and single nanoparticle detection with whyspering gallery Raman microlasers"
SK Ozdemir, J Zhu, X Yang, B Peng, H Yilmaz, L He, F Monifi, GL Long, L Yang
arXiv preprint arXiv:1401.2033
"Parity-time-symmetric whispering-gallery microcavities"
B Peng, SK Ozdemir, F Lei, F Monifi, M Gianfreda, GL Long, S Fan, F Nori, CM Bender, L Yang
Nature Physics (in press) [arXiv preprint arXiv:1308.4564]
I. Kandas, B. Zhang, C. Daengngam, I. Ashry, C.-Y. Jao, B. Peng, S. K. Ozdemir, H. D. Robinson, J. R. Heflin, L. Yang, and Y. Xu,
Optics Express, Vol. 21, Issue 18, pp. 20601-20610
"Tunable add-drop filter using an active whispering gallery mode microcavity"
F Monifi, SK Ozdemir, L Yang
App. Phy. Lett. 103, 181103
J. Zhang, Y. Liu, S. K. Ozdemir, R. Wu, F. Gao, X. Wang, L. Yang and F. Nori, Scientific Reports. 3, 2211
"Encapsulation of a Fiber Taper Coupled Microtoroid Resonator in a Polymer Matrix"
F. Monifi, S. K. Ozdemir, J. Friedlein, L. Yang
Photonics Technology Letters, IEEE 25 (15), 1458-1461
"Statistics of multiple-scatterer-induced frequency splitting in whispering gallery microresonators and microlasers"
L. He, S. K Özdemir, J. Zhu, F. Monifi, H. Yılmaz and L. Yang
New Journal of Physics 15 (7)
"On-chip whispering-gallery-mode microlasers and their applications for nanoparticle sensing"
S. K. Ozdemir, L He, J Zhu, F Monifi, W Kim, O Kenechukwu, H Yilmaz, SH Huang, L Yang
SPIE OPTO, 86270N-86270N-10
L. He, S. K. Ozedemir, and L. Yang,
Lasers & Photonics Reviews, Vol. 7, No. 1, 60-82 (2013) Invited
F. Vollmer and L. Yang,
Nanophotonics, Vol. 1, 267-291 (2012) Invited
"Detection and size measurement of individual hemozoin nanocrystals in aquatic environment using a whispering gallery mode resonator"
W Kim, SK Ozdemir, J Zhu, F Monifi, C Coban, L Yang
Optics Express 20 (28), 29426-29446
B. Peng, S. K. Ozdemir, J. Zhu and L. Yang,
Optics Letters, Vol. 37, Issue 16, pp. 3435-3437 (2012)
"A Robust and Tunable Add-Drop Filter Using Whispering Gallery Mode Microtoroid Resonator"
F Monifi, J Friedlein, S Ozdemir, L Yang
IEEE Journal of Lightwave Technology, Vol. PP, Issue 99 (2012)
J. Zhu, S.K. Ozdemir and L. Yang,
Nature Photonics, (2011). Cover image for the Nov 11 issue of Nature Photonics, Vol. 5, 653-654
"Optothermal spectroscopy of whispering gallery microresonators"
J. Zhu, Ş. K. Özdemir, L. He, and L. Yang,
Applied Physics Letters, 99, 171101 (2011),
"Single virus and nanoparticle size spectrometry by whispering-gallery-mode microcavities "
J. Zhu, S.K. Ozdemir, L. He, D. R. Chen and L. Yang,
Optics Express, Vol. 19, Issue 17, pp 16195-16206 (2011)
Selected for publication in the Virtual Journal for Biomedical Optics (VJBO)Vol. 6, Issue 9.
