Grating-Induced Slow-Light Enhancement of Second Harmonic Generation in Periodically Poled Crystals

TL;DR

This paper demonstrates theoretically that slow-light effects in periodically poled nonlinear crystals can significantly enhance second harmonic generation efficiency, achieving nearly 100% conversion with low-intensity continuous wave pumping.

Contribution

It introduces a novel approach using a linear phase-shifted grating to slow light and boost SHG efficiency in periodically poled crystals, a significant improvement over previous methods.

Findings

Near 100% SHG conversion efficiency achieved

Slow light enhances field intensity and conversion efficiency

Low-intensity CW pumping suffices for high conversion

Abstract

The effect of slow light on second harmonic generation in a periodically poled $\chi^{(2)}$ nonlinear medium is investigated theoretically. A linear $\pi$ phase shifted grating is used to slow the group velocity of the fundamental frequency and the resulting field enhancement greatly increases the second harmonic conversion efficiency. A second linear grating at the input end ensures that all output is in the forward direction. We show that almost 100\% conversion efficiency can be achieved for continuous wave pumping at low intensities that generate negligible conversion in the absence of the slow-light grating.