Design of beam splitters for optical filter tapping elements

The design of metallic and dielectric beam splitters for optical fiber tapping elements is detailed. Discussion of metallic beam splitters includes formulas for calculating the beam splitter by the method of characteristic matrices noting that aluminum is favorable because it can be evaporated with an electron beam. Dielectric beam splitters, of which the most easily realized type is a periodic dielectric multilayer system are covered, with formulas for reflectance and transmittance given. As with metallic beam splitters, dielectric splitters show pronounced polarization effects which decrease as the number of layers is increased. It is concluded that dielectric beam splitters can also be designed for wavelength demultiplexing, for which applications shortwave-pass and longwave-pass edge filters are suitable.