The problem of enhancing the sensitivity of a measurement transducer of high-frequency external electric fields is examined. It is shown that solving this problem is possible by using a ring waveguide with two horizontal or vertical slots filled with an electro-optic polymer. The structure of a measurement transducer of a ring waveguide with two horizontal or vertical slots is examined. In waveguides with two slots, a greater intensity of optical radiation in the region of the slots is achieved, in comparison with waveguides with one slot. The values of the optimal distances between the slots and their width for maximum sensitivity of the measurement transducer are determined. As a result of using the active organic compound SEO125 and waveguides with two slots, the transducer under study makes it possible to measure the strength of alternating electric fields of frequency 0–10 GHz over the range 150–16·106 V/m with resolution up to 150 V/m. The measurement transducer can be used to detect high frequency waves and electromagnetic pulses, as well as to analyze external electromagnetic interference and diagnose high frequency electronic circuits.