Low SBS passive optical fibers for fiber laser pigtails, components, and power delivery

Abstract

With narrow linewidth fiber lasers steadily increasing in power, it becomes important to consider the passive fibers employed as fiber laser pigtails, component fibers, power delivery fibers, etc. Stimulated Brillouin scattering (SBS) can become the leading power impairment in systems incorporating 'reasonable' lengths of passive fiber. For example, this might be a 1-meter passive fiber pigtail on a long-pulse transform-limited fiber amplifier. We present some results towards the development of large-scale (>10 dB) SBS-suppressed passive fibers for these applications. The results of several developed fibers will be shown, including optical fibers that exhibit large-scale SBS suppression (>10dB), with one fiber having a Brillouin gain coefficient as low as 0.15 × 10^-11 m/W in the core. Some fibers are found to be limited by SBS in the cladding. As a result, we incorporate more complete SBS-suppression approaches that also take the cladding interaction into consideration. We analyze both the Brillouin spectra and power transmission properties of several developed fibers to verify SBS suppression. Brillouin spectra are obtained through a standard heterodyne technique, while power transmission tests are compared against standard Ge-doped telecommunications fiber as a control. Modeling results will be shown to be in excellent agreement with experimental data.