Cavity-length effects of high-temperature high-power continuous-wave characteristics in quantum-cascade lasers

We report the cavity-length dependent high-temperature high-power cw characteristics in λ=6 μm quantum-cascade lasers with a thick electroplated Au top contact layer. For a high-reflectivity (HR) coated 15 μm wide and 3 mm long laser, the cw operation is achieved up to 313 K (40 °C) with an output power of 17 mW. At 298 K, a very high cw output power of 213 mW is obtained for a HR coated 15 μm wide and 4 mm long laser. Thermal resistance is analyzed at temperatures above 283 K for HR coated lasers with different cavities.