Temporal, Spectral and Spatial Characterization of High-Energy Laser Pulse with Small Bandwidth Propagating through Long Path

Abstract

Temporal, spectral and spatial characters of 0.3-nm-bandwidth high-energy laser pulse propagating through a long path are studied in detail in one newly constructed beamline of our laser facility. The evolution of propagation, pulse energy and near-field deterioration are analyzed theoretically and experimentally. Substituting argon for air is demonstrated effectively to suppress stimulated rotational Raman scattering and the experimental result provides operating criterion, and engineering parameters for the under-constructed beamlines.

Surface phase defects induced downstream laser intensity modulation in high-power laser facility

“…As shown in Figure 2, some fringe-like phase defects are clearly observed with a modulation depth of about several tens of nanometers. Typically, there are six or seven reflecting mirrors in our laser facility [10] , supporting the lasers propagating to the FOA. The observed phase defects exist on the first and the third mirror, respectively.…”

Raman Suppression in a Kilowatt Narrow-Band Fiber Amplifier

“…However, the output powers of these narrow-band fiber systems are limited to kW-level. For the strong power density and long interaction length, the onset of undesired nonlinear effects becomes the main limiting factor, [7] especially the stimulated Raman scattering (SRS) due to the fact that it normally presents the lowest onset threshold while the stimulated Brillouin scattering (SBS) can be ignored in lasers with tens of GHz linewidths. [8] Thus controlling or suppressing SRS becomes essential as power exceeds a certain threshold, the SRS in fibers can convert part of the signal into undesirable longer-wavelength Raman Stokes waves in the forward and backward directions, hence degrading the laser efficiency.…”