Thermal Radiative Properties of Photonic Crystals

We investigate the spectral directional reflectivity of photonic crystals assembled with 2μm silica particles. The propagation of electromagnetic wave can be controlled by photonic crystals. Therefore photonic crystals are anticipated for advanced control of thermal radiation beyond solid state properties. Samples are prepared by Catalysts & Chemicals Industries Co., Ltd. The close-packed photonic crystals are fabricated on a Si wafer by using self-assembly of the colloidal particles under the specific condition. We measure reflectivities of the samples by using a FT-IR (Fourier Transform – Infrared Spectroscopy). The spectral reflectivity is enhanced at specific wavenumber. The peaks of spectral reflectivity shift to larger wavenumber as a function of an increased incident angle. The angular dependency of reflectivity can be roughly explained by using the modified Bragg’s equation taking into account Snell’s law. We show that the reflectivity in IR range is well enhanced by using a photonic crystal.   This paper was also originally published as part of the Proceedings of the ASME 2005 Heat Transfer Summer Conference.