Electric field intensity distributions inside a LiNbO3 crystal with different interdigital electrode configurations

Abstract

The variations of the electric field intensity inside Z-cut and Y-cut LiNbO3 crystals with interdigital electrode structures are computed on the AC and DC modes. Experimental observations show that with an internal reflection modulator constructed from a Z-cut crystal, the voltage required for a given modulation is less when operated in the DC mode than when operated in the AC mode. The nature of the field intensity distribution, however, suggests that when the parallel transmission arrangement is used the reverse condition is achieved when the distance between the optical beam and the electrode plane is smaller than a quarter of the electrode pitch.