Over 60% Optical-to-Optical Conversion Efficiency Linearly Polarized Single-Frequency Fiber Laser Based on Yb: YAG Crystal-Derived Silica Fiber

Silica optical fiber derived from yttrium-aluminum-garnet (YAG) crystals is an excellent high-gain fiber due to their high rare earth ions doping concentration. It offers a new opportunity of addressing the constraints on optical-to-optical conversion efficiency and output power in silica gain fiber-based linearly polarized single-frequency fiber lasers (LPSFFLs). Here, we fabricated a 6.57 wt.% Yb: YAG crystal-derived silica fiber (YCDSF) with a gain coefficient of 6.0 dB/cm at 1030 nm. Using a 0.8-cm-long YCDSF, a stable LPSFFL has been constructed, having an output power of over 350 mW and an optical-to-optical conversion efficiency as high as 63.0%. Among the similar YCDSF-based SFFLs, it has the highest output power and the largest conversion efficiency, to the best of our knowledge. By controlling the polarization state in the cavity, the optimum performances of the laser were accomplished with a relative intensity noise of <−143.5 dB/Hz, and a polarization extinction ratio of >21 dB. The approach presented here could be applicable to other RE: YAG crystal-derived silica fibers-based LPSFFLs operating at different wavelengths, paving the way for their applications in areas such as industrial processing, bioanalytic, metrology, and precision detection.