Resonant modes and laser spectrum of microdisk lasers

New semiconductor microdisk and microcylinder resonant cavities have been studied with measured lasing emission wavelength at l51550 nm, l5980 nm, and l5510 nm. Position in a cylinder is specified by natural axial coordinate z, radial coordinate r, and azimuthal angle u. Isolated short cylinders are disks of thickness L. The design and optimization of a semiconductor microdisk laser is critically dependent on the Q of resonant optical modes as well as the spectral and spatial overlap of these modes with the active medium. Microdisk lasers typically consist of a quantum well active region which can exhibit optical gain at, for example, l51550 nm. For such devices disk radius 0.5 mm,R,10 mm and thickness 0.05 mm,L,0.3 mm. Because of high optical confinement due to the air/semiconductor interface, in essence device models involve solving for the optical field c(r ,u) in the two-dimensional transverse direction for a medium with refractive index n5neff . The Helmholtz equation for optical field is separable in r and u so that c(r ,u)5R(r)e and we may write