Mid-infrared quantum cascade lasers

The achievement of laser action associated with intersubband transitions opens the door to a new class of infrared sources in a technologically important spectral region. Recently, we have demonstrated low temperature lasing action using a coupled-well structure with a graded-gap electron injector imbedded in a waveguide. In this work, we demonstrate high temperature (125K) operation of a similar GaInAs QW laser device.