Narrowband 1.5-μm Bragg filter based on a polymer waveguide with a laser-written refractive-index grating

We report the fabrication of narrowband frequency-selective filters for the 1.5-μm telecom window, which include a single-mode polymer waveguide with a submicron Bragg grating inscribed by a helium-cadmium laser. The filters have a reflectance R > 98 % and a nearly rectangular reflection band with a bandwidth Δλ≈0.4nm. They can be used as components of optical multiplexers/demultiplexers for combining and separating signals in high-speed dense wavelength-division multiplexed optical fibre communication systems.