Continous wave operation of interband cascade lasers based on type-II InAs/
Ga(In)Sb heterostructures is reported. The interband cascade lasers, consis
ting of 23 cascaded active regions, lased at wavelengths near 4 mu m. conti
nuous wave operation was observed from 60-110 mu m wide by 1.02 mm long mes
a-stripe lasers at temperatures up to 70 K.