Broad tuning range, high power quantum cascade laser at λ ∼ 7.4 µm

In this article, we report a high power quantum cascade laser (QCL) at λ∼7.4 µm with a broad tuning range. By carefully designing and optimizing the active region and waveguide structure, a continuous-wave (CW) output power up to 1.36 W and 0.5 W is achieved at 293 K and 373 K which shows the excellent temperature stability. A high wall-plug efficiency (WPE) of 8% and 13.6% in CW and pulsed mode at 293 K are demonstrated. The laser shows a characteristic temperature T₀ of 224 K and T₁ of 381 K over a temperature range from 283 K to 373 K. In addition, a far field of pure zero order transverse mode and a fairly wide external cavity (EC) tuning range (280 cm^-1) from 6.54 µm to 8 µm are achieved in pulsed operation. In addition, an EC single mode output power of 226 mW is obtained under CW operation at 293K.