Distributed Bragg deflectors fabricated in sol-gel based waveguides

We report the fabrication and first demonstration of a grating-coupled waveguide device called a distributed Bragg deflector (DBD). The device consists of a grating imprinted on a channel waveguide, which is in turn, embedded in a planar guide. Light propagating in the channel waveguide is coupled to a well-collimated, planar waveguide-propagating beam at nominally a right angle to the channel. The precise angle of the planar waveguide beam (the diffracted beam) is determined by the Bragg condition for the incident wavelength. The diffracted beams complex amplitude profile can be controlled by adjusting properties of the grating. Our devices were designed for operation at around 1.55 μm. In accordance with theory, the DBDs diffraction efficiency exhibits a strong polarization dependence. Both 1- and 4-cm-long grating devices have been evaluated.