Operational characteristics and grating tuning of quantum well heterostructure lasers
Hall, Douglas Carleton
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Permalink
https://hdl.handle.net/2142/21410
Description
Title
Operational characteristics and grating tuning of quantum well heterostructure lasers
Author(s)
Hall, Douglas Carleton
Issue Date
1991
Doctoral Committee Chair(s)
Holonyak, Nick, Jr.
Department of Study
Electrical and Computer Engineering
Discipline
Electrical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Electronics and Electrical
Physics, Electricity and Magnetism
Physics, Condensed Matter
Language
eng
Abstract
Data are presented on Al$\sb{\rm y}$Ga$\sb{\rm 1-y}$As-GaAs-In$\sb{\rm x}$Ga$\sb{\rm 1-x}$As quantum well heterostructure diode lasers showing that the large band filling range of a combined GaAs-In$\sb{\rm x}$Ga$\sb{\rm 1-x}$As quantum well makes possible a very large tuning range in external grating cavity operation. The bandfilling and gain profile are shown to be continuous from the In$\sb{\rm x}$Ga$\sb{\rm 1-x}$As quantum well (L$\sb{\rm z}\sim 125$ A, x $\sim 0.2)$ up into the surrounding GaAs quantum well (L$\sb{\rm z}\sim$ 430 A). Continuous (cw) 300 K tunable laser operation in the 8700-9700 A range ($\Delta\lambda\sim$ 1000 A, $\Delta$h$\nu\sim$ 150 meV) and pulsed tunable operation in the 8450-9750 A range ($\Delta\lambda\sim$ 1300 A, $\Delta$h$\nu\sim$ 200 meV) is demonstrated. The prospects for developing a high-power, broadly tunable, long-wavelength diode laser source are also discussed.
"Other data are presented on the operational and thermal characteristics of Al$\sb{\rm x}$Ga$\sb{\rm 1-x}$As-GaAs quantum well heterostructure diode lasers grown on Si substrates. It is shown experimentally that ""junction-up"" operation (for diodes mounted with the junction side away from the heat sink and thus with the heat dissipated through the substrate) is enhanced for lasers on Si substrates. The higher thermal conductivity of Si reduces the measured thermal impedance of GaAs-on-Si lasers by $\sim$40% compared to lasers on GaAs. Continuous 300 K operation for over 10 h is demonstrated for a junction-up GaAs-on-Si diode laser. The effects of naturally occurring microcracks on the optical and electrical properties and operational stability of these devices are discussed. Data are presented showing cw 300 K operation for over 17 h for a GaAs-on-Si diode laser with stress-relieving microcracks running parallel to and inside the active laser stripe. The maximum cw 300 K output power for these devices ($\sim$30 mW/facet) is shown to be limited by catastrophic facet degradation rather than accelerated optical degradation of the crystal at higher power levels."
The low-temperature (77-200K) cw operational characteristics of these cw 300 K GaAs-on-Si QWH diode lasers are also examined. Operation is demonstrated for over 500 h with a junction temperature as high as $\sim$200 K for a diode previously operated cw 300 K for over 10 h with its junction side mounted away from the heat sink. The data indicate that cw 300 K lifetimes longer than the previously demonstrated 17 h may be possible. The effects of the optical power level on the degradation rate are examined.
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