Coherent Spatial and Temporal Combining of Femtosecond Fiber Lasers at the Storage Energy Limit Enabling High-Power Drivers of Laser Plasma Accelerators and Other Secondary Radiation Sources

Password: CPSA

The 38 years since the invention of chirped pulse amplification (CPA) have seen an impressive increase in focused laser intensities, from 10¹⁵ W/cm² in 1985 to approaching 10²³ W/cm² today. Focused laser pulses have been used to do laboratory astrophysics, accelerate particles, create ultrashort high-brightness x-rays, and more.  However, the underlying laser technology providing these high focused intensities cannot scale beyond 1 Hz pulse rates, severely limiting the applications of laser-matter interactions; next generation laser drivers will require high pulse energy (0.1-10J) at high repetition rates (10-100kHz) for practical use.

This talk will discuss my work on coherent spatial and temporal combination of fiber lasers for high energy, high repetition-rate laser sources. A record level of energy in a femtosecond pulse generated by a single fiber amplifier is enabled by coherent pulse stacking amplification (CPSA) along with careful control of accrued nonlinear phase. Energy is further increased through a coherent beam combining (CBC) array of four amplifiers integrated with CPSA, providing up to 25mJ, a record high energy from so few parallel spatial channels. As a first application experiment fast neutrons are generated in a free-flowing deuterated water target, a first from a fiber laser. The techniques developed in this work provide essential groundwork for future scaling of high-energy, high-power coherently combined laser systems.

Chair: Professor Almantas Galvanauskas