Optimization Design of Band Pass Filter in The Infrared Region

In the present work theoretically optimization design of wide and narrow band pass filters have been suggested over the range (1300-1800 nm.) within infrared (IR) region to use in modern optical laser system. These design based on quarterwave stack, for the numerical calculation, we used glass as the substrate, Zinc sulfide (ZnS) as and Cryolite ( Na3AlF6) as high and low refractive index respectively. For the normal incidence at the wavelength design 1550 nm, the results shows that the transmittance for the suggested design, (A / (HL) (HH)(LH) L(HL) (HH)(LH) / S), was (99.18 ). Also the number of order and the effect of incidence angle were investigated. The results shows when the number of order increase, the transmittance increase and the full width at half maximum decreases, while when the angle of incidence increase the transmittance will decreases with shifting of wavelength design toward shorter wavelengths of electromagnetic spectrum.