# A high-power waveguide resonator second harmonic device with external conversion efficiency up to 75%

## TL;DR

This paper presents a highly efficient waveguide resonator device for second harmonic generation at 775 nm, achieving an external conversion efficiency of 75% and stable output power through cavity locking techniques.

## Contribution

It introduces a titanium indiffused LiNbO3 waveguide resonator with high conversion efficiency and stable operation using Pound-Drever-Hall locking.

## Key findings

- Achieved 75% external conversion efficiency.
- Produced up to 110 mW of second harmonic power.
- Maintained stable output power over one hour.

## Abstract

We report on a highly efficient waveguide resonator device for the production of 775 nm light using a titanium indiffused LiNbO3waveguide resonator. When scanning the resonance the device produces up to 110 mW of second harmonic power with 140 mW incident on the device - an external conversion efficiency of 75 %. The cavity length is also locked, using a Pound-Drever-Hall type locking scheme, involving feedback to either the cavity temperature or the laser frequency. With laser frequency feedback a stable output power of approximately 28 mW from a 52 mW pump is seen over one hour.