Date of Award

12-1997

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Engineering Physics

First Advisor

Craig Largent, PhD

Abstract

Recombination mechanisms in mid-IR semiconductor lasers are strongly dependent on the carrier density of the active region. The objective of this research is to improve previous carrier density estimates through the incorporation of spectral information. One hundred photoluminescence (PL) spectra were calculated for a variety of carrier densities. Calculations were made for an InAsSb/InAlAsSb multiple quantum well laser sample assuming parabolic bands. The widths of the calculated spectral profiles were tabulated as a function of carrier density. Actual spectra were measured using the Ultrafast Mid-Infrared Photoluminescence System, which uses upconversion to measure the PL intensity in time steps smaller than 1 ps. PL spectra were obtained at 30 times, ranging from 100 ps to 3 ns. Spectral widths were measured and tabulated as a function of time. Combining the plot of calculated spectral width vs. carrier density with the plot of measured spectral width vs. time, we were able to describe the variation of carrier density with time. The carrier density vs. time plot thus generated agreed with earlier measurements by Cooley for low carrier densities. The discrepancy at higher carrier densities could be due to changing experimental conditions or the break down of the parabolic band approximation.

AFIT Designator

AFIT-GAP-ENP-97D-04

DTIC Accession Number

ADA339045

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