Patent ID: 8937277
Filing Date: 2015-01-20
Classification: G02B

Abstract:
1. A single-frequency optical filter comprising elements with a negative electric permittivity, and especially reflectors, formed on a surface of a dielectric support layer and defining at least one periodic grating of parallel through slits, the periodicity, the height, and the width of the slits being selected to that said slit grating forms a wavelength-selective structure for a wavelength ranging within a predetermined wavelength range: wherein the thickness and the refractive index of the support layer are selected so that said layer forms a halfwave plate for a wavelength from said predetermined range of wavelengths; wherein the filter further comprises, in contact with the surface of the support layer opposite to that having the slit grating formed thereon, a medium having a refractive index smaller than that of the support layer to obtain a resonant guided mode in the support layer; wherein the period of the or of each of the slit gratings ranges between approximately and approximately where λ is a wavelength from the predetermined range of wavelengths and n1 is the refractive index of the support layer; and wherein the refractive indexes of the support layer and of the medium satisfy the relation where n1 is the index of the support layer, and n2 is the index of the medium.