Depolarization compensation with a spatially variable wave plate in a 116  W, 441  fs, 1  MHz Yb:YAG double-pass laser amplifier

Abstract

A subpicosecond laser system featuring a fiber chirped pulse amplification-based seed laser and a double-pass end-pumped Yb:YAG crystal power amplifier was investigated. The key novelty of the system was the application of depolarization compensation using a specially designed spatially variable wave plate. To the best of our knowledge, this method was applied for the first time. The presented laser system produced pulses of 441 fs duration, 116 µJ pulse energy at 116 W average power with a beam quality of M 2 ∼ 2.1 , featured optical-to-optical efficiency of 32% at room temperature ( T = 20 ∘ C ), and had residual depolarization level of 2.7%.

10 mJ, 100 W, 1 ps hybrid laser system based on amplification in Yb:YAG

“…However, 12.3 % depolarization losses and thermally induced beam distortions require additional measures to improve spatial characteristics of the output beam. To compensate depolarization, a spatially variable waveplate can be used to reduce losses in a similar manner as it was demonstrated in our previous work 6 . Spatial filtering might be necessary to improve the output beam profile.…”

“…On the other hand, end-pumped rod-type Yb:YAG amplifier design is still attractive for power scaling above 100 W average power. Combined with techniques, such as along the side pumping 5 or depolarization compensation 6 , negative impact of the thermal effects can be minimized or compensated and good output beam parameters can be reached.…”

10 mJ-level Picosecond OPCPA Pump Laser Based on Room Temperature Hybrid Yb:YAG Amplifier System

“…Our aim is to create a compact and cost effective 100W-class, high energy laser system based on hybrid laser approach comprising fiber laser technology and free-space amplification combined with our patented thermal aberration management techniques [4]. During the first development stage we chose laser operation regime that allowed us to avoid polarization and beam distortions due to thermal effects and investigate amplification and nonlinear temporal pulse characteristics of the resulting laser radiation.…”