Broadband pumping enabled flat-amplitude multi-wavelength random Raman fiber laser.

Abstract

A flat-amplitude multi-wavelength random Raman fiber laser with broad spectral coverage and a high optical signal-to-noise ratio (OSNR) is challenging and of great interest. In this Letter, we theoretically and experimentally proved that broadband pumping can help realize a broader, flat-amplitude multi-wavelength random Raman fiber laser. The influence of pump bandwidth, tunability of the spectral envelope, and channel spacing are investigated. As a result, with a 40 nm pump bandwidth, a spectral coverage of 1116-1125 nm with 19 laser lines and 31 dB OSNR is achieved, and the standard deviation in the peak intensities of the central nine lines is ${\sim}{1}.{1}\;{\rm dBm}$∼1.1dBm. This technique can also be applied to the multi-wavelength Raman (or random Raman) fiber lasers at other wavelengths and provide a reference for multi-wavelength applications in sensing, communication, and optical component testing.