An electro-optic diffraction modulator/deflector using tota internal reflection and no external optics is described. The zero-order extinction voltage decreases, and the interorder angle increases, with decreasing interdigitated electrode pitch. With LiNbO3, all the zero-order energy is deflected by less than 60 V. The active-material volume is low, approximately 0.5 mm3. Further optimisation is possible.