Charles Zhang, 2013, Electrical Engineering

Quantum Cascade (QC) lasers in sensor systems help us monitor the health of our environment through the detection of emissions that have optical spectra that are in the mid-infrared range. Because of the costly nature of the laser and the novelty of the approach, the laser is not widely used. For the laser to be more efficient, the thermal management and optical properties of waveguides need to be more closely examined. As an intern in Professor Claire Gmachl’s group in the Department of Electrical Engineering this summer, I helped to develop the models of the QC laser design on Comsol to unable the examination of the QC optical and thermal waveguide properties. We compared the differences in laser core temperature between dry etching and wet etching showing that a 1 µm shallow etch in dry etching is better by as much as 10 Kelvin than a 15 µm deep etch, and by only 1 Kelvin between a 1 µm shallow etch and a 15 µm deep etch in wet etching. In terms of a shallow etch, dry etching is better than wet etching by a several Kelvin. These comparisons are meant to determine which profile, wet or dry etched, has better thermal properties.