Photonic Electric Field Sensing System (PEFS) is an instrument that optically measures the electric field. It integrates a fiber optic E-field sensor probe, a laser, photo-receiver, amplifier module, and associated electronics. The probe is made of entirely dielectric materials and connected to the system via fibers. The fiber optic E-field sensor system provides advanced attributes of very fast response, extremely high damage threshold exceeding 5MV/m, high fidelity with little disturbance to the E-field, and remote sensing capability. The sensor system covers a broad frequency range up to 18 GHz. The amplifier gains are adjustable to optimize the sensitivity and the dynamic ranges. The system is designed to connect to a spectrum analyzer to characterize the RF signal outputs.