Real-time measurement for the electro-optic coefficient of a poled-polymer film in ATR configuration

Abstract

A new method which bases on the attenuated total reflection (ATR) technique is developed to determine the electro-optic coefficient of a poled-polymer film. The proposed ATR arrangement consists of a coupling prism, and four film layers deposited directly onto the base of the prism in sequence. The four film layers are metal film (which serves as a top electrode), poled polymer film, buffer and base electrode, respectively. A convergent light beam covering a suitable angular range is incident onto the prism base to excite a guided wave mode and the reflected light beam is imaged by a CCD array. Then resonance angle of the guided wave mode can be determined from the position of the reflectance minimum. It is demonstrated that the applying electrical field will cause a minute change in the refractive index of a poled- polymer film, due to the Pockles effect, which will result in a shift of the resonance angle. In order to make the measurement more successful, computer image processing method and optical image spatial filter technology are used in our measurement.