Quantum parallel laser: a unipolar superlattice interminiband laser

Designs are given for parallel (rather than cascade) intersubband lasing in superlattice structures of group IV and III-V materials. Structures with population inversion due to coupled wells have minibandwidths too narrow for coherent transport and the incoherent interperiod rates are too small for population of a significant number of periods. A single-well period with local population inversion gives operation in the coherent regime. An example is given for the III-V materials. Both SiGe-Si and Si-ZnS are discussed for intersubband lasing at 1-20 μm.