Abstract

Optical filters capable of dropping and adding signals at specific wavelengths into an optical fiber with minimum perturbations are essential components in WDM optical ring networks.^1,2 Such filters usually consist of a 1 × N demultiplexer followed by an N × 1 multiplexer. The first element demultiplexes the frequency components of the input WDM signal into N waveguide ports. A desired frequency signal is dropped by connecting the corresponding port to a fiber. The second filter element remultiplexes the remaining N – 1 frequency components into the fiber output. A signal at the same frequency as that of the dropped component can be added to the filter output by the unused port of the multiplexer (note that the add/drop functionality can be applied to more than one frequency component). The frequency-reuse capability of this type of filter is an essential feature for maximizing the performance of a WDM optical ring network.

© 1995 Optical Society of America