Operating Characteristics of an Optical Filter with a Linearly Periodic Refractive Index Pattern in the Filter Material

A design for the fabrication of an IR filter by using a linearly periodic refractive index pattern on the macroscopic scale in a suitable material has been proposed. To predict allowed and forbidden bands of wavelengths for the lower modes, a mathematical analysis is presented. Numerical estimates of allowed and forbidden bands are also made. Several parameters controlling the range of operation and region of allowed wavelength bands have been identified. It is being suggested that the technical knowhow used in the manufacturing of optical fibres and integrated optical devices can successfully be employed for the fabrication of these filters.