Injectorless quantum-cascade lasers

An “injectorless” quantum-cascade (QC) laser is presented. The requirement of using injector regions to transport electrons from the lower laser level and other low-lying energy levels of one active region to the upper laser level of the next electron-downstream active region was eliminated by using an appropriately designed double-quantum-well “chirped” superlattice active region. The major advantage of the “injectorless” QC laser is the close packing of the active regions and the concomitant large optical confinement factor. Using a cascade of 75 consecutive active regions, designed for emission at λ=11.5 μm, a pulsed peak output power of 270 mW is achieved at 7 K and approximately 10 mW at the maximum operating temperature of 195 K.