Compact, highly efficient, athermal, 25W, 2051nm Tm-fiber based MOPA for CO2 trace-gas laser space transmitter

A cladding-pumped polarization maintaining (PM) Thulium (Tm) fiber–based amplifier optimized for high efficiency and high power operation at 2051 nm is presented. The two-stage amplifier has been demonstrated to achieve 25 W average power, >16 dB polarization extinction ratio (PER) out of a single-mode PM fiber using a <500 kHz linewidth Jet Propulsion Laboratory (JPL) distributed feedback (DFB) laser1-3 and 43 dB gain. The power amplifier’s optical conversion efficiency is 53%. An internal efficiency of 58% is calculated after correcting for passive losses. The two-stage amplifier sustains its highly efficient operation for a temperature range of 5-40°C. The absence of stimulated Brillouin scattering (SBS) for the narrow linewidth amplification shows promise for further power scaling.