ELECTROOPTICAL EFFECT OF BI4GE3O-12 CRYSTALS FOR OPTICAL VOLTAGE SENSORS

The electro-optical coefficient r41 of Bi4Ge3O12, corresponding to the sensitivity of the optical voltage sensor, and the temperature depend ence of response characteristics to applied step voltage are studied. From these measurements, two kinds of dc drift are found to exist in B i4Ge3O12 crystals. One is found to be due to the relaxation of the pie zoelectric polarization (type (a)), and the other is explained as the deduction phenomenon by the thermally induced space-charge field (type (b)). By correcting for dc drift of type (a), the accurate value of r 41 = 1.09 X 10(-12) M/V is obtained at 855 nm wavelength.