Tunable Filter Waveguide Element

Application:  Tunable filters are used to route, switch and monitor signals in wavelength division multiplexed (WDM) telecommunications systems.  The challenge is to design filters that are both tunable over a broad wavelength spectrum and that preserve the integrity of the information on the optical carrier.  In the present application, a Bragg grating filter is holographically written into a thick waveguide, and then the waveguide is stretched and compressed to tune the filter wavelength.

Features:  Large diameter, fused silica single mode waveguides are centerless ground into “dog bone” shaped geometries to 2um tolerances.  The ends of the waveguide elements are diced and polished at 7 degrees to reduce back reflection and then plasma cleaned in preparation of final packaging.