Single-mode oscillations of diode-pumped mid-infrared Er:Y₂O₃ ceramic microchip lasers at 2.7 μm

Two compact mid-infrared microchip lasers at 2717 and 2740 nm have been demonstrated using a Er:Y₂O₃ ceramic as laser gain medium with thickness of 800 μm, for the first time to our knowledge. Under a 976-nm diode laser pumping, the 2717 nm microchip laser with linewidth of about 0.16 nm is achieved with a maximum output power of 234.8 mW and slope efficiency of about 10.9%. The laser beam quality expressed by M² factor is measured to be about 1.23 and 1.45 in x and y directions. A single wavelength at 2740 nm with linewidth of about 0.15 nm is also achieved with maximum output power of 102 mW and slope efficiency of about 4.9%. Beam quality of the 2740 nm laser is found to be about 1.15 and 1.26 in x and y directions. Using a mechanical chopper to modulate the pump laser for thermal mitigation, the maximum output powers can be further improved to 312 mW for 2717 nm laser and 145 mW for 2740 m laser at higher pump powers. Such a mid-infrared microchip laser source with very compact size could be have great potential in various eye-safety-related applications.