Femtosecond thin disk laser oscillator with pulse energy beyond the 10-microjoule level

S V Marchese,A G Engqvist,D J Maas,C R Baer,M Golling,S Hashimoto,U Keller,T Südmeyer

doi:10.1364/oe.16.006397

Abstract

We report on a passively mode-locked Yb:YAG thin disk laser oscillator that generates 11.3-microJ pulses without the use of any additional external amplification. A repetition rate of 4 MHz is obtained using a 23.4-m-long multiple-pass cavity that extends the resonator length to a total of 37 m. The nearly transform-limited pulses at 45 W of average output power have a duration of 791 fs with a 1.56-nm-broad spectrum centered at 1030 nm. The laser is operated in a helium atmosphere to eliminate the air nonlinearity inside the resonator that previously limited the pulse energy.

Highlights

Femtosecond sources with microjoule-level pulse energies are interesting for many scientific and industrial applications
With the introduction of the thin disk laser [3], high average powers became possible in a power-scalable concept with excellent beam quality, the latter being a requirement for stable passive mode locking using semiconductor saturable absorber mirrors (SESAM) [4,5]
With the above-described experimental setup, we obtain stable passive mode locking at a repetition rate of 4 MHz with 45 W of average output power when the laser is operated in the box flooded with helium

Summary

Introduction

Femtosecond sources with microjoule-level pulse energies are interesting for many scientific and industrial applications. With the introduction of the thin disk laser [3], high average powers became possible in a power-scalable concept with excellent beam quality, the latter being a requirement for stable passive mode locking using semiconductor saturable absorber mirrors (SESAM) [4,5]. This combination resulted in femtosecond oscillators capable of directly generating microjoule-level pulse energies at multi-megahertz repetition rates with average powers of up to 80 W [6,7,8]. Higher pulse energies of 50 μJ at megahertz repetition rates have only been obtained using complex fiber amplifier systems [12]

Methods

Results

Conclusion