Abstract

Quantum cascade lasers (QCL) are fundamentally new in that: (1) their wavelength can be tailored over a wide range (so far from 3.4 mm to 20 mm) using the same combination of materials by a suitable choice of the active layer thicknesses (a few nm), (2) their optical power is greatly enhanced by the cascade effect (one injected electron creates 25-75 photons in traversing the active region). These devices invented at Bell Labs in 1994, now outperform all other mid-ir semiconductor lasers in peak and cw optical power (0.5 W at 300 K and 0.2 W at 80 K with maximum operating temperatures of 175 K, in pulsed and cw mode respectively), and single mode tunability with >30 dB side mode suppression ratio( up 150 nm).1,2

© 2000 IEEE