volume = {3},
url = {https://aip.scitation.org/doi/full/10.1063/1.5011201},
doi = {10.1063/1.5011201},
abstract = {We study a calibration scheme for terahertz wave nonlinear-optical detectors based on spontaneous parametric down-conversion. Contrary to the usual low wavelength pump in the green, we report here on the observation of spontaneous parametric down-conversion originating from an in-growth poled lithium niobate crystal pumped with a continuous wave 50 mW, 795 nm diode laser system, phase-matched to a terahertz frequency idler wave. Such a system is more compact and allows for longer poling periods as well as lower losses in the crystal. Filtering the pump radiation by a rubidium-87 vapor cell allowed the frequency-angular spectra to be obtained down to ∼0.5 THz or ∼1 nm shift from the pump radiation line. The presence of an amplified spontaneous emission “pedestal” in the diode laser radiation spectrum significantly hampers the observation of spontaneous parametric down-conversion spectra, in contrast to conventional narrowband gas lasers. Benefits of switching to longer pump wavelengths are pointed out, such as collinear optical-terahertz phase-matching in bulk crystals.},
number = {5},
urldate = {2018-03-15},
journal = {APL Photonics},
author = {Kornienko, Vladimir V. and Kitaeva, Galiya Kh. and Sedlmeir, Florian and Leuchs, Gerd and Schwefel, Harald G. L.},
month = mar,
year = {2018},
pages = {051704},
note = {citations $\geq$ 21},
file = {Full Text PDF:/Users/hschwef/zotero/storage/KFMRKTI5/Kornienko et al. - 2018 - Towards terahertz detection and calibration throug.pdf:application/pdf;Snapshot:/Users/hschwef/zotero/storage/VNMSCTF4/1.html:text/html}
}
@article{sayson_origins_2018,
title = {Origins of clustered frequency combs in {Kerr} microresonators},
volume = {43},
copyright = {\&\#169; 2018 Optical Society of America},
issn = {1539-4794},
url = {https://www.osapublishing.org/ol/abstract.cfm?uri=ol-43-17-4180},
doi = {10.1364/OL.43.004180},
abstract = {Recent experiments have demonstrated the generation of widely spaced parametric sidebands that can evolve into \&\#x201C;clustered\&\#x201D; optical frequency combs in Kerr microresonators. Here we describe the physics that underpins the formation of such clustered comb states. In particular, we show that the phase matching required for the initial sideband generation is such that (at least) one of the sidebands experiences anomalous dispersion, enabling the sideband to drive frequency comb formation via degenerate and non-degenerate four-wave mixing. We validate our proposal through a combination of experimental observations made in a magnesium-fluoride microresonator and corresponding numerical simulations. We also investigate the coherence properties of the resulting clustered frequency combs. Our findings provide valuable insights on the generation and dynamics of widely spaced parametric sidebands and clustered frequency combs in Kerr microresonators.},
number = {17},
urldate = {2018-08-22},
journal = {Optics Letters},
author = {Sayson, Noel Lito B. and Pham, Hoan and Webb, Karen E. and Ng, Vincent and Trainor, Luke S. and Schwefel, Harald G. L. and Coen, Stéphane and Erkintalo, Miro and Murdoch, Stuart G.},
month = sep,
note = { citations $\geq$ 16},
year = {2018},
keywords = {Frequency combs, Dispersion, Erbium doped fiber amplifiers, Parametric oscillators, Phase matching, Tapered fibers},
pages = {4180--4183},
file = {Sayson et al. - 2018 - Origins of clustered frequency combs in Kerr micro.pdf:/Users/harry/Zotero/storage/VMBU2BPZ/Sayson et al. - 2018 - Origins of clustered frequency combs in Kerr micro.pdf:application/pdf;Snapshot:/Users/harry/Zotero/storage/7NZDIHVF/abstract.html:text/html}
}
@article{botello_sensitivity_2018,
title = {Sensitivity limits of millimeter-wave photonic radiometers based on efficient electro-optic upconverters},
volume = {5},
copyright = {\&\#169; 2018 Optical Society of America},
issn = {2334-2536},
