<title>Microdisk lasers</title>

Abstract

Thin dielectric disks fabricated from semiconductors or possibly organic materials serve as low-loss optical resonators. The disk thickness is typically only a third of an optical wavelength in the material. Whispering-gallery modes near the disk edge account for the low-loss resonator modes. Microdisk lasers based on this thin disk resonator have been demonstrated using the InGaAs/InGaAsP system at wavelengths from 1.6 to 1.0 micrometers and in the GaAs/AlGaAs system at wavelengths near 0.8 micrometers . The simplicity of the fabrication for these resonators make them attractive for a wide range of materials and wavelengths. Both optical and electrical pumping have been demonstrated with thresholds for pulsed operation at room temperature near 1 mA in the electrical case. Electrical pumping is accomplished with relatively low resistance posts located above and below the disk. The microdisk radii can be reduced to 1 micrometers while maintaining sufficiently low optical loss for laser operation. At these small dimensions there is only one low-loss mode within the luminescence spectrum and a large fraction of the spontaneous emission from the active region is emitted into this lasing mode. This results in novel threshold characteristics including a gradual increase in light output near threshold and large, power independent, laser linewidths. Various schemes for coupling the microdisk laser output into waveguides and optical fibers will be discussed along with possible applications of these microlasers in 2D arrays and photonic circuits.