LARGE ELECTROOPTIC MODULATION EFFECT OBSERVED IN ION-EXCHANGED KTIOPO4 WAVE-GUIDES

We report the observation of an anomalously large electro-optic modula tion effect: in potassium titanyl phosphate (KTiOPO4) waveguides fabri cated under various conditions. An interferometric method was used to measure the effective electro-optic coefficient in the waveguides by m easuring the phase retardation of an optical mode when-a voltage was a pplied across the substrate, We observed thai at low modulation freque ncy the effective electro-optic coefficient In the waveguides can be h igher than the bulk value bf a factor up to about 100. A space charge model relating the mobile charge, space charge field, and observed enh ancement in the electro-optic modulation is proposed to explain the me chanism of this effect. Calculation for dc steady state, small signal analysis, and large signal simulation is compared to the experimental observation. Possible device application and long term effects on syst em operation are also discussed. (C) 1996 American Institute of Physic s.