Open AccessExperimental analysis on CPA-free thin-disk multipass amplifiers operated in a helium-rich atmosphere
Author(s) -
Florian Bienert,
André Loescher,
Christoph Röcker,
Thomas Graf,
Marwan Abdou Ahmed
Publication year - 2022
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.469697
Subject(s) - helium , amplifier , optics , materials science , atmosphere (unit) , laser , wavelength , beam (structure) , physics , atomic physics , optoelectronics , meteorology , cmos
We present an experimental investigation on the benefits of helium as an atmospheric gas in CPA-free thin-disk multipass amplifiers (TDMPAs) for the amplification to average powers exceeding 1 kW and pulse peak powers reaching 5 GW. Both the performance of the amplifier and the properties of the amplified sub-400 fs laser pulses centred at a wavelength of 1030 nm are compared for different helium concentrations in air, outlining and quantifying the benefits of a helium-rich atmosphere. The amplification of 100 µJ pulses in an atmosphere with 60% helium instead of air led to a maximum increase in efficiency from 24% to 29%. This translated into an increase of average output power and pulse energy of 34 W (i.e +19%) and 0.34 mJ (i.e. +19%) respectively. At the same time an improvement of the beam quality from M 2 = 1.18 to M 2 = 1.14 was achieved. For the amplification of 10 µJ pulses to over 1 kW of average power an atmosphere with 33% helium led to an improved beam pointing stability by a factor of 2. Moreover, the beam propagation factor M 2 improved by 0.1, and the power stability improved by approximately 10%.