ANTIRESONANT WAVE-GUIDE ADD/DROP FILTER USING FABRY-PEROT INTERFERENCE

We describe planar waveguide structures that accomplish the Fabry-Perot filtering functionality by using the wavelength selective coupling between antiresonant optical waveguides. By using different cladding layer thicknesses wavelength selectivity is achieved despite the fact that the coupled waveguides have equal core thicknesses, in contrast with filters based on conventional waveguides. For the polymer-based configuration investigated here a resolution of 1.2 nm was obtained with a free spectral range of 12 nm. We also describe a dual output filter which could drop or add two different wavelengths at once in a wavelength division multiplexing (WDM) system.