Patent ID: 8014430

Claim:
A quantum cascade laser utilizing non-resonant extraction design, the quantum cascade laser comprising: (a) a semiconductor with only one type of carrier, the carrier being electrons, the semiconductor having multiple layers of In x Ga 1-x As/Al y In 1-y As/InP and having at least twenty gain stages, each gain stage comprising multiple In x Ga 1-x As layers having a thickness between about 1 to 5 nanometers and multiple Al y In 1-y As layers having a thickness between about 1 to 5 nanometers, being quantum wells and barriers, respectively, the semiconductor having an active region and an energy relaxation region, the active region having at least lour quantum well/barrier pairs; (b) an electric current injected along an x-axis perpendicular to the multiple layers; (c) an insulator to confine the electric current under a contact stripe and to prevent the electric current from spreading in a y-axis parallel to the multiple layers; (d) at least two final levels, denoted here as levels 1 and 1 ′, for a transition down from a level 2 , levels 1 and 1 ′ being spaced at about 18 meV, a carrier wave function for level 1 overlapping with a carrier wave function for level 2 , a carrier wave function for level 1 ′ overlapping with a carrier wave function for level 2 ; (e) an energy spacing E 21 greater than E LO and being about 70 mcV; (f) an energy spacing E 31 of about 100 meV; (g) an energy spacing E 32 equal to E LO ; (h) a total optical power greater than 1.5 W at 300K; and (i) a wall plug efficiency greater than 8.5%.