Long-wavelength optical transmission of extremely narrow slits via hybrid surface-plasmon and Fabry–Pérot modes

Abstract

We have verified that extraordinary transmission of long-wavelength light through extremely narrow slits in a thick metal film can be achieved by hybrid surface-plasmon and Fabry-Ṕrot modes. Transmittance of these ultranarrow slits, which have width and thickness of 0.56 μm and 100 μm, respectively, for a terahertz light with wavelength of 225 μm can be 2.1 × 10 8 times higher than that predicted by using classic theory. Furthermore, the corresponding ratio between transmission wavelength and slit width can be up to 400, which is over 60 times larger than that the conventional grating-based surface-plasmon modes can provide.