Nonlinear dynamics of optical frequency comb in the whispering gallery mode microcavity with higher-order effects.

Abstract

In this work, the optical field distribution of the optical frequency comb in the whispering gallery mode microcavity is demonstrated based on the coupled Lugiato-Lefever equation model with high-order dispersion, Raman and self-steepening effects, which effectively adjusts the phase-matching conditions of the optical field and the spectral envelope morphology inside the cavity, and inhibits the occurrence of the unstable state of the optical frequency comb. By exploring the effects of the frequency detuning and pump power on the spectral characteristics of optical frequency combs, it is found that the change in the frequency detuning and pump power affects the intensity of the optical field in the microcavity, which in turn changes the intensity distribution and spectral bandwidth of the optical frequency comb. The larger the pump power is, the larger the detuning tunable range is, and the detuning tunable range also adds with the increase in pump power. In addition, the frequency distribution of the mode in the optical frequency comb is effectively regulated and the stability is improved. The change in frequency also has a significant effect on the phase relationship between the modes and the uniformity of the frequency interval. The influence of the high-order effects on the optical frequency comb is also systematically studied. The balance between the Raman gain and the fourth-order dispersion can promote the mode locking and realize the stability of the frequency comb. The addition of the self-steepening effect causes the power in the cavity to oscillate within a certain range.