# High power ultrafast phase-locked laser at 2060 nm from a doubly resonant optical parametric oscillator

## TL;DR

Researchers developed a high-power ultrafast laser at 2060 nm using a doubly resonant optical parametric oscillator, achieving record output power and efficiency.

## Contribution

This work demonstrates the highest output power and conversion efficiency for a degenerate BBO-based DROPO at 2 microns with active stabilization.

## Key findings

- The system achieves 5.6 W output power with 35% conversion efficiency using 15.8 W pump power.
- The laser shows excellent long-term stability with 0.78% RMS power noise over 90 minutes.

## Abstract

A high-power 2-\documentclass[12pt]{minimal}
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\begin{document}$$\mu$$\end{document}m phase-locked femtosecond source is demonstrated by a degenerate doubly resonant optical parametric oscillator (DROPO), which is synchronously pumped by a home-built Yb:YAG Kerr-lens mode-locked thin-disk laser. A dither-free scheme, incorporating an intracavity ’parasitic’ sum-frequency of signal and pump as an error signal, has been used to stabilize the DROPO at degeneracy. To our knowledge, with a pump power of 15.8 W, this system achieves the highest output power (5.6 W) and conversion efficiency (35 %) for an actively stabilized, degenerate BBO-based DROPO operating at 2 \documentclass[12pt]{minimal}
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\begin{document}$$\mu$$\end{document}m. The long-term stability measurement of the power over 90 minutes shows a root mean square (RMS) power noise of 0.78%, demonstrating excellent stability and reliable performance.