Abstract

Recently, we have proposed^[1-3] and demonstrated^[4] a new type of mid-IR quantum cascade (QC) lasers based on interband transitions in type-I quantum wells. This interband cascade (IC) laser takes advantage of the broken-gap band alignment in the InAs/Ga(In)Sb heterostructure to recycle electrons from the valence band back to the conduction band, thus enabling sequential photon emission from active regions stacked in series. However, by sticking to the interband transitions, it circumvented the fast phonon scattering which limits the performance of devices based on intersubband transitions such as the QC lasers based on InGaAs/InAlAs quantum wells (QWs). In addition to realizing stimulated emission at wavelengths around 3 and 4 μm,^[4-6] room temperature electroluminescence has also been observed at wavelengths up to 15 μm.^[7] In comparison, the QC lasers based on intersubband transitions have been successfully demonstrated to operate at wavelengths from 4.3 to 11 μm.

© 1998 Optical Society of America