Stimulated rotational Raman scattering (SRRS) limits the effective transmission distances of the high-energy and high-power laser pulses in laser–fusion systems and other applications. A simple and practical method of suppressing SRRS process by controlling the polarization direction of Stokes light is proposed. For a narrowband, linearly polarized, flat-topped laser pulse of 351 nm with intensity of 2 GW/cm2 and width of 3 ns, the SRRS threshold distance in air is lengthened to 30.0 m from 16.2 m easily using the method. Simulation results demonstrate that the method is also applicable for broadband laser.

The effect of smoothing by spectral dispersion (SSD) on stimulated rotational Raman scattering (SRRS) in air has been investigated both numerically and theoretically. The suppression effect of SSD on SRRS process is verified and it is demonstrated and proposed that the suppression effect is attributed to two aspects: the decreasing of the laser fluence modulation degree and the reducing of Stokes gain coefficient caused by the temporal and spatial variation of the phase of the incident laser pulse. The simulation results show that the SRRS threshold distance can be lengthened by choosing appropriate SSD parameters.