Suppression of first order stimulated Raman scattering in erbium-doped fiber laser based LIDAR transmitters through induced bending loss

A model is presented for suppression of first-order stimulated Raman scattering (SRS) in pulsed Er-doped fiber amplifiers with wavelength-selective induced bending loss. The model estimates the effectiveness of SRS suppression through fiber coiling in a pulsed amplifier, considering both the single- and dual-clad fiber cases. The basic approach is to fit analytical expressions to the evolution of a quasi-CW signal in the amplifier. Then, assuming that SRS does not deplete the signal, exact analytical expressions for the propagation of the Stokes wave are determined, from which the SRS threshold is estimated. Finally, example calculations are presented, and the model is used to determine a fiber geometry for the suppression of SRS through fiber coiling.