Fiber-Based Drive Lasers

The new superlattice photocathode, adapted by Jefferson Lab scientists for use in CEBAF,
allows the use of readily available, fiber-based drive lasers, which require significantly less maintenance than laser types previously used in CEBAF. Introduction of these new lasers has reduced photo-injector downtime by more than 50% (from 2% total downtime to less than 1%).

A fiber-based drive laser was constructed using a gain-switched diode seed laser and ErYb fiber amplifier. Light from these components is converted to the 780 nm wavelength needed for the superlattice photocathode using a non-linear frequency doubling process to obtain more than four times the power of previous drive lasers. 

The result of these improvements (superlattice photocathode and fiber-based drive laser) has been to produce a highly reliable photo-injector capable of routinely producing up to 200 µA of electrons with a polarization level of 85%.