High-Q concentrated directional emission from egg-shaped asymmetric resonant cavities

Abstract

We propose the use of egg-shaped asymmetric resonant cavities (ARCs), each of which consists of a half-circular part and a half-deformed part, as promising candidates in obtaining desirable whispering-gallery-mode resonances. According to numerical analysis based on a ray-optics model, more than an order-of-magnitude higher Q and more-concentrated emission from the tip of the egg region were obtained for egg-shaped ARCs than for the previously studied quadrupolar ARCs.

Controlling deformation in a high quality factor silica microsphere toward single directional emission

“…These deformed microresonators can support directional emission modes, which provide an easy way to excite and detect cavity mode via free space. Various shapes of asymmetric resonant cavities, such as quadrupole [3][4][5], microstadium [6][7][8], egg-shaped [9], limaconshaped [10,11], Gibbous-shaped [12], and spiralshaped microcavity [13,14] have been intensively investigated both theoretically and experimentally in the past few years. The microresonators, combined with highly directional emission and ultrahigh quality factor, have been thought to be promising candidates for ultralow threshold microlasing and controllable single photon source.…”

Nanometer-scale resonant cavities

“…This type of resonator normally consists of an axially or spherically symmetric dielectric with a higher index of refraction than that of the surrounding medium and has a diameter comparable to or larger than the laser wavelength. In such resonators, the coupling of the gain medium can be limited to only a few discrete modes, specifically, the so-called whispering-gallery modes (WGMs) that have very high quality factor (Q) and very low threshold because of repeated total internal reflection [5][6][7][8]. In such a mode, light circulates around the curved inner boundary of the resonator, reflecting from the walls of the resonator with an angle of incidence always greater than the critical angle for total internal reflection.…”

Tuning of optical resonances in asymmetric microtube cavities

“…Recently, photonic devices such as wavelength-tunable emitters [10], microtube lasers [11], and passive filters [12] have been realized by using GaAs-based microtubes as core components. Other interesting aspects and phenomena, such as directional light emission [13] and enhanced coupling of ring resonators [14], might be feasible by deliberately introducing asymmetry into the structure.…”