Over 300 mW Single-frequency Distributed Bragg Reflector Fiber Laser at 2.04 μm Based on Tm:YAG/Ho:YAG Co-derived Silica Fiber

Several Tm:YAG/Ho:YAG co-derived silica fibers (THCDSFs) were fabricated using the molten core (MC) method. A maximum gain coefficient of 5.16 dB/cm at 2040 nm was obtained for the THCDSF prepared through the utilization of a spliced piece of semi-cylindrical 15.0 at% Tm:YAG and 2.5 at% Ho:YAG crystals as the core precursor material. Employing a 2.0-cm-long THCDSF and in-band pumping with a 1610 nm fiber laser, a stable single-frequency distributed Bragg reflector (DBR) laser operating at 2040 nm was demonstrated. The fiber laser has a maximum output power of 306 mW and a slope efficiency of 19.3% for the absorbed pump power. To the best of our knowledge, this represents the maximum recorded output power of a single-frequency DBR short-cavity laser oscillator above 2 μm to be reported.