Quantum-cascade lasers without injector regions operating above room temperature

We present above-room-temperature operation of an injectorless quantum-cascade (QC) laser. The active region is designed as a four-level staircase and has been realized in the strain-compensated material system Ga0.4 In0.6 As Al0.56 In0.44 As based on InP. In pulsed operation the lasers work up to a heat-sink temperature of 340 K, the highest temperature achieved so far with injectorless QC lasers. A large wavelength shift is observed for higher bias fields and (therefore) at high temperatures (10 μm at 77 K and 8.4 μm at 300 K).