Researcher works at the HiRES apparatus.

Researcher aligns the fiber laser for the high-repetition-rate ultrafast electron diffraction experiment.

The stability of accelerators is primarily determined by the stability of the electromagnetic fields that accelerate and guide the beam. Berkeley Lab has become a center of excellence in low-level RF controls. Building upon success with the Spallation Neutron Source linac at Oak Ridge and then the FERMI@Elettra free-electron laser, we are now leading a multi-lab effort on this aspect of the  Linac Coherent Light Source-II project and looking forward to contributing to PIP-II, with its superconducting linac.

Another challenge is the synchronization of accelerators and lasers, which are used in many applications throughout modern accelerator complexes. We have applied our RF control approach to stabilizing mode-locked laser oscillators, a critical technique for various accelerator applications, such as photocathode RF guns, laser-based beam diagnostics, and staged laser-plasma acceleration.

An area of particular expertise is high-precision fiber-optic distributed timing and synchronization across wide areas. Berkeley Lab brought unique innovations and a high degree of development to this concept. Its femtoseconds-across-kilometers capability has proved especially useful to the Linac Coherent Light Source and LCLS-II.

A spinoff of our expertise is being developed: the use of field-programmable gate arrays to read the outputs of microwave-sensed outputs in quantum computing.

Laser Design and Control

Four scientists gowned and goggled for a laser area work at an optical table.

Our researchers are collaboratively developing a way to coherently combine many laser beams to achieve high peak power in an ultrafast pulse train that also has high average power.

Novel paradigms in which lasers impart acceleration potentials hold great promise for making accelerators much more compact. The next step, kBELLA, calls for significant improvement in the drive lasers’ peak power, average power, and pulse rate.

BACI and collaborators, including the University of Michigan and Lawrence Livermore National Laboratory, are working on a highly promising set of approaches that combines the output of many fiber lasers coherently so that the result is like a rapid train of single high-power laser pulses. We intend to integrate coherent beam combining with other methods of amplifying ultrashort pulses.