GREENS-FUNCTIONS THEORY FOR SEMICONDUCTOR-QUANTUM-WELL LASER SPECTRA

A microscopic approach for the computation of semiconductor quantum we ll laser power spectra is presented. The theory is based on nonequilib rium Green's function techniques that allow for a consistent descripti on of the coupled photon and carrier system fully quantum mechanically . Many-body effects are included through vertex corrections beyond the random-phase approximation. Band structure engineering is incorporate d in the theory as dictated by the coupled band solutions of the Lutti nger Hamiltonian. The influence of the detailed cavity-mode structure is accounted for by the photon Green's function. The theory describes the interplay among the various many-body, quantum-confinement, and ba nd structure effects in the gain medium and its action as a laser cavi ty. Numerical results for the recombination rates, optical response, a nd laser output power spectra are presented for strained-layer and lat tice-matched III-V systems at quasiequilibrium with variable design an d material parameters and under different excitation conditions. Activ e optical switching is demonstrated in specially designed structures.