Fiber-optic electro-optic sensors for non-destructive electron beam diagnostics

Non-destructive, least-invasive and precise characterization of the high-reputation rate and intense accelerated charge particle bunches has attracted tremendous interest due to their indispensable role in X-ray free electron laser (XFEL) and linear accelerators (LINAC) applications. Electro-optical sampling is a non-destructive technique to characterize charged particle beams in which the interaction between the generated electric field of charged particles and an electro-optic material is used to indirectly characterize the charged particle beam using an optical probe laser beam passing through the electro-optic material. Electro-optic detection has been commissioned for single-shot longitudinal single-shot electron bunch lengths measurements as well as single-shot electron beam arrival monitors (BAM). We propose an Electro-Optical (EO) electron beam position monitor (BPM). We Propose a novel fiber-coupled electro-optic BPM using dielectric microchip electro-optic electric field sensors for non-perturbative electron beam center of mass position measurements. The proposed approach and device can also measure electron beam pointing angle. Our electro-optical sampling technique employs thin film of lithium niobate instead of bulk ZnTe or GaP crystal used in state-of-the-art electro-optic electron beam characterization sensing systems. Using thin film lithium niobate leads to higher sensitivity compared to those two materials due to larger electro-optic coefficient. Furthermore, the utilization of optical fibers significantly simplifies the alignment of the optical probe beam and the device. In addition, thin film lithium niobate technology enables possibility of phase matching the THz signal and optical signal and hence achieving modulation speed close to THz range. In Phase I, we will design and fabricate a prototype electro-optic field sensors with unprecedented frequency bandwidth (> 1 THz) for the implementation of a fiber-coupled electro-optic BPM measuring the center-of-mass of pico- and sub picosecond electron pulses. We will also develop a measurement system for the BPM at accelerators. The performance of these BPM sensors will be characterized in both the laboratory and an accelerator environment. The developed electric field sensor based on this SBIR proposal can be used in many different applications. Many applications are looking for low cost, compact and robust electric filed sensors. Among these applications are near field vectoral electric field measurements for electromagnetic compatibility, antenna field characterization, plasma processing equipment.