抄録
Optical frequency combs are widely used for metrology, optical clocks, optical communications and
sensors. In whispering gallery mode (WGM) microcavity resonators, geometrical features enable the
four-wave mixing phase match condition to be satisfied. Hence, frequency comb generation is
achievable. Geometrical dispersion of hollow structure WGM cavities can broaden the comb span to the
visible range.
