Short-Wavelength $(\lambda\approx 3.6\ \mu{\hbox {m}})$${\hbox {In}}_{0.73}{\hbox {Ga}}_{0.27}{\hbox {As–AlAs–InP}}$ Quantum-Cascade Laser

Abstract

We describe the design and implementation of a short-wavelength quantum-cascade laser emitting in the range of 3.6-3.7 mum at 77 K and in the range of 3.8-3.9 mum at 300 K. The shortest wavelength laser emission observed at 77 K is lambda=3.62 mum. The active region is based on the strain-compensated In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.73</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.27</sub> As-AlAs heterosystem on InP. The laser operates in pulsed mode up to 300 K, and in continuous-wave mode at 77 K. Laser threshold current densities are as low as 600 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 10 K, 800 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 77 K, and 3.8 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 300 K in pulsed mode. The temperature coefficient T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is as high as 143 K. Driven with 50% duty cycle at 77 K, lasers deliver up to 70 mW average power per facet and the differential quantum efficiency is as high as 14% per cascade