Room-temperature continuous-wave external cavity interband cascade laser tunable from 3.2 to 3.6 µm.

We report on wide tuning of external cavity interband cascade lasers (EC-ICLs) in continuous-wave operation at room temperature. The antireflection coated ICL gain chips were tuned with a diffraction grating in the Littrow configuration. A tuning range of 313 cm (360 nm) from 2789 cm to 3102 cm (3.22 to 3.58 µm) in continuous wave at 293 K was demonstrated with a 5 µm-wide, 1.5 mm-long gain chip. A maximum output power of 13 mW and a minimum threshold current of 62 mA were measured at the peak gain. The heat dissipation of the chip was 0.2 W at threshold and 0.8 W at the maximum current of 200 mA.