"Detecting single viruses and nanoparticles using whispering gallery microlasers"
L. He, S.K. Ozdemir, J. Zhu, Woosung Kim, and L. Yang,
Nature Nanotechnology, doi:10.1038/nnano.2011.99, June 26 (2011)
"Optical detection of single nanoparticles with a subwavelength fiber-taper"
J. Zhu, S.K. Ozdemir, and L. Yang,
Photonics Technology Letters,
Vol. 23, Issue 18, pp 1346-1348 (2011)
"Observation and characterization of mode splitting in microsphere resonators in aquatic environment"
Woosung Kim, Sahin K. Ozdemir, Jiangang Zhu, and L. Yang,
Applied Physics Letters, Vol. 98, 141106 (2011)
"Estimation of Purcell factor from mode-splitting spectra in an optical microcavity"
S.K. Ozdemir, J. Zhu , L. He and L. Yang,
Phy. Rev. A, Vol. 83, 033817 (2011)
"Demonstration of mode splitting in an optical microcavity in aqueous environment "
Woosung Kim, Sahin K. Ozdemir, Jiangang Zhu ,L. He and L. Yang,
Applied Physics Letters, Vol. 97, 071111 (2010)
"Controlled manipulation of mode splitting in an optical microcavity by two Rayleigh scatterers"
J. Zhu , S.K. Ozdemir, L. He and L. Yang,
Opt. Express, Vol. 18, Issue, 23, 23535-23543 (2010)
"Ultrasensitive detection of mode splitting in active optical microcavities"
L. He, S.K. Ozdemir, J. Zhu and L. Yang,
Phy. Rev. A, Vol. 82, Issue 5, 053810 (2010)
"Gain-induced Evolution of Mode Splitting Spectra in a High-Q Active Microresonator "
L. He, S.K. Ozdemir, J. Zhu and L. Yang,
IEEE Journal of Quantum Electronics, Vol. 46, 1626-1633 (2010)
"Scatterer induced mode splitting in PDMS coated microresonators "
L. He, S.K. Ozdemir, J. Zhu and L. Yang,
App. Phy. Lett. Vol. 96, 221101 (2010)
"Self-pulsation in fiber-coupled on-chip microcavity lasers"
L. He, S.K. Ozdemir, J. Zhu and L. Yang,
Opt. Letters, Vol.35, 256-258 (2010)
"On-chip single nanoparticle detection and sizing by mode splitting in an ultrahigh-Q microresonator"
J. Zhu, S.K. Ozdemir, Y.F.Xiao, L. Li, L. He, D.R. Chen and L. Yang,
Nature Photonics, doi:10.1038/nphoton.2009.237, Dec. 13 (2009)
"Oscillatory thermal dynamics in high-Q PDMS-coated silica toroidal microresonators"
L. He, Y.F.Xiao, J. Zhu, S.K. Ozdemir and L. Yang,
Opt. Exp. Vol. 17, 9571-9581 (2009)
"Electromagnetically induced transparency-like effect in a single polydimethylsiloxane-coated silica microtoroid"
Y.F. Xiao, L. He and L. Yang,
App. Phy. Lett. Vol. 94, 231115 (2009)
"Fabrication of high-Q PDMS optical microspheres with applications towards thermal sensing"
C.H. Dong, L. He, Y.F.Xiao, V. Goddam, S.K. Ozdemir, Z.F. Han, G.C. Guo and L. Yang,
App. Phy. Lett. Vol. 94, 231119 (2009)
"High-Q Plasmon-polariton whispering-gallery microcavity"
B. Min, E. Ostby, V. Sorger, E. Ulin-Avila, L. Yang, X. Zhang, and K. J. Vahala,
Nature, Vol. 457, 455-458 (2009)
"A green light silica microlaser by three-photon upcoversion"
T. Lu, L. Yang, R.V.A. Van Loon, A. Polman and K. Vahala,
Opt. Lett. Vol. 34, 482-484 (2009)
"Low-threshold microlaser in a high-Q asymmetrical microcavity"
Y.F.Xiao, C.H. Dong, C.L. Zou, Z.F. Han, L. Yang and G.C. Guo,
Opt. Lett. Vol. 34, 509-511 (2009)
"Compensation of thermal refraction effect in high-Q toroidal microresonator by polydimethylsiloxane coating"
L. He, Y.F.Xiao, C.Dong, J. Zhu, V. Goddam, and L. Yang, App. Phy. Lett. Vol. 93, 201102 (2008)
We experimentally and theoretically characterize the thermal refraction effect in a silica microtoroid and demonstrate that such effect can be reduced or even eliminated by applying a thin layer of polydimethylsiloxane (PDMS) to the surface of the silica resonator. By increasing the coating thickness, the whispering gallery modes (WGMs) experience a transition from redshift to blueshift induced by thermal absorption. Experiment results demonstrate that at the thickness of 0.52 um, the fundamental WGM with observed Q factor of 1.5x10^6 shows no shift with the input optical power since the thermal refraction of the silica for this mode is compensated completely by the PDMS layer, which has an opposite thermal refraction effect. This work shows that the PDMS layer could be used to reduce thermal noise in high-Q silica microcavities for applications in sensing, lasing and nonlinear optics.
This paper has been selected for the December 1, 2008 issue of Virtual Journal of Nanoscale Science & Technology.
