Fabrication of millimeter-scale crystal whispering gallery mode resonators

Abstract

The Whispering Gallery Modes Resonators(WGMR) are specific electromagnetic modes confined in circular resonators, where light beams are guided along the circumferences of the resonators with very small losses by total internal reflections. WGMR is the core component of optical filters, ultra-narrow linewidth laser, microwave photoelectric oscillator, optical frequency comb, rubidium atomic clock etc and high-precision sensors. Q factor is defined as the ratio of the total energy of photons in WGMR to the loss lost in one propagation cycle. The energy loss of WGMR is discussed. The cutting dynamics model diagram was established based the cutting force model for turning. The key technology affecting WGMR’s Q factor was the fabrication process. The manufacture of ultra-high Q factor WGMR are realized through rough machining, ultra-precision turning and precision polishing. The processing of ultra-precision turning and precision polishing is reported in the paper. The important fabrication processing of WGMR is ultra-precision turning. The test results show that the Q value of WGMR is 1.5×10 9@1550nm by Q value measurement system. The surface roughness and shape error of WGMR are 0.6nm (Ra value) and 5.3nm (PV value) respectively, measured by white light interferometer.