Interfacial roughness and temperature dependence of narrow band thin film filters for the DWDM passive optical networks

Abstract

In the design of new components for passive optical networks (PONs), the non-ideal properties are worth considering. In this paper the influence of interface roughness and temperature changes on final transmittance of downstream channels blocking filters for next generation dense wavelength division multiplexing passive optical networks(DWDM-PONs) is shown. The transmittance as the filter transfer characteristicswas calculated with the transfer matrix method. The roughness was expressed by root mean square deviations from an ideally smooth surface and was taken into account in the modified Fresnel coefficients. It is demonstrated how the interfacial roughness may increase the insertion loss and decrease the channel bandwidth which results in reduction of transmitted light energy through the filter.