Multiphysics model of liquid-cooled Nd:phosphate split-slabs in large aperture optical amplifiers.

High repetition rates in high energy solid-state laser systems can yield to a rise of temperature in amplifiers despite the use of cooling systems. This effect can significantly impact the performance of amplifiers by inducing thermal stress, birefringence or thermal lensing. Here, we develop a multiphysics model to support the design, optimization and commissioning of a liquid-cooled large aperture split-slab laser glass amplifier.

Nonlinear FM-AM conversion due to stimulated Brillouin scattering.

We report an effect potentially harmful occurring in regenerative amplifiers due to stimulated Brillouin scattering (SBS). Most high energy laser facilities use phase-modulated pulses to prevent the transverse SBS effect in large optical components and to smooth the focal spot on target. However, this kind of pulse format may undergo a detrimental effect known as frequency modulation to amplitude modulation (FM-AM) conversion in the presence of spectral distortions.

Laser-induced damage of fused silica optics at 355 nm due to backward stimulated Brillouin scattering: experimental and theoretical results.

Forward pump pulses with nanosecond duration are able to generate an acoustic wave via electrostriction through a few centimeters of bulk silica. Part of the incident energy is then scattered back on this sound wave, creating a backward Stokes pulse. This phenomenon known as stimulated Brillouin scattering (SBS) might induce first energy-loss, variable change of the temporal waveform depending on the location in the spatial profile making accurate metrology impossible, and moreover it might also initiate front surface damage making the optics unusable.