35GHz tunable planar Bragg grating using liquid crystal and electric field

We present the first experimental demonstration of an electrically tunable, first order Bragg grating using liquid crystals. Similar devices have been modelled in the past but not experimentally realised. Using direct UV writing, a waveguide and Bragg grating are simultaneously defined in a planar silica on silicon substrate. Replacement of the overcladding with liquid crystal in the vicinity of the grating allows the electro-optic properties of the liquid crystal to be exploited. Interactions of the evanescent field with the variable refractive index of the liquid crystal allow the centre wavelength of the filter response to be tuned