Vahideh Khadem Hosseini Ghasemi - Department of Electrical Engineering, , High Education College , Islamic Azad University Boushehr Branch,Boushehr, Iran
Mohammad Orvatinia - Telecommunication College /Ministry Information and communication Technology(I.C.T),Tehran, Iran
Asghar Ebrahimi - Malek Ashtar University of Technology,Tehran,Iran

In this paper a new type of cavity filter is investigated. The device is based on a Fabry–Perot interferometer which employing a cavity and two dielectric Bragg mirrors. The cavityfilter uses multi layers of ( 2 SiO ) and (ZnS) to produce a multi - layers ZnS/ 2 SiO cavity filter operating in the center wavelengthof 1550 (nm). Zinc sulfide is used in this paper due to its high refractive index, while 2 SiO due to its low refractive index material. The filter is to be coated on Fused Silica having the index of 1.55 and operates at normal incidence. The ZnS/ 2 SiO thin film structure was designed using the Thin Film Design software (TF Calc). The simulation results show that the transmittance of the ZnS/ 2 SiO filter is about 95% for centralwavelength of 1550 nm. This filter is essential for monitoring and reconfiguring optical networks

Multiple cavity filter, optical communication,thin film layer