Date of Award
Master of Science in Electrical and Computer Engineering (MSECE)
Electrical and Computer Engineering
Committee Member 1
Timothy S. Fisher
Committee Member 2
Daniel S. Elliott
Modern electronics are increasingly more capable of high-power density operation, which presents important thermal challenges. High-power laser diode bars have proliferated in recent years, and while they can generate high optical powers, slope efficiencies are theoretically limited, resulting in high excess heat loads and consequent temperature shifts that can impair many applications. As a result, managing the ensuing heat flux and temperature changes has become increasingly important. Although traditional single-phase cooling solutions are limited by their convection coefficient to a certain temperature difference, two-phase solutions have potential for significantly higher convective coefficients. Flash boiling is a cooling method that can facilitate high levels of transient convective heat transfer, while allowing active control of coolant temperature. The transient nature of a flash cooling event is compatible with the heat load generated during operation of a high-power laser diode bar. Here, optical properties including spectral shift, spectral broadening, optical power, and beam quality are characterized over time. System inputs and outputs are correlated and evaluated via a statistical surrogate model. In certain cases, flash boiling is demonstrated to be a viable means of regulating laser diode bar temperature to achieve desirable optical output characteristics.
In parallel, GaN HEMTs have seen rapid adoption in electronics applications due to their capability to operate at high powers at quick switching rates. As power levels rise, thermal management becomes crucial to avoid long-term degradation of the device. Spatial thermal modeling can help improve long-term reliability by linking local temperatures with various temperature dependent failure mechanisms such as hot-carrier injection.
Schlenker, Evan L., "Modeling and Characterization of High-Power Electronic Devices: System Analysis of Laser Diodes with Flash Boiling and GaN HEMT Reliability Modeling" (2018). Open Access Theses. 1590.