Theoretical research on one-third harmonic generation process in optical microfibers

This work, based on third-order nonlinear coupled-mode equations, aims at analyzing the optimization in one-third harmonic generation processes with initial conditions, including the initial ratio of the incident light power, phase difference, diameter and effective length of silica microfibers. Through the application of the microfiber loop resonators to one-third harmonic generation process, we reduce the incident power threshold of seed light by tens orders, and increase the nonlinear effective interaction length by several hundreds of times. Theoretical calculation results show that the loop resonator can effectively enhance the conversion efficiency of one-third harmonic generation by 104 compared with the straight microfibers.