Transmission enhancement using a negative-refraction layer

Materials with a negative refractive index have some unique properties and may be used to enhance photon tunneling through a distance comparable to tire wavelength. This study describes the transmission of electromagnetic waves through a four-layer structure, where the two end layers are semi-infinite dielectrics with the same refractive index (n(1) = n(4) > 1) the 2nd layer is a vacuum gap (n(2) = 1) of width d(2), and the 3rd layer is made of a material whose refractive index is negative (n(3) < 0) for the wavelength of interest. The effects of layer widths and the value Of n(3) on the tunneling transmittance are investigated. The calculation results show that the insert of a negative-refraction layer can increase the hemispherical transmittance, suggesting that materials with negative refractive indexes may be used to construct microscale energy conversion devices.