Recent progress in manipulation of photons by photonic crystals — Thermal emission control for sensors & energy harvesting

Converting a broad-band into a narrow-band thermal emission spectrum with minimal loss of energy is important for efficient environmental sensors and biosensors as well as thermo-photovoltaic power generation systems for energy harvesting. Here I will discuss such thermal emission control by manipulating photonic modes with photonic crystals and material absorption with quantum-well intersubband transitions. We show that the emission peak intensity for our device can be more than 4 times greater than that of a blackbody sample under the same input power and thermal management conditions, where the emission bandwidth and angular spread have been narrowed by 30 and 8 times, respectively. These results indicate that the energy saved by thermal emission control can be recycled and concentrated to enhance the narrow peak emission intensity. In the presentation, I will also describe other recent progresses in photonic crystals including high-Q nanocavity-based new phenomena, on-demand 3D optical guiding, etc.