Suppression of FM-to-AM conversion in third-harmonic generation by   tuning the ratio of modulation depth
  Issues of Frequency-to-Amplitude modulation (FM-to-AM) conversion occurred in phase-modulated third-harmonic generation (THG) process are investigated. An expression about group-velocity is theoretically derived to suppress the FM-to-AM conversion, which appears to be dependant on the ratio of modulation depth of fundamental to second-harmonic when given the same modulation frequencies of them. Simulation results indicate that the induced AM in THG process can be suppressed effectively when the expression about group-velocity is satisfied. 
Yisheng Yang, Yizhou Tan, Bin Feng, Fuquan Li, Wei Han, and Jichun Tan
physics.optics