Watt-level, high-efficiency single-frequency DBR Tm³⁺-doped YAG crystal-derived silica fiber laser oscillator at...

A watt-level, high-efficiency single-frequency distributed Bragg reflector (DBR) fiber laser emitting at 1941 nm was demonstrated using a Tm³⁺-doped yttrium aluminum garnet (Tm:YAG) crystal-derived silica fiber (TYCDSF). The TYCDSF, featuring a core doping concentration of Tm₂O₃ as high as ∼12.17 wt.% and a gain coefficient of 5.10 dB/cm at 1941 nm, was fabricated through the molten core method (MCM). By employing a 16-mm-long TYCDSF and in-band core pumping with a 1610 nm fiber laser, a stable single-frequency laser with a maximum output power of 1030 mW and a slope efficiency of 50.83% for absorbed pump power was achieved. The laser exhibited an optical signal-to-noise ratio exceeding 66.5 dB and a laser linewidth of approximately 40.75 kHz. To the best of our knowledge, this is the first demonstration of a watt-level single-frequency laser based on YAG crystal-derived silica fiber (YCDSF). Moreover, the slope efficiency achieved in this work is the highest reported for single-frequency lasers in the 2-μm band.