Crystalline Whispering Gallery Mode Resonators Research Articles

On the fundamental limits of Q factor of crystalline dielectric resonators

The temperature dependence of the processes which fundamentally limit optical quality factor of ideal crystalline whispering gallery mode resonators is investigated. The example of CaF(2) is used to show that spontaneous Raman scattering is the main limitation of the quality factor at low temperatures. Stimulated Raman scattering is also shown to be important at any temperature. We experimentally demonstrate nonlinear absorption due to stimulated Raman scattering in a real cavity at room temperature and theoretically derive Raman gain of CaF(2). We conclude that optical storage times in excess of one second could be achieved in millimeter sized cavities.

Parametric oscillations in a whispering gallery resonator

We demonstrate strongly nondegenerate optical continuous-wave parametric oscillations in crystalline whispering gallery mode resonators fabricated from LiNbO3. The required phase matching is achieved by geometrical confinement of the modes in the resonator.

Ultrahigh optical Q factors of crystalline resonators in the linear regime

Experimental demonstration of record optical quality factor of $(6.3\ifmmode\pm\else\textpm\fi{}0.8)\ifmmode\times\else\texttimes\fi{}{10}^{10}$ corresponding to cavity ring-down time of $\ensuremath{\tau}\ensuremath{\simeq}36\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{s}$ is made possible by avoiding nonlinear effects in a crystalline whispering gallery mode resonator. We discuss various loss mechanisms in $\mathrm{Ca}{\mathrm{F}}_{2}$ cavities and ways of achieving higher quality factors. Possible applications in quantum optics and photonics are discussed.