url = {https://www.osapublishing.org/optica/abstract.cfm?uri=optica-5-10-1210},
doi = {10.1364/OPTICA.5.001210},
abstract = {Conventional ultra-high sensitivity detectors in the millimeter-wave range are usually cooled as their own thermal noise at room temperature would mask the weak received radiation. The need for cryogenic systems increases the cost and complexity of the instruments, hindering the development of, among others, airborne and space applications. In this work, the nonlinear parametric upconversion of millimeter-wave radiation to the optical domain inside high-quality (Q) lithium niobate whispering-gallery mode (WGM) resonators is proposed for ultra-low noise detection. We experimentally demonstrate coherent upconversion of millimeter-wave signals to a 1550\&\#x00A0;nm telecom carrier, with a photon conversion efficiency surpassing the state-of-the-art by 2 orders of magnitude. Moreover, a theoretical model shows that the thermal equilibrium of counterpropagating WGMs is broken by overcoupling the millimeter-wave WGM, effectively cooling the upconverted mode and allowing ultra-low noise detection. By theoretically estimating the sensitivity of a correlation radiometer based on the presented scheme, it is found that room-temperature radiometers with better sensitivity than state-of-the-art high-electron-mobility transistor (HEMT)-based radiometers can be designed. This detection paradigm can be used to develop room-temperature instrumentation for radio astronomy, earth observation, planetary missions, and imaging systems.},
number = {10},
urldate = {2018-09-29},
note = { citations $\geq$ 27},
journal = {Optica},
author = {Botello, Gabriel Santamaría and Sedlmeir, Florian and Rueda, Alfredo and Abdalmalak, Kerlos Atia and Brown, Elliott R. and Leuchs, Gerd and Preu, Sascha and Segovia-Vargas, Daniel and Strekalov, Dmitry V. and Muñoz, Luis Enrique García and Schwefel, Harald G. L.},
month = oct,
year = {2018},
keywords = {Sum frequency generation, Q factor, Power spectral density, Amplified spontaneous emission, Coupled mode theory, Nonlinear parametric processes},
pages = {1210--1219},
file = {Full Text PDF:/Users/harry/Zotero/storage/RRRPTPZU/Botello et al. - 2018 - Sensitivity limits of millimeter-wave photonic rad.pdf:application/pdf;Snapshot:/Users/harry/Zotero/storage/FN5EWMLM/abstract.html:text/html}
}
@article{vogt_prism_2018,
title = {Prism coupling of high-{Q} terahertz whispering-gallery-modes over two octaves from 0.2 {THz} to 1.1 {THz}},
volume = {26},
copyright = {\&\#169; 2018 Optical Society of America},
issn = {1094-4087},
url = {https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-24-31190},
doi = {10.1364/OE.26.031190},
abstract = {We report on prism coupling of high-quality (high-Q) terahertz (THz) whispering-gallery modes (WGMs) in spherical high resistivity float zone grown silicon (HRFZ-Si) resonators over two octaves from 0.2 THz to 1.1 THz. The WGMs are excited using a HRFZ-Si prism and show unprecedented quality factors of up to 2.2 \&\#x000D7; 104. A detailed discussion of the phase-and mode-matching criteria of the prism coupling scheme implemented in the continuous wave THz spectroscopy system is presented. The results provide numerous opportunities for passive ultra-broadband high-Q devices operating in the THz frequency range.},
number = {24},
urldate = {2018-12-11},
journal = {Optics Express},
author = {Vogt, Dominik Walter and Jones, Angus Harvey and Schwefel, Harald G. L. and Leonhardt, Rainer},
note = { citations $\geq$ 16},
month = nov,
year = {2018},
keywords = {Mie theory, Total internal reflection, Terahertz spectroscopy, Refractive index, Narrow band filters, Transmission coefficient},
pages = {31190--31198}
}
@article{vogt_anomalous_2019,
title = {Anomalous blue-shift of terahertz whispering-gallery modes via dielectric and metallic tuning},
volume = {44},
copyright = {\&\#169; 2019 Optical Society of America},
issn = {1539-4794},
url = {https://www.osapublishing.org/ol/abstract.cfm?uri=ol-44-6-1319},
