Space-variant partially polarized thermal emission is investigated. We show that by coupling surface phonon-polaritons to a propagating field, large anisotropy of the emissivity is obtained within a narrow spectral range. We experimentally demonstrate this effect by fabricating a space-variant subwavelength grating on a SiO2 substrate to encrypt an image in the polarization state of a thermal radiation field.
© 2005 Optical Society of America
Nir Dahan, Avi Niv, Gabriel Biener, Vladimir Kleiner, and Erez Hasman, "Thermal image encryption obtained with a SiO2 space-variant subwavelength grating supporting surface phonon-polaritons," Opt. Lett. 30, 3195-3197 (2005)