Laser diodes with highly strained InGaAs MQWs and very narrow vertical far fields

Abstract

The effect of variation of the number of highly strained InGaAs quantum wells embedded in GaAs layers on the crystal quality of the epitaxial layers and AlGaAs/GaAs laser diodes was investigated. With four quantum wells and very thick waveguide layers, reasonable efficient laser diodes emitting above 1100 nm with a narrow vertical far field (FWHM = 15 °) were obtained. Broad area laser diodes with 200 µm stripe width and an optimised doping profile emit nearly 20 W cw output power.

Feedback controlled growth of strain-balanced InGaAs multiple quantum wells in metal-organic vapour phase epitaxy using anin situcurvature sensor

“…InGaAs QWs are used as an active material in highpower laser diodes in the wavelength range between 870 nm and 1200 nm [1]. Output powers of nearly 20 W from 200 µm single emitter stripes have been demonstrated at 1120 nm [2]. Due to the larger lattice constant of InGaAs as compared to the GaAs substrate, with increasing indium content an increasing amount of stress is incorporated in the layer structure.…”

“…Therefore, using InGaAs QWs the maximum reachable wavelength lies around 1240 nm at a low growth temperature of 510 • C [3]. For lasers with multiple InGaAs QWs, high output powers and a good reliability can be best reached by using GaAs/GaAsP/GaAs barriers instead of GaAs barriers, because this strain compensation reduces the tendency to defect formation [2].…”