Multistage Smoothing Compressor for Multistep Pulse Compressors

Abstract

Ultrahigh peak-power lasers are important scientific tools for frontier laser physics research, in which both the peak power improvement and operating safety are very important. Based on spatial-chirp-induced beam smoothing in both the near field and far field, a multistage-smoothing-based multistep pulse compressor (MS-MPC) is proposed here to further improve safety and operating convenience. In the MS-MPC, beam smoothing is not simply executed in the pre-compressor or main compressor but is separated into multiple stages. As a result, important and expensive optics are directly protected in every stage. The prism-pair-based pre-compressor induces a small spatial chirp, making it both easier to achieve than the previous multistep pulse compressor and sufficient to protect the first grating directly. Furthermore, the asymmetric four-grating compressor, which serves as the main compressor, induces a spatial chirp that further smooths the laser beam, protecting the last grating. In this way, a 10 s to 100 s petawatt laser pulse can be compressed with a single laser beam using the currently available optics. Additionally, an extra beam-smoothing stage can be added before the main amplifier to safeguard the largest amplification crystal from damage. The MS-MPC can be easily integrated into all existing PW laser facilities to improve their potential compressed pulse energy and operational safety.