Power electronic devices based on wide bandgap (WBG) semiconductors (like silicon carbide (SiC), gallium nitride (GaN), diamond (C) ...) offer better performances when compared to those based on silicon (Si). However, the periphery protection of these devices must be carefully designed to sustain high voltage bias. This paper shows how the OBIC (Optical Beam Induced Current) technique applied to WBG semiconductor devices could be useful to study the efficiency of different protection techniques. Firstly, a theoretical approach is given to present the method. Then, this electro-optical characterization technique is performed on high voltage power devices in a vacuum chamber allowing to study the spatial distribution of the electric field in the semiconductor. Results are mainly focused on SiC devices for the sake of availability. Finally, comparisons with Finite Elements Methods using TCAD tools are performed showing the local high electric field strength. This paper shows also additional results and measurements on GaN and diamond Schottky diodes. Finally, extraction of OBIC signals allows to know some physical features as shown in the last section like ionization coefficients, minority carrier lifetime and local defects in semiconductors.