Investigations of Quantum Dot Lasers
Abstract
A detailed theoretical and experimental study of the application of quantum dot active regions to edge-emitting lasers and electro-optic modulators was undertaken. The theoretical work included calculation of the bandstructure and electronic properties of self-assembled quantum dots, carrier scattering rates and the oscillator strength and gain of interband and intersubband transitions. Experimental work included growth of self-organized dots and active devices, their fabrication and characterization. Very narrow PL linewidths in the dots were achieved (approx. 19 meV) by the incorporation of buried stressor dots. The dynamics of hot carriers and carrier relaxation rates were characterized by differential transmission spectroscopy. It was established from a variety of measurements and calculations that electron-hole scattering is the dominant carrier relaxation mechanism in quantum dots. Modulation bandwidth measurements on QD lasers at cryogenic temperatures (f-3dB approx. 30 GHz at T = 100K) confirmed the role of electron-hole scattering. The electron-optic coefficients of quantum dots was measured for the first time and a QD modulator has been demonstrated. Bistability and gain switching has also been observed and characterized. The unique carrier dynamics in quantum dots is favorable for the realization of intersubband emitters and detectors, and these have been investigated.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 15, 2000
- Accession Number
- ADA379134
Entities
People
- Pallab K. Bhattacharya
Organizations
- University of Michigan