Study of Electron Relaxation Processes in Intersubband Laser Heterostructures
Final progress rept. 14 Jul 2000-13 Apr 2004
STATE UNIV OF NEW YORK AT STONY BROOK RESEARCH FOUNDATION
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Comprehensive experimental and theoretical study of the electron relaxation processes responsible for the depopulation of the lower lasing slates in intersubband and interhand laser heterostructures has been accomplished. In theory, LO-phonon assisted relaxation has been given special attention due to the high impact on the laser gain and temperature performance. We showed that in type-II laser heterostructures LO phonon assisted depopulation of the lower lasing slates is more efficient than corresponding interband tunneling process. We suggested type-II intersubband laser design with phonon-assisted depopulation and lower lasing level located near the upper edge of the heterostructure leaky window, where direct interband tunneling depopulation is inefficient. This design is beneficial for the laser performance providing the highest value of the matrix element for intrawell optical lasing transition and simultaneously preventing thermal backfilling of the lower lasing states. We also proposed a piezo-acoustic DFB QCL tunable in a wide wavelength range, which is especially important for spectroscopic applications of the quantum cascade lasers. Experimental program was focused on the study of temperature dependence of the optical gain and loss which is the most important factors for laser high-temperature operation. Special measurement technique has been developed for MIR type-II lasers which allows gain and loss spectra analysis in wide temperature range. Heat removal and hole leakage processes were also studied using MQW InP-based laser and laser array heterostructures.
- Electrical and Electronic Equipment
- Lasers and Masers
- Quantum Theory and Relativity