Electrical and Computer Engineering

Dissertation Defense

High Fidelity Coherent Pulse Stacking Amplification with Intelligent System Controls

Hanzhang Pei

Emerging applications of laser plasma accelerators require next generation laser drivers with multi-kW average power and TW peak power. Our vision for delivering such performance is through the coherent spatial and temporal combining of femtosecond pulse fiber laser arrays. The time domain combining is implemented as coherent pulse stacking amplification (CPSA), where modulated pulses propagate through optical cavities to interfere and stack into a single pulse. This technique extends the energy scaling capabilities of chirped pulse amplification (CPA) by ~102.

This dissertation focuses on developing a high-precision CPSA system with high fidelity. Using FPGA-based control algorithms, stabilization of 81-pulse stacking with high efficiency and long-term stability was achieved for the first time; adaptive optimization of pulse modulation that improves stacking fidelity over time was demonstrated. High-precision stacking techniques were developed for reducing alignment and control errors to enable theoretically expected CPSA performance. Using CPSA, extraction of ~90% stored energy at >10mJ level from a single large-core Chirally-Coupled-Core (CCC) fiber was achieved, setting record performance for a single-channel femtosecond pulse energy. This opens pathway to a practical implementation of multi-J pulsed system and further intelligent control capabilities in the future.

Chair: Professor Almantas Galvanauskas