Widely tunable high-power external cavity quantum cascade laser operating in continuous-wave at room temperature

A grating-coupled external cavity quantum cascade laser operating in continuous-wave at room temperature is reported. Single-frequency operation tunable over more than 160 cm−1 around the centre wavelength of 4.6 µm has been observed at a chip temperature of 300 K. The maximum optical power at the gain peak was 300 mW, corresponding to a wall-plug efficiency of 6%. Observed power output at the gain bandwidth edges was in excess of 125 mW.