Problems of superradiant lasing in magnetized quantum wells: two-colour regime, inhomogeneous broadening, and VCSEL scheme
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We analyze superradiant lasing, i.e. superfluorescence (SF) under continuous pumping, due to collective interband recombination of electron-hole (eh) pairs in quantum wells (QWs) placed in a strong magnetic field oriented perpendicular to the well plane. In such semiconductor systems, cooperative radiation processes lead to generation of coherent femtosecond pulses and can be observed even at room temperature due to complete quantization of particle motion, high spectral density of carrier states, high spatial density of effective "cyclotron quantum dots", and partial suppression of intraband scattering. Our simulations based on the Maxwell-Bloch equations show that, in the case of two neighbouring transitions between electron and hole Landau levels connected by scattering, two-colour superradiant lasing of the corresponding pair of resonance modes is possible under cascade cw pumping. We investigate analytically and numerically threshold conditions for this two-colour lasing as well as for superradiant lasing modified by "discrete" inhomogeneous broadening due to fluctuations of the number of atomic layers in actual QW heterostructures. Also, we present an example of real design and discuss necessary conditions for a vertical cavity surface-emitting laser (VCSEL) to operate in the superradiant regime.
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Saratov Fall Meeting 2000: Laser Physics and Photonics; and Spectroscopy and Molecular Modeling