doi = {10.1364/OL.44.001319},
abstract = {The vast majority of resonant systems show a red-shift for the resonance frequency when a perturbation, e.g.,\&\#x00A0;losses, is introduced to the system. In contrast, here we report for the first time, to the best of our knowledge, the experimental demonstration of both red- and anomalous blue-shifting of whispering-gallery modes (WGMs) using dielectric and metallic substrates. The maximum blue-shift is more than three times as large as the expected red-shift, proving that the anomalous blue-shift is more than a peculiar curiosity. The experiments are performed in the terahertz frequency range with coherent continuous-wave spectroscopy. The results establish dielectric and metallic tuning as a novel and viable approach to tune high-quality WGMs and provide valuable insights into the anomalous blue-shift of WGM cavity systems. The tuning capabilities for these compact monolithic resonators are of significant interest for fundamental science and technological applications alike.},
number = {6},
urldate = {2019-03-14},
note = { citations $\geq$ 9},
journal = {Optics Letters},
author = {Vogt, Dominik Walter and Jones, Angus Harvey and Schwefel, Harald G. L. and Leonhardt, Rainer},
month = mar,
year = {2019},
keywords = {Whispering gallery modes, Resonance, Refractive index, Phase shift, Effective refractive index, Light matter interactions},
pages = {1319--1322}
}
@article{rueda_resonant_2019,
title = {Resonant electro-optic frequency comb},
volume = {568},
copyright = {2019 The Author(s), under exclusive licence to Springer Nature Limited},
issn = {1476-4687},
url = {https://www.nature.com/articles/s41586-019-1110-x},
doi = {10.1038/s41586-019-1110-x},
abstract = {A low-power, fixed microwave signal in combination with an optical-pump signal generates an optical frequency comb that spans the whole wavelength range of the telecommunications C-band, with possible applications ranging from spectroscopy to optical communications.},
number = {7752},
urldate = {2019-04-17},
note = { citations $\geq$ 103, featured in popular press},
journal = {Nature},
author = {Rueda, Alfredo and Sedlmeir, Florian and Kumari, Madhuri and Leuchs, Gerd and Schwefel, Harald G. L.},
month = apr,
year = {2019},
pages = {378}
}
@article{sayson_octave-spanning_2019,
title = {Octave-spanning tunable parametric oscillation in crystalline {Kerr} microresonators},
copyright = {2019 The Author(s), under exclusive licence to Springer Nature Limited},
issn = {1749-4893},
url = {https://www.nature.com/articles/s41566-019-0485-4},
doi = {10.1038/s41566-019-0485-4},
abstract = {Through degenerate Kerr four-wave mixing in ultrahigh-Q crystalline microresonators made of magnesium fluoride, tunable conversion of a compact, low-power telecommunications laser over an entire optical octave from 1,083nm to 2,670nm, with signatures of mid-infrared sidebands at almost 4,000nm, is shown.},
urldate = {2019-07-08},
note = { citations $\geq$ 62},
journal = {Nature Photonics},
author = {Sayson, Noel Lito B. and Bi, Toby and Ng, Vincent and Pham, Hoan and Trainor, Luke S. and Schwefel, Harald G. L. and Coen, Stéphane and Erkintalo, Miro and Murdoch, Stuart G.},
month = jul,
year = {2019},
pages = {1}
}
@article{otterpohl_squeezed_2019,
title = {Squeezed vacuum states from a whispering gallery mode resonator},
volume = {6},
copyright = {\&\#169; 2019 Optical Society of America},
issn = {2334-2536},
url = {https://www.osapublishing.org/optica/abstract.cfm?uri=optica-6-11-1375},
doi = {10.1364/OPTICA.6.001375},
