Single domain wall effect on parametric processes via Cherenkov-type phase matching

TL;DR

This paper investigates how a single domain wall in ferroelectric crystals influences parametric nonlinear optical processes through Cherenkov-type phase matching, leading to novel effects like Cherenkov second harmonic generation.

Contribution

It demonstrates the confinement of nonlinear polarization at a domain wall and introduces new Cherenkov-based parametric processes with enhanced nonlinear coefficients.

Findings

Observation of Cherenkov second harmonic generation in ferroelectric domain walls

Demonstration of complex DW-modulated parametric processes like sum frequency generation

Proposal of significantly enhanced nonlinear coefficients in domain walls

Abstract

We report on important influence of single domain wall (DW) of electrically poled ferroelectric crystal on parametric processes via Cherenkov-type phase matching. It shows that the effective nonlinear polarization is confined in DW and its phase velocity can be modulated when incident light is off domain wall's direction. These effects lead to novel Cherenkov second harmonic generation (CSHG) which has no analogue in bulk ferroelectrics. Complex DW-modulated parametric process via Cherenkov-type phase matching, such as Cherenkov sum frequency generation (CSFG), is also demonstrated in DW. We propose that nonlinear coefficient in DW is significantly enhanced.