"Quantum nondemolition measurement of photon number via optical Kerr effect in an ultra-high-Q microtoroid cavity"
Y.F.Xiao, S.K. Ozdemir, V. Goddam, C.H.Dong, N. Imoto and L. Yang, Opt. Expressï¼Œ Vol. 16, 21462-21475, 2008
We theoretically investigate a quantum nondemolition (QND) measurement with optical Kerr effect in an ultra-high-Q microtoroidal System. The analytical and numerical results predict that the present QND measurement scheme possesses a high sensitivity, which allows for detecting few photons or even single photons. Ultra-high-Q toroidal microcavity may provide a novel experimental platform to study quantum physics with nonlinear optics at low light levels.
"Coupled Optical microcavities: an enhanced refractometric sensing configuration"
Yun-Feng Xiao, Venkat Gaddam and Lan Yang, Opt. Express, 16, 12538-12543 (2008)
We theoretically investigate the application of coupled optical microcavities as refractive index sensors. Coupled microcavities support a very sharp asymmetrical Fano resonance, which gives rise to faster changes in output transmission than the changes from a single cavity. With the output transmission at a fixed wavelength that varies much faster than it does in a single-cavity resonance, the result is enhanced sensitivity of the device to the changes in refractive index. In addition, it is observed that both thermal and optical Kerr effects can be utilized to improve the sensitivity.
"Coupling whispering-gallery-mode microcavities with modal coupling mechanism"
Yun-Feng Xiao, Bumki Min, Xiaoshun Jiang, Chun-Hua Dong, and Lan Yang
IEEE J. of Quantum Electronics, Vol. 44, 1065 (2008)
We theoretically describe and study the coupling between two whispering-gallery-mode microcavities through a side coupled fiber taper. The two microcavities can couple to each other bi-directionally with only one fiber taper waveguide due tomodal coupling between a pair of whispering-gallery mode starveling in opposite directions. By choosing appropriate physical parameters, some interesting spectra, such as electromagnetically-induced transparency-like coherent transmission and band-like refection, can be obtained in such a system. Slow light is discussed in this paper as a direct application of the coupled microresonator structure. This structure also has potential application in coupled cavity quantum electrodynamics.
"Static Envelope Patterns in Composite Resonances Generated by Level Crossing in Optical Toroidal Microcavities"
Tal Carmon, Harald G.L.Schwefel, Lan Yang, Mark Oxborrow, A. Douglas Stone, and Kerry J. Vahala
Phy. Rev. Lett. 100, 103905 (2008)
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.
2007 and before
"Perturbative analytic theory of an ultrahigh-Q toroidal microcavity"
Bumki Min,, Lan Yang, and Kerry Vahala
Phy. Rev. A. Vol. 76, p013823 (2007).
A perturbation theoretic approach is proposed as an efficient characterization tool for a tapered fiber coupled ultrahigh-quality factor (Q) toroidal microcavity with a small inverse aspect ratio. The Helmholtz equation with an assumption of quasi-TE/TM modes in local toroidal coordinates is solved via a power series expansion in terms of the inverse aspect ratio and the expanded eigenmode solutions are further manipulated iteratively to generate various characteristic metrics of the ultrahigh-Q toroidal microcavity coupled to a tapered fiber waveguide. Resonance wavelengths, free spectral ranges, cavity mode volumes, phase-matching conditions, and radiative Q factors are derived along with a mode characterization given by a characteristic equation. Calculated results are in excellent agreement with full vectorial finite-element simulations. The results are useful as a shortcut to avoid full numerical simulation, and also render intuitive insight into the modal properties of toroidal microcavities. The American Physical Society.
"Ultralow-threshold Yb:SiO 2 glass laser fabricated by the solgel process"
Eric Ostby, Lan Yang, and Kerry Vahala
Opt. Lett. Vol. 32, p 2650 (2007).
A Yb-doped silica microcavity laser on a silicon chip is fabricated from a solgel thin film. The high-Q microtoroid cavity, which has a finesse of 10,000, is evanescently coupled to an optical fiber taper. We report a threshold of 1.8 Î¼W absorbed power that is, to the best of our knowledge, the lowest published threshold to date for any Yb-doped laser. The effect of Yb 3+ concentration on laser threshold is experimentally quantified. 2007 Optical Society of America.
"Visible Submicron Microdisk Lasers"
Zhaoyu Zhang, Lan Yang, Victor Liu, Ting Hong, Kerry Vahala, Axel Scherer
App. Phy. Lett. Vol. 90, p 111119 (2007).
We describe the performance of submicron microdisk lasers fabricated within InGaP/InGaAlP quantum well material working at room temperature. The smallest lasers, with diameters of approximately 600 nm, feature ultrasmall mode volumes and exhibit single mode operation at low threshold powers. Their small cavity volumes of approximately 0.03 um3 enable microdisk lasers to be used as spectroscopic sources. Here the we demonstrate the fabrication and characterization of visible, monolithically fabricated, submicron microdisk lasers. 2007 American Institute of Physics.
