Low-threshold and high power λ∼9.0 μm quantum cascade lasers operating at room temperature

We report a low threshold current density and high power for $\text{λ∼9\hspace{0.05em}μ}\mathrm{mAlInAs/GaInAs}$ quantum cascade lasers operating at room temperature. The threshold current density is 1.95 kA/cm² at 300 K and 0.61 kA/cm² at 80 K for 5 μs pulses at 200 Hz repetition rate. The peak output power is 700 mW at room temperature and 1.3 W at 80 K per two facets for cavity length is 3 mm with a stripe width of 20 μm. The characteristic temperature $T_0$ is 185 °C. The slope efficiency is 450 and 800 mW/A at 300 and 80 K, respectively. In continuous wave operation, the output power is more than 150 mW at 80 K and 25 mW at 140 K. This high performance was achieved by improving the material growth and processing technology.