Room-Temperature Operation of Discrete-Mode InGaAs–AlAsSb Quantum-Cascade Laser With Emission at $\lambda=3.3\ \mu$m

Discrete-mode quantum-cascade lasers have been developed in the InGaAs-AlAsSb-InP materials system. For an uncoated 10-μ m-wide ridge waveguide and 3000-μm-long cavity, the laser had a threshold current density J
_th
of 4.2 kA·cm
^-2
(I
_th
=1.5 A) at 300 K with a slope efficiency of 80 mW/A. A stable single-mode emission near 3.3 μ m with a sidemode suppression ratio of nearly 25 dB was observed and a tuning coefficient of 0.22 nm/K was obtained in the temperature range of 253 K <; T <; 303 K.