Characteristics of fused long wavelength InGaAsP/AlGaAs air-gap VCSEL structures

Summary form given. We study long wavelength fused InGaAsP-AlGaAs air-gap VCSEL structures which are obtained in-situ by the localised wafer fusion technique. We have used InGaAsP/InP active cavity material and undoped AlGaAs/GaAs DBRs, all grown by MOCVD at 650/spl deg/C. InGaAsP/InP material is grown with a constant group V elements composition throughout the structure. It includes a strain compensated quantum well structure with 1% compressive strain in the wells and 0.8% tensile strain in the barriers. The peak of the photoluminescence spectrum is at 1550 nm. Air gap was formed by etching a 80 /spl mu/m diameter recess in the active material before fusion. Cavity mode of the resulting VCSEL structure is well centered in the stopband of the DBR. Pulsed and CW single mode emission with more than 30 dB side mode suppression ratio were obtained under optical pumping using standard laser diodes at 980 nm. The threshold optical pumping power of 3 mW was typical for the devices used in this study. Cavity mode wavelength of the air-gap structure at 1521 nm was measured below and above laser threshold. Cavity mode at 1523 nm both below and above threshold was measured when air gap was field up with acetone. Due to rapid evaporation of acetone cavity mode shifts back to 1521 nm in 3-5 min. Experimental results with VCSEL structures having different air gap geometry and using various liquids to fill them up are presented as well.