Effects of Thin Film Multi Layers Thickness and Refractive Index on Narrowband Filters Transmission's

Abstract

AbstractBoth thickness and refractive index of a multi-layered membrane have a greateffect on getting a narrow pulse width. So choosing the coating material should beregarded with accuracy of refractive index. The thickness of multilayer of coatinghas an important effect on type of multilayered coating material and at the end hasa great role on cost control.In this paper we will get analysis and design of different kinds of filters namedband-pass filter, by choosing materials for different coating to have less possiblenarrow pulse width. The 1st design is TiO2/SiO2, 2nd design In GaAs/SiO2 and3rd design is GaAs/SiO2, each of these designs consists of a number of layers (31)are presented respectively. These designs consist of two materials high/low indexwith wavelength range from (750-1100) nm and the design wavelength is (900)nm.From this study we get the effect of thickness and refractive index by havingthe transmission characteristics curve versus wavelength for any type of dielectricsthin film of multilayered membrane. At the end we get optimal design for a narrowlaser pulse width.