Development Of Ultra-High Quality Fluoride Optical Crystal Microdisk Resonators

Whispering gallery mode fluoride optical crystal microcavities offer unique values for applications in compact integrated optoelectronic oscillators and ultra-narrow linewidth lasers,owing to their ultra-high quality factor,small free spectral range,and low thermal noise.This thesis focuses on the preparation of fluoride optical crystal microdisk cavities,and the results of the corresponding research are as follows:Firstly,this thesis developed a high-precision and ultra-high-quality fabrication process for magnesium fluoride crystal microdisk cavities.Using this process,a magnesium fluoride microcavity with a free spectral range of 15.421 GHz was fabricated,with a deviation from the target free spectral range of only 0.51%(target value of 15.5 GHz).The quality factor reached 1.2×109 at a wavelength of 1550 nm.Secondly,this thesis fabricated a high-quality composite structure calcium fluoride crystal microdisk cavity.By combining the preparation process of the ultra-high-quality calcium fluoride crystal microcavity with the structural design of the zero-expansion calcium fluoride composite microcavity,a zero-expansion calcium fluoride composite structure microdisk cavity with a quality factor of 6×108 at a wavelength of 1550 nm was prepared.This lays a foundation for reducing the thermal instability of the resonant frequency of the calcium fluoride microcavity.