Fully-resonant, tunable, monolithic frequency conversion as a coherent UVA source

TL;DR

This paper presents a monolithic, tunable frequency converter capable of efficient continuous-wave second harmonic generation in the UVA range, with multiple tuning degrees of freedom and stability enhancements.

Contribution

It introduces a fully-resonant, tunable, monolithic frequency conversion device with four tuning parameters, achieving high efficiency and stability for UVA light generation.

Findings

Achieved 72%/W efficiency in second harmonic generation.

Demonstrated simultaneous resonance and phase-matching with multiple tuning degrees.

Observed optical bistability and its potential for output stabilization.

Abstract

We demonstrate a monolithic frequency converter incorporating up to four tuning degrees of freedom, three temperature and one strain, allowing resonance of pump and generated wavelengths simultaneous with optimal phase-matching. With a Rb-doped periodically-poled potassium titanyl phosphate (KTP) implementation, we demonstrate efficient continuous-wave second harmonic generation from 795 nm to 397 nm, with low-power efficiency of 72%/W and high-power slope efficiency of 4.5%. The measured performance shows good agreement with theoretical modeling of the device. We measure optical bistability effects, and show how they can be used to improve the stability of the output against pump frequency and amplitude variations.