Analysis of spontaneous Brillouin scattering spectrum for different modulated pulse shape

Effects of different modulated pulse shapes on the backscattered Brillouin power spectra are analyzed. The investigated pulse shapes include the Lorentzian, Gaussian, hyperbolic-secant, super Gaussian, triangular, and rectangular. With the same pulse width, the Lorentzian shape has the biggest peak value. The peak value of Brillouin scattering spectrum decreases and tends toward stability as the order of super Gaussian function increases. The physical mechanism is characterized by the difference of launched-pulse power spectrum. Experimental research on Lorentzian, Gaussian, and rectangular pulses has been undertaken; and results are in accordant with the numerical simulations.