Electro-optical probe dedicated to the on-line testing of electronic systems

The measurement of electrical quantities, like voltage or current, using optical methods is a domain in full expansion. In this paper, we present preliminary results of a simple design EO probe. It is made of PZT material comprises between two electrodes that also act as optical mirrors. The upper electrode is a semi-transparent gold layer, 50 nm thick, while the second is made of Pt. Numerical simulations show that a variation up to 7.2 % (0 to 5V) can be reached at normal incidence with such a structure with an upper mirror made of 2-quarter wavelength thin layers of Si/SiO₂. This present structure is used to characterize different composition of PZT in order to obtain the best EO coefficient. It is also used to discriminate between EO of the 1st or second order and also mechanical effects (piezoelectric effect).