The internal electric field plays a fundamental role in radiation detectors and access to it is therefore strategic. An important and widely used material in room temperature detectors is CdTe. This semiconductor exhibits the electro-optical Pockels effect, which is the linear response of the refraction index to an applied electric field. This allows to probe the electric field distribution inside the detectors with good spatial and temporal resolution. In this talk I will show recent results related to optically induced electric field perturbations. Trap-related optical doping is demonstrated in Schottky devices. Original experimental approaches enable to highlight the local perturbation on the timescale of the charge carriers transit time. A 2D Electric field imaging on such a timescale together with the visualization of free carrier motion is in progress, which is expected to provide a deep insight into charge transport mechanisms. The underlying scope of the present talk is to point out how fixed and free charges, on their corresponding timescales, can be used to control the local electric field and the optical modulation. These are general concepts in semiconductors which, with suitable materials/design, can be exploited in optoelectronics. Speaker(s): , ADRIANO COLA Bldg: BOSSONE 302, DREXEL UNIVERSITY, Philadelphia, Pennsylvania, United States, Virtual: https://events.vtools.ieee.org/m/402114