Enhancement of Second-Harmonic Generation by Helicoidal Distributed Feedback Action in a Ferroelectric Liquid Crystal

Abstract

In a ferroelectric liquid crystal,a special type of phase-matching for optical second harmonic generation (SHG) is possible,where two counter-propagating fundamental waves create second harmonic waves at the edge of the selective reflection band. A remarkable enhancement of second harmonic generation by helicoidal distributed feedback action was observed ,which is proportional to a fourth power of the sample thickness, and is much larger compared with the conventional phase matched SH signal in rclative thick samples.