High Performance Characterization of Photocathode Excitation Pulses

The fundamental limiting factor limiting Free Electron Lasers brightness is the electron source, or photoinjector. One solution to improve brightness is to use specifically shaped ultraviolet pulses to excite the photocathode, improving the electron cloud shape injected into the accelerator. Ultraviolet spatio-temporal ultrafast pulse measurement is needed to develop these pulse shapes. In this SBIR/STTR, we will develop new methods for temporal and spatio-temporal measurement of ultraviolet ultrafast laser pulses to support the development of laser pumped ultra-bright electron sources. These techniques need to provide high fidelity measurements with high dynamic range and high spectral resolution to monitor and help design photocathode driving pulses. In Phase I, we demonstrated the feasibility of our proposed techniques for high spectral resolution and high dynamic range pulse measurement of deep-ultraviolet ultrafast laser pulses. We further demonstrated a combined spatio-temporal pulse electric field characterization in the near infrared that can be readily used in the ultraviolet. In Phase II, we will build and calibrate a prototype high fidelity, high dynamic range temporal pulse measurement system with ultra-fine spectral resolution. This device will be integrated into our spatio-temporal measurement to demonstrate full spatio-temporal pulse measurement for ultraviolet laser pulses. Our ultraviolet ultrafast laser pulse measurement technology will provide badly needed diagnostics in commercial markets. Deep ultraviolet ultrafast pulses are used in both scientific instruments and the semiconductor industry. This SBIR project will also develop new technologies for telecommunications applications.