High efficiency vertical-cavity lasers using low-optical loss intra-cavity dielectric apertures.

摘要

This dissertation leads to a greater understanding of vertical cavity laser (VCL) size scaling issues and performance limitations imposed by optical scattering loss, current leakage losses, and heating. This understanding is gained through a correlation of several different VCL measurements and device modeling, resulting in the identification of the key parameters to address in future structures.; The first measurements presented deconvolute the size dependent optical scattering losses and current leakage losses by measuring the differential efficiency as a function of size for etched-post and dielectrically apertured VCLs. These measurements show conclusively that the reduced optical scattering loss in dielectrically apertured lasers resulted in a dramatic improvement in device scaleability, efficiency, and threshold currents. This understanding led to the use of thin dielectric apertures to lower optical losses further, producing 2 {dollar}mu{dollar}m diameter VCLs that show only a 15% drop in differential efficiency compared to larger devices. With the losses measured, the currents lost to leakage around the active area, diffusion of carriers out of the active region, and non-radiative recombination were measured, showing that current spreading is the largest source of current loss.; Microwave measurements were also done on the low optical loss VCLs, showing the scaleability of the modulation frequency obtained through reduced optical scattering losses. A state-of-the-art 15.3 GHz at only 2.1 mA of drive current was measured. The saturation of the bandwidth at higher currents led to modeling of the effects of heating on the VCL performance. The modeling verifies the saturation of the bandwidth and points to the necessity of further reducing optical and carrier losses, but especially of eliminating unwanted series resistance if the ultimate bandwidth and efficiency performance is to be reached.