Abstract

Low threshold microlasers require small gain volumes, high-Q optical modes and efficient matching of the mode volume to the gain volume. We can approach the ideal limit at mode volumes of only a fraction of a cubic wavelength by forming semiconductor microdisks surrounded by air or Sio₂. The whispering-gallery mode around the edge of the disk can then be used as the high-Q lasing mode. The gain near 1.5µm wavelength is provided by excitons in 100 Å thick InGaAs quantum wells separated by 50Å InGaAsP barriers with gap wavelengths near 1.1µm. The total thickness of this layered structure is 1150Å, approximately a quarter wavelength in the semiconductor. For this thickness the TE1 mode dominates the mode structure in the direction perpendicular to the plane of the disk. The whispering-gallery mode around the edge of the disk is strongly confined to the disk plane due to the large index of refraction ratio between the semiconductor and the surrounding dielectric.

© 1992 IQEC