The experimental study on pump influence of a multi-wavelength Brillouin fiber laser with switchable frequency spacing

Abstract

An experimental study of the pump influence upon a multi-wavelength Brillouin fiber laser (MW-BFL) of switchable Brillouin Stokes generation is presented. The bi-directional ring cavity in the MW-BFL is comprised of a piece of 20-km single-mode fiber to provide the Brillouin gain. We investigate the major pump parameters including the Brillouin pump (BP) ratio into the ring cavity, the initial BP power, and the primary pump power for their effectiveness on the switchable-spaced Brillouin generation. The optical signal to noise discrepancy (OSNRD) between the adjacent odd and even Stokes lines is evaluated as the main indicator. The optimal BP coupling ratio is found as 90/10 for the proposed scheme. Four Brillouin lasing lines with single frequency shift of 10.75 GHz and one Brillouin lasing line with double Brillouin shift of 21.51 GHz have been observed when the input BP power is at −5 dBm and 4 dBm, respectively. An appreciable OSNRD is obtained accordingly, which is 0.6 dB for the single-spaced spectrum and 18.6 dB for the double-spaced spectrum.