Integrated optical E-field probes with segmented modulator electrodes

Integrated optical E-field sensors using a Ti:LiNbO/sub 3/ Mach-Zehnder interferometer with a combined antenna and modulator electrode structure yielding a small size (12/spl times/3/spl times/2 mm/sup 3/ or 30/spl times/3/spl times/2 mm/sup 3/ for higher sensitivity, respectively) are presented. Segmented electrodes are used, yielding a sensitivity improvement of 10-20 dB compared to conventional electrodes, reduced signal fluctuations due to changing dielectric properties of the surrounding material and less field distortions. The experimentally obtained frequency response of our devices is flat up to f/spl ap/3 GHz. At 1 mW optical input power a sensitivity limit of E/sub min/=1 mV/m at 1 Hz bandwidth has been measured. Using a transparent ITO (indium-tin oxide) electrode without a SiO/sub 2/-buffer layer and with an additionally evaporated 100 nm-layer of amorphous Si, we have obtained a thermal stabilization of the field probes.>