A novel design of nano layered optical fllter using photonic band gap materials

Abstract

Much interest has been drawn in Photonic crystal, which are novel nanostructure of light. In the present paper, we present how the emerging technology of Photonic crystal can be suitably exploited to design and make a nano sized tunable optical filter. A novel theory to design tunable optical filter using one -dimensional nano photonic structure is proposed in this present paper for ultraviolet and visible region ofwavelength. A periodic structure ofdifferent dielectric and semiconductor materials (i.e. air and GaAs, air and Ge) are used. This idea is based on the Kronig -Penny model in the band theory of solids. A detail mathematical analysis is proposed to predict the allowed and forbidden bands of wavelength with variation of angle of incidence and lattice parameter. It is possible to desired range of electromagnetic spectrum filtered with structure by changing the incidence angle of light and/ or changing the lattice parameter. The proposed filter structure can act as narrow band wavelength selector and wide band selector in the same region. The properties of the filter structure depend on the thickness of the two alternate regions for the selected materials. The proposed nano layered tunable optical filter may be suitably exploited in recent integrated optics, WDM technology, space technology, Acousto-optic tunable filter, communication, medical etc.