Stefan Grötsch

61.3: LED Light Source for RPTV Applications

A newly LED light source inclusive primary optics was developed with brightness levels suitable for future RPTV devices. Discussed are the crucial components for the performance of this LED package as the underlying chip technology, the suitable package design and the fitting primary optics. Presented as well are the benefits of using a LED light source in RPTV application.

Modeling and Experimental Result Analysis for High Power VECSELs

We present a comparison of experimental and microscopically based model results for optically pumped vertical external cavity surface emitting semiconductor lasers. The quantum well gain model is based on a quantitative ab-initio approach that allows calculation of a complex material susceptibility dependence on the wavelength, carrier density and lattice temperature. The gain model is coupled to the macroscopic thermal transport, spatially resolved in both the radial and longitudinal directions, with temperature and carrier density dependent pump absorption. The radial distribution of the refractive index and gain due to temperature variation are computed. Thermal managment issues, highlighted by the experimental data, are discussed. Experimental results indicate a critical dependence of the input power, at which thermal roll-over occurs, on the thermal resistance of the device. This requires minimization of the substrate thickness and optimization of the design and placement of the heatsink. Dependence of the model results on the radiative and non-radiative carrier recombination lifetimes and cavity losses are evaluated.