A 2 μm Dual-Wavelength Laser at Cryogenic Temperature with Balanced Simultaneous Emission

A Tm,Ho:YAP laser at cryogenic temperature is demonstrated for the first time with simultaneous emission at 2000 nm and 2119 nm. The feasibility of switching wavelength and achieving balanced output powers at two widely separated wavelengths has been confirmed by investigating the temperature dependence of the laser spectra. The optimal temperature for balanced output evidently diminishes as the pump power density increases, thereby manifesting a rate of change quantified at 1.19 K/W. At the optimal temperature of 43.1 K, the optical-to-optical conversion efficiency of the Tm,Ho:YAP simultaneous dual-wavelength laser (SDWL) with a pump power of 11.8 W is 12.7%, corresponding to a slope efficiency of 15.8%.