Physics & Astronomy ETDs

Publication Date

7-9-2009

Abstract

Edge-emitting semiconductor lasers with self-assembled InAs quantum dot (QD) active regions have demonstrated excellent device performance, including low sensitivity to operating temperature and record-low thresholds. In this dissertation, the application of QDs in vertical-cavity lasers (VCLs) is investigated. QDs can reach an emission wavelength up to 1300 nm on GaAs substrate. Key design and device processing issues are discussed and vertical-cavity surface emitting lasers (VCSELs) with both optical and electrical excitation are fabricated. VCSEL diodes with distributed Bragg reflectors (DBRs) formed by selective wet oxidation of AlAs, as well as standard GaAs/AlGaAs mirrors were processed. The latter performed better due to an increased number of QD layers in the cavity. Continuous wave (CW) operation of InAs QD VCSEL diodes with 1 mW output power and threshold current densities below 500 Acm^−2 were achieved. Replacing one of the DBRs with an external spherical mirror, vertical-external cavity surface-emitting lasers (VECSELs) allow the lateral dimensions of the device active region to be increased significantly, yielding high output power while still retaining single mode operation. Pumped by widely available high power diode lasers, QD VECSELs with CW output powers close to 400 mW were demonstrated with threshold pump power densities below 1 kWcm^−2. Since the VECSEL cavity extends into free space, additional optical components can be integrated. By using a non-linear β-Barium Borate (BBO) inside the cavity, we were able to frequency-double the QD emission to produce visible red light, which could be utilized for the red channel of full-color laser projection applications. Despite suboptimal cavity design and minimal heatsinking, output powers over 10 mW at a wavelength of 630 nm were achieved.

Degree Name

Physics

Level of Degree

Doctoral

Department Name

Physics & Astronomy

First Committee Member (Chair)

Balakrishnan, Ganesh

Second Committee Member

Diels, Jean-Claude

Third Committee Member

Sheik-Bahae, Mansoor

Language

English

Keywords

Semiconductor lasers, Quantum dots, Indium arsenide.

Document Type

Dissertation

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