Nonlinear and quantum optics with whispering gallery resonators

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.

Dielectric tuning and coupling of whispering gallery modes using an anisotropic prism

“…Whispering gallery mode (WGM) resonators are a powerful and versatile tool in modern day optics and have found great employ as novel light sources [1][2][3][4], in spectroscopic studies [5], frequency comb generation [6,7], quantum electrodynamics [8,9], sensing [10], nonlinear optics [11,12] and optomechanics [13,14]. Such extensive usage derives from the narrow bandwidths, high field strengths and small modal volumes boasted by WGMs.…”

“…Several numerical and approximate analytic techniques have been developed to study the properties of WGMs in the presence of local dielectric or plasmonic perturbations [32][33][34][35] and to model cavitywaveguide coupling [36][37][38][39][40]. To date, however, limited consideration has been given to birefringent resonators or couplers which are attracting increasing attention, especially in nonlinear optics [12,41]. In this work, we present a detailed theoretical formalism describing dielectric frequency tuning of WGM resonances using planar substrates, in addition to quantifying substrate induced line width changes .…”

Coherent Conversion Between Microwave and Optical Photons—An Overview of Physical Implementations

“…WGMs are formed when light propagates along a closed loop formed by a step change in refractive index. Typically, this is either a circular disk or microdisk, or a spheroid of a dielectric material in air or vacuum. Modes are denoted by angular ( m ), radial ( q ), and polar ( p ) indices, and both transverse–electric (TE) and transverse–magnetic (TM) mode families are supported.…”

Hyperspectral Nonlinear Optical Light Generation from a Monolithic GaN Microcavity

“…[24,25] It results in a wider tunability of the fundamental mode at the SHG frequency in the hexagonal resonator that is not feasible in bulk crystals. The hexagonal microcavity prefers modes with 60° angle of incidence within the cavity and reduces the mode degeneracy that can also result in non-WG modes such as the six bounce modes.…”

“…The high Q-factor and small interaction volume yield very high nonlinear conversion efficiency in hexagonal resonators. [24,25] It results in a wider tunability of the fundamental mode at the SHG frequency in the hexagonal resonator that is not feasible in bulk crystals. Semiconductor cavities with varying diameters also showed different WGMs.…”