Wavelength-selective Beam Splitters with Minimum Polarizing Effects for Wavelength-division Multiplexing in Optical Communication Systems

Abstract

A new method of designing dielectric edge filters for wavelength-selective optical tapping elements based on the beam splitter concept relies on the analysis of the envelope of the reflectance for the beam components oscillating normal and parallel to the plane of incidence in the passband of the filter. Despite the 45° angle of incidence of the beam, the strong polarizing effects usually encountered are almost entirely avoided for the two wavelengths that are to be demultiplexed. A number of multilayer stack designs of the type S(H/2 L H/2) ^k S are described in which the ideal reflectance R_s = R_p = 0 is realized for the s and p components at the wavelength to be passed, while the desired value R_s≈R_p≈1 is realized for the wavelength to be rejected.