Fabrication and Test of Ultra-High Q Magnesium Fluoride Microdisk Resonator

Ultra-high quality factor whispering gallery mode crystal microresonators have promising applications in nonlinear optics, coherent optical communication, and microwave photonics. Improving the surface roughness to reduce the scattering loss is an effective way to improve the quality factor of magnesium fluoride (MaF(2)) crystal microdisk resonators. In this paper, we fabricated ultra-smooth MaF(2) crystal microdisk resonators with sub-nanometer surface roughness based on ultra-precision machining method, and the quality factor Q of MaF(2) crystal microdisk resonators in 1550 nm band is up to 1. 2x10(9) by using the tapered fiber coupling combined with cavity ringdown method, which helps to promote the research development in the field of ultra-high quality whispering gallery mode crystal microresonators in China.