Narrow-Band Thermal Radiation Based on Microcavity Resonant Effect

The microcavity resonant effect is used to realize narrow-band thermal radiation. Periodic circular aperture arrays with square lattice are patterned on Si substrates by using standard photolithographic techniques and reactive ion etching techniques. Ag films are deposited on the surface of Si substrates with aperture arrays to improve the infrared reflectance. On the basis of the micromachining process, an Ag/Si structured surface exhibiting narrow-band radiation and directivity insensitivity is presented. The emittance spectra exhibit several selective emittance bands attributed to the microcavity resonance effect. The dependence of emittance spectra on sizes and direction is also experimentally examined. The results indicate that the emittance peak of the Ag/Si structured surface can be modulated by tailoring the structural sizes. Moreover, the emittance peak is independent of the radiant angle, which is very important for designing high-performance thermal emitters.