A novel waveguide filter for reducing crosstalk in optical cross connection and switching in all-optical networks

A novel filter structure is presented in this paper to reduce the crosstalk in cross connection and switching in all-optical networks based on dense w avelength-division multiplexing (DWDM). Following the principle of an optic al film filter, the filter is constructed by a dielectric waveguide with th e waveguide boundary or the waveguide itself discontinuous in the transmitt ing direction. As the propagation phase constant beta does not change in th e wave propagating direction z, the waveguide system can be considered as a homogeneous dielectric medium with effective refractive index n(e) in this direction. Because the effective refractive index ne changes with the thic kness or parameters as ni of the waveguide at a given field mode, we arrang e different ne alternately as an optical film filter. After proving this ki nd of waveguide's filtering properties, the design principle and an example are given, which will be very useful to reduce the crosstalk in optical cr oss connection and switching in all-optical networks based on DWDM. This ki nd of filter can be easily connected to other related components. (C) 2000 John Wiley & Sons, Inc.