Suppression of FM-to-AM conversion in third-harmonic generation by tuning the ratio of modulation depth

TL;DR

This paper investigates how tuning the ratio of modulation depths can suppress FM-to-AM conversion in phase-modulated third-harmonic generation, providing a theoretical expression and simulation validation for effective suppression.

Contribution

The study derives a theoretical expression relating group-velocity to modulation depth ratio to suppress FM-to-AM conversion in THG.

Findings

Suppression of FM-to-AM conversion achieved by tuning modulation depth ratio.

Derived a group-velocity expression to minimize AM in THG.

Simulation confirms effective suppression when the expression is satisfied.

Abstract

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.