Andrey B. Matsko

Optical resonators with whispering-gallery modes-part I: basics

We briefly review basic properties of dielectric whispering gallery mode resonators that are important for applications of the resonators in optics and photonics.

Optical resonators with whispering-gallery modes-part II: applications

We review photonic applications of dielectric whispering-gallery mode (WGM) resonators-tracing the growth of the technology from experiments with levitating droplets of aerosols to ultrahigh-Q solid state crystalline and integrated on-chip microresonators.

Tunable Optical Frequency Comb with a Crystalline Whispering Gallery Mode Resonator

We report on the experimental demonstration of a tunable monolithic optical frequency comb generator. The device is based on four-wave mixing in a crystalline calcium fluoride whispering gallery mode resonator. The frequency spacing of the comb is given by an integer number of the free spectral range of the resonator. We select the desired number by tuning the frequency of the pumping laser with respect to the corresponding resonator mode. We also observe a rich variety of optical combs and high-frequency hyperparametric oscillation, depending on the experimental conditions. A potential application of the comb for generating tunable narrow band frequency microwave signals is demonstrated.

Optical resonators with ten million finesse

We report a significant improvement of the finesse and quality factor of a calcium fluoride whispering gallery mode optical resonator achieved with iterative thermal annealing. The initial and final values of the resonator finesse are F(i) approximately 5 x 10(5) and F(f) >/= 10(7) respectively. The measurements are conducted at room temperature in the laboratory atmosphere.

Tunable delay line with interacting whispering-gallery-mode resonators

We theoretically study a parallel configuration of two interacting whispering-gallery-mode optical resonators and show a narrowband modal structure as a basis for a widely tunable delay line. For the optimum coupling configuration the system can possess an unusually narrow spectral feature with a much narrower bandwidth than the loaded bandwidth of each individual resonator. The effect has a direct analogy with the phenomenon of electromagnetically induced transparency in quantum systems for which the interference of spontaneous emission results in ultranarrow resonances.

Brillouin Lasing with a CaF2 Whispering Gallery Mode Resonator

Stimulated Brillouin scattering with both pump and Stokes beams in resonance with whispering gallery modes of an ultrahigh Q calcium fluoride resonator is demonstrated for the first time. The resonator is pumped with 1064 nm light and has 3 muW Brillouin lasing threshold. The scattering is observed due to the unique morphology of the resonator reducing the phase mismatch between the optical modes and the hypersound wave.

Mode-locked Kerr frequency combs

We analyze a mode-locked regime in Kerr frequency combs generated in nonlinear microresonators. Using damped driven nonlinear Schrödinger equations we show that the combs can produce subpicosecond optical pulses when the resonators are characterized with a small enough anomalous group velocity dispersion. We provide an analytical solution of the problem for the case of small damping.

Whispering-gallery-mode-resonator-based ultranarrow linewidth external-cavity semiconductor laser

We demonstrate a miniature self-injection locked distributed-feedback laser using resonant optical feedback from a high-Q crystalline whispering-gallery-mode resonator. The linewidth reduction factor is greater than 10,000, with resultant instantaneous linewidth of less than 200 Hz. The minimal value of the Allan deviation for the laser-frequency stability is 3 x 10(-12) at the integration time of 20 micros. The laser possesses excellent spectral purity and good long-term stability.

Whispering-gallery-mode resonators as frequency references. I. Fundamental limitations

We discuss thermodynamic as well as quantum limitations of the stability of resonance frequencies of solid-state whispering-gallery-mode resonators. We show that the relative frequency stability of a millimeter scale resonator can reach one part per 10−12 per 1 s integration time.

Whispering gallery mode based optoelectronic microwave oscillator

Abstract Properties of the optoelectronic microwave oscillator (OEO) based on an optical whispering gallery mode lithium niobate disc cavity are studied theoretically. We show that the threshold of the oscillation of this device may be as low as 1 mW, and its frequency stability (Allan deviation) may be as small as 10−15/t 1/2 for reasonable experimental conditions. The properties of resonant and non-resonant OEOs are compared. Preliminary experimental results on the whispering gallery mode OEO are reported.