Electrically Controlled Reflection Band and Tunable Defect Modes in One-Dimensional Photonic Crystal by Using Potassium Titanyl Phosphate (KTP) Crystal

摘要

The present paper describes the theoretical investigation and study of electrically controlled reflection band or photonic band gap (PBG) based on one-dimensional (1D) photonic crystal (PC) by using potassium titanyl phosphate KTP crystal. The proposed PC structure is composed of alternate layers of two materials in which one of the layers is KTP material. We use KTP crystal as one of the constituents layers because it is an electro-optical material and its refractive index changes with the change in the electric field intensity. Due to change in the refractive index contrast the range of reflection band or photonic band gap (PBG) of the PC structure changes. The reflectance/transmittance spectrum of the proposed structure is obtained by employing the transfer matrix method (TMM). From the analysis of reflectance curve it is observed that photonic band gap can be increased or decreased by applying the suitable value of the electric field intensity to the KTP crystal without changing the other parameters. Further it has been observed that reflection band of PC structure completely vanishes at a particular value of electric field intensity. In other study we use KTP crystal as a defect layer in normal PC structure, and found that the defect mode or transmission mode obtained in the band gap region varies with the change in the electric field intensity. Such type of PC structure can be used for the design of optical limiters, tunable optical reflectors and tunable wavelength selective filters.