"Ultralow threshold on-chip microcavity nanocrystal quantum dot lasers"
Bumki Min, Sungjee Kim, Koichi Okamoto, Lan Yang, Axel Scherer, Harry Atwater and Kerry Vahala
App. Phy. Lett. Vol. 89, p 191124 (2006).
Chemically synthesized nanocrystal, CdSe/ZnS (core/shell), quantum dots are coated on the surface of an ultrahigh-Q toroidal microcavity and the lasing is observed at room and liquid nitrogen temperature by pulsed excitation of quantum dots, either through tapered fiber or free space. Use of a tapered fiber coupling substantially lowered the threshold energy when compared with the case of free space excitation. The reason for the threshold reduction is attributed to the efficient delivery of pump pulses to the active gain region of the toroidal microcavity. Further threshold reduction was possible by quantum dot surface-coverage control. By decreasing the quantum dot numbers on the surface of the cavity, the threshold energy is further decreased down to 9.9 fJ. 2006 American Institute of Physics.
"Transmission characteristics of a Fabry-Perot etalon-microtoroid resonator coupled system"
Wei Liang, Lan Yang, Joyce Poon, Yanyi Huang, Kerry J. Vahala, and Amnon Yariv
Optics Lett. Vol. 31 (2006).
The transmission spectra of a Fabry-Perot etalon coupled to a microtoroid resonator are studied theoretically and experimentally. The resonance line shapes depend strongly on the resonance wavelength detuning and coupling strength between the two resonators. A wide variety of line shapes, ranging from a single to triple peaks, symmetric to asymmetric Fano-like peaks, and notches were predicted and observed experimentally. The capability to modify the spectral line shapes by tuning the coupling between or losses of two resonators may find applications in optical filtering, switching, sensing, and dispersion engineering. 2006 Optical Society of America.
"Controlled transition between parametric and Raman oscillations in ultra-high-Q silica toroidal microcavities"
Bumki. Min, Lan Yang, and Kerry J. Vahala
App. Phy. Lett., Vol. 87, p 181109 (2005).
A controllable and reversible transition between parametric and Raman oscillations in an ultrahigh-Q silica toroidal microcavity is experimentally demonstrated and theoretically analyzed. By direct change of cavity loading and indirect adjustment of frequency detuning, parametric and/or Raman oscillation can be accessed selectively without modification of cavity geometry in a toroidal microcavity with a large enough aspect ratio. Based on an effective cavity gain theory, this transition is analyzed in terms of cavity loading and frequency detuning leading to a better understanding of the combined effects of parametric and Raman processes in silica microcavities. 2005 American Institute of Physics.
"Erbium-doped and Raman microlasers on a silicon chip fabricated by the sol-gel process"
Lan Yang, Tal Carmon, B. Min, S. M. Spillane, and Kerry J. Vahala
App. Phy. Lett., Vol. 86, p 091114, 2005.
We report high-Q sol-gel microresonators on silicon chips, fabricated directly from a sol-gel layer deposited onto a silicon substrate. Quality factors as high as 2.5 X 10(7) at 1561 nm were obtained in toroidal microcavities formed of silica sol-gel, which allowed Raman lasing at absorbed pump powers below 1 mW. Additionally, Er3+-doped microlasers were fabricated from Er3+-doped sol-gel layers with control of the laser dynamics possible by varying the erbium concentration of the starting sol-gel material. Continuous lasing with a threshold of 660 dW for erbium-doped microlaser was also obtained. 2005 American Institute of Physics.
"Feedback control of ultra-high-Q microcavities: application to micro-Raman lasers and microparametric oscillators"
Tal Carmon, T. J. Kippenberg, Lan Yang, H. Rokhsari, S. M. Spillane, and Kerry J. Vahala
Opt. Express, Vol. 13, No. 9, p 3558, 2005.
We demonstrate locking of an on-chip, high-Q toroidal-cavity to a pump laser using two, distinct methods: coupled power stabilization and wavelength locking of pump laser to the microcavity. In addition to improvements in operation of previously demonstrated micro-Raman and micro-OPO lasers, these techniques have enabled observation of a continuous, cascaded nonlinear process in which photons generated by optical parametric oscillations (OPO) function as a pump for Raman lasing. Dynamical behavior of the feedback control systems is also shown including the interplay between the control loop and the thermal nonlinearity. The demonstrated stabilization loop is essential for studying generation of nonclassical states using a microcavity optical parametric oscillator. 2005 Optical Society of America.
