Abstract: The present invention relates generally to highly power-efficient quantum cascade sources, such as highly power-efficient quantum cascade lasers having ultra-strong coupling between injector and active regions which may be configured to provide broadband quantum cascade lasers.

Abstract: The present invention relates generally to highly power-efficient quantum cascade sources, such as highly power-efficient quantum cascade lasers having ultra-strong coupling between injector and active regions which may be configured to provide broadband quantum cascade lasers.

Abstract: A quantum cascade source, such as a QC laser, is provided comprising a plurality of repeat units each including an active region and an injector region. The active region includes at least two quantum wells that, in response to an applied electrical bias, provide a first, second, and third electron energy level, each resulting from a respective quantum well excited state. The first and second energy levels are configured so that an electron transition from the first energy level to the second energy level emits a photon of a selected wavelength. The second and third energy levels are configured so that an electron transition from the second energy level to the third energy level comprises a nonradiative transition to empty the second energy level sufficiently quickly to promote a population inversion between the first and second energy levels.