High-average-power femtosecond laser at 258 nm

TL;DR

This paper reports a high-power femtosecond laser at 258 nm with 4.6 W average power, close to diffraction-limited beam quality, and discusses potential for further power scaling and pulse compression.

Contribution

The work demonstrates a novel high-power femtosecond laser at 258 nm using two-stage harmonic generation with detailed beam quality analysis.

Findings

Achieved 4.6 W average power at 258 nm

Beam quality close to diffraction limited (M2 ~1.3x1.6)

Potential for pulse compression to 40 fs

Abstract

We present an ultrafast fiber laser system delivering 4.6 W average power at 258 nm based on two-stage fourth-harmonic generation in beta barium borate (BBO). The beam quality is close to diffraction limited with an M2- value of 1.3 x 1.6. The pulse duration is 150 fs, which potentially is compressible down to 40 fs. A plain BBO and a Sapphire-BBO compound are compared with respect to the achievable beam quality in the conversion process. This laser is applicable in scientific and industrial fields. Further scaling to higher average power is discussed