High efficiency laser spatial beam smoothing based on stimulated Brillouin scattering

Abstract

In this paper we proposed and numerically demonstrated a novel scheme for spatial beam smoothing of high-power lasers based on stimulated Brillouin scattering (SBS). With the intensity dependent property of SBS, the higher intensity parts of the laser beam are reflected to a great extent when the other parts are transmitted through the medium with weak reflection. Then, the inputted non-uniform high-power laser beam is smoothed. As a numerically simulation experiment, the beam smoothing property of the proposed scheme was calculated in this paper. A pulsed single frequency laser was used as the pump, whose output pulse is 20th order super-Gaussian shaped with a duration of 3 ns, a beam diameter is 40 mm and a wavelength of 527 nm. The heavy fluorocarbon FC-40 was used as the nonlinear medium. The numerically calculated results indicate that the laser intensity modulation index can be greatly pulled down after passing through the Brillouin medium with a suitable laser intensity. The energy efficiency is above 90% when the laser beam is smoothed to the greatest extent.

Optimising of the material and laser parameters for high-power laser spatial beam smoothing based on stimulated Brillouin scattering

“…Temporal flattopped pulses have been generated experimentally [15], and we believe that the same results may be obtained in the spatial domain. In our recent work, the laser beam smoothing scheme base on SBS spatial power limiting has been numerically studied [18]. When a high-power laser with a non-uniform nearfield is injected into a Brillouin medium, the higher intensity parts of the laser beam are greatly reflected while the other parts experience weak reflection.…”

“…By numerically solving the coupled-wave equations ( 1)-( 3), we can model the SBS process when the pump is injected into the medium cell. The boundary conditions under which the SBS equations are solved have been detailed in our recent article [18]. During the numerical calculation, the split-step Fourier method is used.…”

Spatiotemporal shaping of high power laser pulses based on stimulated brillouin scattering

“…However, the total transmissivity of SLM devices is relatively low [7], and the beam quality is improved at the cost of the output energy. In our previous research, we proposed a more effective method based on SBS to enhance laser near-field uniformity with high energy transmittance [10,11]. SBS attracts extensive attention owing to its wide applications both in high quality laser generation [12][13][14][15], optical amplification [16,17] and distributed optical fiber sensing [18].…”