CW frequency doubling of 1029 nm radiation Using single pass bulk and waveguide PPLN crystals

TL;DR

This study compares the efficiency of CW frequency doubling of 1029 nm radiation using bulk and waveguide PPLN crystals, highlighting the higher power output of waveguides but also their degradation issues.

Contribution

It provides a direct performance comparison between bulk and waveguide PPLN crystals for CW frequency doubling at 1029 nm, including practical efficiency and degradation insights.

Findings

Bulk crystal generated 4 mW from 400 mW IR input.

Waveguide crystal achieved 33 mW with 200 mW IR input.

Waveguide efficiency was compromised by long-term degradation.

Abstract

Following various works on second harmonic process using periodically poled Lithium Niobate crystals (PPLN), we report on the performances comparison between commercial bulk and waveguide crystals at 1029 nm. We use a continuous wave (CW) amplified Yb doped single fibre laser delivering up to 500mW in single mode regime. In case of bulk crystal we generate 4 mW using 400 mW IR power. The use of waveguide crystal leads to an increase of the harmonic power up to 33mW with input IR power limited to 200mW. Nevertheless, this impressive efficiency was affected by the long term degradation of the non-linear waveguide crystal.