Abstract

Strong optical confinement in InGaAsP/InGaAs layered quantum-well microdisks is obtained due to the large refractive index contrast between the semiconductor (n=3.5) and the low-index air or SiO₂ surrounding the semiconductor disk. The 5 and 10μ diameter microdisks are 500 to 1500Å thick, less than a half wavelength in the semiconductor. Whispering-gallery optical modes traveling around the microdisk edge have high Q values and only one of these modes is dominant within the photoluminescent spectral region for the InGaAs quantum well gain medium. Optically pumped microdisks lased at 1.3 to 1.5μm wavelengths when the substrate temperature was in the 77 to 270°K range. Thresholds as low as 50μW have been measured for CW pumping and substrate temperatures near 77°K. These microlasers have potential for thresholds near a microwatt if the pumped carriers are confined to the very small volume of the whispering-gallery mode. The disks are formed by selective etching of MOCVD-grown InGaAsP/InGaAs on InP substrates, resulting in a thin disk supported by an InP pedestal. High efficiency coupling of the laser field into thin optical waveguides should be possible by positioning the waveguide in the evanescent region surrounding the disks.

© 1991 Optical Society of America