Basic Researches on Active Optical Resonators of Multi-Quantum-Well Structure to be Used for Direct Microwave Modulation

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[1] Rediative recombination coefficient of free carriers in multi-quantum-wells. The radiative recombination coefficient B of two-dimensional free carriers in a selectively doped GaAs/n-AlGaAs quantum well was determined by measuring the decay time of photoluminescence from the wells. The experimental findings are well explained by the theory of band-to-band recombination of two-dimensional carriers.[2] Absolute flatness of GaAs-AlGaAs quantum wells. It is found that the interfaces of AlGaAs-on-GaAs formed by continuous MBE have the roughness of an atomic layer height whose step interval is 200A, resulting in the photoluminescence(PL) broadening. It is also found that this roughness is smoothed by growth interruption for tens of seconds prior the formation of the interfaces, leading to a drastic sharpening of PL spectra.[3] Splitting of photoluminescence spectra and negative differential resistance caused by the electric field in multi-quantum-well structure. It is found that when the … More perpendicular electric field exceeds a critical value, the field induces a resonant coupling of the two lowest quantum levels in the adjacent wells, resulting in splitting of photoluminescence spectra and in negative differential resistance of the photocurrent.[4] Energy levels and electron wave functions in semiconductor quantumwells having superlattice-alloylike material as barrier layers. Energy levels and wave functions are studied in GaAs quantum wells for the case when barriers are formed with ultra-short-period superlattice. The modified Kronig-Penney analysis is found effective in predicting the observed energy and has clarified a feature of enhanced penetration of wave function into the barrier layers.[5] Active optical resonator with a very short cavity length. Active optical resonators, which have active layers of GaAs-AlGaAs superlattice and multi-layered optical reflectors having low refractive index material of GaAs-AlAs superlattice of a very short period, were experimentally studied. It was found that the mode-coupling and the mode-competition are the basic phenomena in understanding the behaviors of these resonators. Less