"Temporal behavior of radiation-pressure-induced RF-oscillation of an optical microcavity photon mode"
Tal Carmon, H. Rokhsari, Lan Yang, T. J. Kippenberg, and Kerry J. Vahala
Phys. Rev. Lett., Vol. 94, p 223902, 2005.
We analyze experimentally and theoretically mechanical oscillation within an optical cavity stimulated by the pressure of circulating optical radiation. The resulting radio frequency cavity vibrations (phonon mode) cause modulation of the incident, continuous-wave (cw) input pump beam. Furthermore, with increasing cw pump power, an evolution from sinusoidal modulation to random oscillations is observed in the pump power coupled from the resonator. The temporal evolution with pump power is studied, and agreement was found with theory. In addition to applications in quantum optomechanics, the present work suggests that radiation-pressure-induced effects can establish a practical limit for the miniaturization of optical silica microcavities.
"Dynamical thermal behavior and thermal self-stability of microcavities"
Tal Carmon, Lan Yang, and Kerry J. Vahala
Opt. Express, Vol. 12, No. 20, P 4742, 2004.
As stability and continuous operation are important for almost any use of a microcavity, we demonstrate here experimentally and theoretically a self-stable equilibrium solution for a pump-microcavity system. In this stable equilibrium, intensity €" and wavelength-perturbations cause a small thermal resonant-drift that is enough to compensate for the perturbation (noises); consequently the cavity stays warm and loaded as perturbations are self compensated. We also compare here, our theoretical prediction for the thermal line broadening (and for the wavelength hysteretic response) to experimental results. 2004 Optical Society of America.
"Replica-molded high-Q polmer microresonators"
Andrea Martin, Deniz Armani, Lan Yang and Kerry J. Vahala
Opt. Lett., Vol. 29, No. 6, p533, 2004.
Ultrahigh-Q microtoroids on a chip are applied as replication masters to demonstrate replica-molded high-Q microresonator arrays. Replica Q factors are nearly material loss limited, affirming the integrity of the replication process, and are as high as 5 X 10(6), or nearly a factor of 40 greater than previous polymer-based devices. Because the molding process is nondestructive, both the master and the molds can be reused. Additionally, by using a novel optical polymer (Vicast), we demonstrate storage of high-Q microresonators in the mold for weeks, providing a method to preserve the whispering-gallery Q factor. 2004 Optical Society of America.
"Erbium-implanted High-Q silica toroidal microcavity laser on a silicon chip"
Bumki Min, T. J. Kippenberg, Lan Yang, K. J. Vahala, J. Kalkman, A. Polman
Phy. Rev. A., Vol. 70, No. 3, p033803, 2004.
Lasing from an erbium-doped high-Q silica toroidal microcavity coupled to a tapered optical fiber is demonstrated and analyzed. Average erbium ion concentrations were in the range 0.009-0.09 at. %, and a threshold power as low as 4.5 muW and an output lasing power as high as 39.4 muW are obtained from toroidal cavities with major diameters in the range 25-80 mum. Controlling lasing wavelength in a discrete way at each whispering-gallery mode was possible by changing the cavity loading, i.e., the distance between the tapered optical fiber and the microcavity. Analytic formulas predicting threshold power and differential slope efficiency are derived and their dependence on cavity loading, erbium ion concentration, and Q factor is analyzed. It is shown that the experimental results are in good agreement with the derived formulas.
"Fiber-coupled Erbium microlasers on a chip"
Lan Yang, Deniz Armani and Kerry J. Vahala
App. Phys. Lett., Vol. 83, No. 5, p 825, 2003.
An erbium-doped, toroid-shaped microlaser fabricated on a silicon chip is described and characterized. Erbium-doped sol-gel films are applied to the surface of a silica toroidal microresonator to create the microcavity lasers. Highly confined whispering gallery modes make possible single-mode and ultralow threshold microlasers. 2003 American Institute of Physics.
"Gain functionalization of a silica microresonators"
Lan Yang, and Kerry J. Vahala
Opt. Lett., Vol. 24, No. 8, p592, 2003.
Erbium-doped solgel films are applied to the surface of silica microspheres to create low-threshold microcavity lasers. This gain functionalization can be applied by use of a number of different dopants, thereby extending the wavelength range of this class of device. Also, by varying the doping concentration and thickness of the applied solgel layer, one can vary the laser dynamics so that both continuous-wave, and pulsating modes of operation are possible. 2003 Optical Society of America.
Prof. Lan Yang
Department of Electrical and Systems Engineering
- Campus Box 1042, Washington University
- Saint Louis, MO 63130
- Email: email@example.com
Phone: 314-935-9543, Fax: 314-935-7500