Modeling of surface-emitting grating-outcoupled lasers for mid/far-infrared difference-frequency generation

Physical principles and an analytical theory of operation of the hybrid-emitting nonlinear-mixing lasers which are dual-wavelength near-infrared or mid-infrared lasers simultaneously generating mid/far-infrared difference-frequency radiation due to an intracavity mode mixing are developed. In the hybrid-emitting design, the difference-frequency mid/far-infrared signal is surface-emitted by means of a grating, while the dual-wavelength near-infrared or mid-infrared lasing proceeds in a standard edge-emitting geometry. Employing intracavity optical pump fields provides the possibility of the injection current pumping and removes many problems associated with the external optical pump, e.g., drive absorption and spatial inhomogeneity which were encountered in previous works on nonlinear optics in semiconductors. The grating (dielectric or metal) can be implemented either on the surface or in the bulk of any nonlinear-mixing laser, independently on its electrical pumping design, and provides an efficient diffractive (Bragg) coupling of the nonlinear current, generated in the bulk of the heterostructure, to the output mid/far-infrared radiation in the free space