abstract = {Squeezed vacuum states enable optical measurements below the quantum limit and hence are a valuable resource for applications in quantum metrology and also quantum communication. However, most available sources require high pump powers in the milliwatt range and large setups that hinder real-world applications. Furthermore, degenerate operation of such systems presents a challenge. Here, we use a compact crystalline whispering gallery mode resonator made of lithium niobate as a degenerate parametric oscillator. We demonstrate about 1.4\&\#x00A0;dB noise reduction below the shot-noise level for only 300\&\#x00A0;\&\#x03BC;W of pump power in degenerate single-mode operation. Furthermore, we report a record pump threshold as low as 1.35\&\#x00A0;\&\#x03BC;W. Our results show that the whispering gallery-based approach presents a promising platform for a compact and efficient source for nonclassical light.},
number = {11},
urldate = {2019-10-23},
note = { citations $\geq$ 30},
journal = {Optica},
author = {Otterpohl, Alexander and Sedlmeir, Florian and Vogl, Ulrich and Dirmeier, Thomas and Shafiee, Golnoush and Schunk, Gerhard and Strekalov, Dmitry V. and Schwefel, Harald G. L. and Gehring, Tobias and Andersen, Ulrik L. and Leuchs, Gerd and Marquardt, Christoph},
month = nov,
year = {2019},
keywords = {Whispering gallery modes, Quantum communications, Squeezed states, Parametric down conversion, Single point diamond turning, Beam splitters},
pages = {1375--1380},
file = {Otterpohl et al. - 2019 - Squeezed vacuum states from a whispering gallery m.pdf:/Users/harry/Zotero/storage/5NL7JKBR/Otterpohl et al. - 2019 - Squeezed vacuum states from a whispering gallery m.pdf:application/pdf;Snapshot:/Users/harry/Zotero/storage/LACW2VNV/abstract.html:text/html}
}
@article{lambert_coherent_2020,
title = {Coherent {Conversion} {Between} {Microwave} and {Optical} {Photons}—{An} {Overview} of {Physical} {Implementations}},
volume = {3},
copyright = {© 2019 The Authors. Published by WILEY‐VCH Verlag GmbH \& Co. KGaA, Weinheim},
issn = {2511-9044},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/qute.201900077},
doi = {10.1002/qute.201900077},
abstract = {Quantum information technology based on solid state qubits has created much interest in converting quantum states from the microwave to the optical domain. Optical photons, unlike microwave photons, can be transmitted by fiber, making them suitable for long distance quantum communication. Moreover, the optical domain offers access to a large set of very well-developed quantum optical tools, such as highly efficient single-photon detectors and long-lived quantum memories. For a high fidelity microwave to optical transducer, efficient conversion at single photon level and low added noise is needed. Currently, the most promising approaches to build such systems are based on second-order nonlinear phenomena such as optomechanical and electro-optic interactions. Alternative approaches, although not yet as efficient, include magneto-optical coupling and schemes based on isolated quantum systems like atoms, ions, or quantum dots. Herein, the necessary theoretical foundations for the most important microwave-to-optical conversion experiments are provided, their implementations are described, and the current limitations and future prospects are discussed.},
number = {1},
urldate = {2020-03-09},
journal = {Advanced Quantum Technologies},
author = {Lambert, Nicholas J. and Rueda, Alfredo and Sedlmeir, Florian and Schwefel, Harald G. L.},
year = {2020},
keywords = {quantum optics, nonlinear optics, microwave to optical transduction, quantum communication},
pages = {1900077},
note = {citations $\geq$ 122, Cover Article}
}
@article{lambert_random_2020,
title = {Random telegraph signal analysis with a recurrent neural network},
volume = {102},
url = {https://link.aps.org/doi/10.1103/PhysRevE.102.012312},
doi = {10.1103/PhysRevE.102.012312},
abstract = {We use an artificial neural network to analyze asymmetric noisy random telegraph signals, and extract underlying transition rates. We demonstrate that a long short-term memory neural network can outperform other methods, particularly for noisy signals and measurements with limited bandwidths. Our technique gives reliable results as the signal-to-noise ratio approaches one, and over a wide range of underlying transition rates. We apply our method to random telegraph signals generated by quasiparticle poisoning in a superconducting double dot, allowing us to extend our measurement of quasiparticle dynamics to new temperature regimes.},
