Photon and Phonon Science for Energy Technologies
Photons and phonons are two of the fundamental carriers of thermal energy in and between materials. At the quantum scale, they behave as waves: photons are waves of electromagnetic fields, while phonons are waves of oscillatory atomic vibrational energy. When you get enough of them all together, they act like particles and give rise to the more familiar macroscopic phenomena of heat conduction and thermal radiation. By leveraging a fundamental understanding of the behavior of photons and phonons from the nano-scale up, we are developing technologies that can transport energy and convert it from one form into another with new levels of control and efficiency.
Projects
In collaboration with Stanford, we are developing a novel and cost-effective process for creating advanced thermoelectric (TE) materials constructed from silicon nanowire (Si-nw) arrays, and demonstrate with a prototype device, its performance and ability to scale to mass production for heat-to-electricity conversion. Constructing TE materials from Si-nw arrays increases operating temperature (up to 800°C) and allows them to be implemented where the heat-to-electricity conversion efficiency is high. Additionally, implementing Si-nw will create a cost-effective TE waste heat recovery system (TE‑WHR) capable of achieving a heat-to-electricity conversion efficiency >10% (~2.5 times more than market TE). These improvements will attract a large variety of industries, including petroleum refining, geothermal power, maritime and automotive, and enable access to multi-billion dollar global markets. This project is in collaboration with Stanford University and is funded by the California Energy Commission (CEC).
Thermal noise plagues the coherence times of qubits, limiting the scalability of quantum computers. On the other hand, ultrasensitive detectors such as for individual particle scattering events fight to efficiently capture what little thermal signals are generated. In both cases, being able to manipulate and control phonons could lead to significant technological advancements. We are working on using the latest nanoscale design methods to directly control phonon transport. This project is funded by the Laboratory Directed Research and Development Program (LDRD).
Thermal drying processes in the manufacturing sector constitute ~7% of US primary energy consumption, and mostly rely on fossil fuels for energy. The overarching goal of this project is to use infrared (IR) heating to improve their energy efficiency, reduce greenhouse gas emissions, increase manufacturing drying speeds, and simultaneously improve the quality of the dried products. IR thermal drying has the potential to greatly improve energy efficiency over conventional drying methods, but the state-of-the-art technologies are limited by lack of control of the IR photon spectrum emitted by the heating elements. In the visible spectrum this lack of control gives rise to large energy losses and degraded product quality. 
In this work we are developing multilayer photonic structures (photonic filters) for potential wide-ranging applications in the areas of industrial heating and drying. The photonic filters primarily emit in the desired spectral range as demanded by the need of the process, while recycling less optimal photons. This project is funded by the Laboratory Directed Research and Development Program (LDRD).