Experimental Investigation of Silicate-Glass-Based Raman Gain Fibers with Enhanced SBS Suppression by Selective Transverse Doping

Germanosilicate and phosphosilicate-based glasses are two of the most common materials used to amplify light in the near and shortwave infrared wavelengths by stimulated Raman scattering in optical fiber, but are limited in total output power and efficiency that can be achieved due to the onset of stimulated Brillouin scattering (SBS). We experimentally investigate both germanosilicate and phosphosilicate Raman gain fibers with selective transverse doping profiles in the context of altering the fiber acoustic waveguide properties for increasing the threshold at which total Raman amplified power is saturated by SBS. It is shown that selective transverse doping offers greater potential for SBS suppression in germanosilicate gain fibers in contrast to those manufactured from phosphosilicate glasses. Initial SBS suppressed germanoslicate fibers are demonstrated with a 5 to 6 dB reduction in the maximum peak Brillouin gain as compared to a standard step-index fiber such as Corning HI-1060, which allows for over 5 dB in SBS suppression and an increase in saturated Raman amplifier gain from 15 dB to greater than 22 dB.