number = {1},
urldate = {2020-07-21},
journal = {Physical Review E},
author = {Lambert, Nicholas J. and Esmail, A. A. and Edwards, M. and Ferguson, A. J. and Schwefel, H. G. L.},
month = jul,
year = {2020},
note = { citations $\geq$ 3},
pages = {012312},
file = {APS Snapshot:/Users/harry/Zotero/storage/VI63NKED/PhysRevE.102.html:text/html;Full Text PDF:/Users/harry/Zotero/storage/BKZ8CFWF/Lambert et al. - 2020 - Random telegraph signal analysis with a recurrent .pdf:application/pdf}
}
@article{hendry_experimental_2020,
title = {Experimental observation of internally pumped parametric oscillation and quadratic comb generation in a $\chi^{(2)}$ whispering-gallery-mode microresonator},
volume = {45},
copyright = {\&\#169; 2020 Optical Society of America},
issn = {1539-4794},
url = {https://www.osapublishing.org/ol/abstract.cfm?uri=ol-45-5-1204},
doi = {10.1364/OL.385751},
abstract = {We report on the experimental observation of internally pumped parametric oscillation in a high-\${\textbackslash}!Q\$Q lithium niobate microresonator under conditions of natural phase matching. Specifically, launching near-infrared pump light around 1060 nm into a \$ z \$z-cut congruent lithium niobate microresonator, we observe the generation of optical sidebands around the input pump under conditions where second-harmonic generation is close to natural phase matching. We find that a wide range of different sideband frequency shifts can be generated by varying the experimental parameters. Under particular conditions, we observe the cascaded generation of several sidebands around the pump—the first steps of optical frequency comb generation via cavity-enhanced second-harmonic generation.},
number = {5},
urldate = {2020-02-25},
note = { citations $\geq$ 32},
journal = {Optics Letters},
author = {Hendry, Ian and Trainor, Luke S. and Xu, Yiqing and Coen, Stéphane and Murdoch, Stuart G. and Schwefel, Harald G. L. and Erkintalo, Miro},
month = mar,
year = {2020},
keywords = {Nonlinear optical devices, Amplified spontaneous emission, Single point diamond turning, Nonlinear effects, Tunable diode lasers, Stimulated Brillouin scattering},
pages = {1204--1207},
file = {Snapshot:/Users/harry/Zotero/storage/KGJTYITA/abstract.html:text/html}
}
@article{shafiee_nonlinear_2020,
title = {Nonlinear power dependence of the spectral properties of an optical parametric oscillator below threshold in the quantum regime},
volume = {22},
issn = {1367-2630},
url = {https://doi.org/10.1088/1367-2630/ab9a87},
doi = {10.1088/1367-2630/ab9a87},
abstract = {Photon pairs and heralded single photons, obtained from cavity-assisted parametric down conversion (PDC), play an important role in quantum communications and technology. This motivated a thorough study of the spectral and temporal properties of parametric light, both above the optical parametric oscillator (OPO) threshold, where the semiclassical approach is justified, and deeply below it, where the linear cavity approximation is applicable. The pursuit of a higher two-photon emission rate leads into an interesting intermediate regime, between above OPO threshold and very low pump power, where the OPO still operates considerably below the threshold but the nonlinear cavity phenomena cannot be neglected anymore. Here, we investigate this intermediate regime and show that the spectral and temporal properties of the photon pairs, as well as their emission rate, may significantly differ from the widely accepted linear model. The observed phenomena include frequency pulling and broadening in the temporal correlation for the down-converted optical fields. These factors need to be taken into account when devising practical applications of the high-rate cavity-assisted spontaneous PDC sources.},
number = {7},
urldate = {2020-12-17},
journal = {New Journal of Physics},