Steady-State and Transient Characteristics of Microcavity Surface-Emitting Laserswith Compressively Strained Quantum-Well Active Regions

摘要

In conventional semiconductor lasers, the dimensions of the optical cavitygreatly exceed the photon wavelength, and the photon density of states forms a continuum since it is essentially that of a bulk system. On the other hand, in an ideal laser, one would like to have a single optical mode coincident with the maximum in the gain spectrum of the active medium. We show that substantial density of states quantization and enhancement of the fraction of photons spontaneously emitted into the lasing mode can be obtained by reducing the lateral width of the surface emitting laser. For emission at lambda = 0.954 microns, the threshold current density can be drastically reduced by increasing the coupling factor to a few percent. For a cavity structure width of 0.3 microns, the threshold current density is 50 A/cm2, compared with 250 A/cm2 for the 0.6 microns cavity. At lower still lateral widths, the cavity loses its vertical character, and confinement of the lateral optical mode rapidly deteriorates.