Switchable Bragg grating devices for telecommunications applications

Digilens is developing a new class of optical components based on the combination of Electrically Switchable Bragg Grating (ESBG) and waveguide technology. One or more optical waveguides are formed on a substrate which is used as one wall of a cell filled with an ESBG. The ESBG layer forms part of the waveguide cladding, such that the grating can interact with the evanescent field of the light energy traveling in the waveguide. This device architecture has been used to make Electrical Variable Optical Attenuators with more than 50 db of controllable range, flat attenuation over the optical communications C band, fast (<100 msecond) switching speed, and encouragingly low polarization dependent loss. Initial results on a variable wavelength-selective filter are also reported.