Author : Timothy M. Calvert
Publisher :
ISBN 13 :
Total Pages : 197 pages
Book Rating : 4.:/5 (795 download)
Book Synopsis Development of Visible Vertical Cavity Surface Emitting Lasers by : Timothy M. Calvert
Download or read book Development of Visible Vertical Cavity Surface Emitting Lasers written by Timothy M. Calvert and published by . This book was released on 2001 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: As coaxial cable networks rapidly approach their data carrying limit an alternative method of data solution to this problem is needed to cope with the demand for high data rates. A low cost solution to this problem is to transmit data in parallel via cheap multimode plastic fibre ribbons and to use monolithic arrays of red VCSELs as the optical transmitters. VCSELs' intrinsic high speed, planar geometry and circular beam profile make them ideally suited for such systems. Other commercial applications include bar code readers, laser printing, visible displays (such as head up displays) and the automotive and aerospace industry. Visible VCSELs suffer from excess heating due to several factors. In particular the top p-doped A1GaAs distributed Bragg reflector (DBR) mirror presents a high series resistance due to the large valance band offset leading to strong Ohmic heating and poor thermal impedance. This situation is amplified by the stipulation that the VCSEL is bonded down with the p-doped mirror uppermost, which further increases the thermal impedance of the packaged laser.To overcome these problems this work considers methods of extracting the heat generated internally by examining different fabrication schemes. By means of a thermal model developed, the optimum fabrication parameters with regard to mesa diameter and substrate thickness that provide the most efficient heat extraction from the devices are determined. The use of substrate etch back and wafer-bonding techniques will allow the VCSEL to be processed on alternative substrates such as Si which will improve the device heat sinking due to silicon's good thermal conductivity. In addition, the ability to fabricate VCSELs on Si increases the feasibility of integration with Si CMOS electronics.This work has produced devices emitting at 668 nm (20°C) with record heat sink temperature operation up to 80°C and over 1 mW single mode output power at 20°C. Devices emitting at 665 nm and 675 nm have been fabricated, producing multimode output powers at 20°C of 2 mW and 2.8 mW respectively. Bondable VCSELs have been successfully transferred to non GaAs substrates with no deterioration of performance. A six-element array operating at 675 nm capable of being butt coupled to 125 ~m diameter fibre has produced over 12 mW output power at 20°C with no evidence of thermal cross talk between elements in the array.
