Pulse cumulative effect on third harmonic generation from femtosecond laser filament in air

This study explores the pulse cumulative effect on third harmonic generation within femtosecond laser filaments in air. By measuring the third harmonic spectrum at different repetition rates, we observe that the spectrum of the third harmonic broadens in the long-wave direction and its intensity increases as the laser repetition rates increases.本研究针对空气中飞秒激光丝（femtosecond laser filaments）内部的三次谐波产生（third harmonic generation）过程所受的脉冲累积效应（pulse cumulative effect）展开探究。通过在不同激光重复频率下测量三次谐波光谱，我们观测到：随着激光重复频率升高，三次谐波光谱会向长波方向展宽，且其强度同步提升。