Single-Frequency Sub-kW-Peak-Power Combined Er/Er-Yb-Fibers Amplifier with a High Pump-to-Signal Conversion Efficiency

Abstract

Single-frequency high peak power pulsed lasers operating in the 1.55 μm spectral range are required in many applications such as wind sensing LIDAR and gas column sensing. When pulse duration exceeds 10–20 ns the main limitation for peak power comes from Stimulated Brillouin Scattering (SBS). To date the highest peak power in all-fiber single-mode laser scheme was demonstrated in [1] using Er-doped (Yb-free) double clad cladding pumped large mode area fiber (EDF). The maximum peak power above 4 kW was demonstrated, however the pump to signal conversion efficiency (PCE) was only 5% with respect to launched pump power. Increase of PCE to 12% was demonstrated in the same work using longer fiber, but peak power was decreased down to 950 W. Utilization of specialty technique for SBS suppression allows one to improve these results. In particular applying of gradient stress to large mode area Er-Yb fibers (EYDF) resulted in achievement of 1 kW peak power and 16.5% PCE [2].