Stable electro-optic striation grating produced by programed periodic modulation of the growth temperature

Electrically controlled Bragg gratings implemented by periodic striations that were produced during the crystal growth are demonstrated in potassium lithium tantalate niobate crystals. The striations were generated by blowing air with periodic flow at the flux surface. The gratings were investigated by measurements of the diffraction efficiency versus the applied electric field. It was found that the composition grating induced correlated gratings of the refractive index and the low frequency dielectric constant. The latter, under the application of a uniform electric field, produced an electrically controlled birefringence grating through the quadratic electro-optic effect.