Lamp-pumped eight-pass neodymium glass laser amplifier with high beam quality

Abstract

This study presents a lamp-pumped Nd:glass laser system capable of achieving joule level output energy at 1-Hz repetition rate with high beam quality. The 1.8 J of energy in a 5 ns pulse was achieved with 1.5 mJ injected energy. The laser system includes a beam shaping module and an eight-pass, lamp-pumped amplifier. The laser amplifier demonstrated longterm energy stability of 1.76% PV and 0.29% RMS when operating at 1.8 J for 30 minutes. In a longer period of operation, no damage or obvious beam degradation was found. A uniform gain distribution with a single-pass small-signal gain of 3.89 was acquired with the four-lamp-pumping method, and thermally induced wavefront aberration was mitigated. Finally, a high beam quality was obtained using a homemade optically addressed liquid crystal light valve. After compensation, the near-field modulation decreased from 1.38 to 1.21, meanwhile, the beam contrast decreased from 6.54 to 4.71%. In terms of the far-field quality, a 90% far-field energy concentration was 2.5 times the diffraction limit.

Automated Long-Term Stability of a High-Energy Laser

“…Moreover, we can envision that this same system could be applied to a wide range of lasers as long as they are not single-shot lasers. In fact, applications from 3D printing [10] to laser plasma accelerators [11] or shearography [12] imply a careful control of the laser energy; this is especially problematic for low-repetitionrate, high-energy lasers [13,14] that perform intricate, highly nonlinear physics at the same time as comporting a high thermal load that is due to changes in the environment, and also due to the heating of the laser components during pumping. A full description of the sub-system this pump laser is included in can be found in [2].…”