The laser system for the ERL electron source at Cornell University

A master oscillator-power amplifier (MOPA) laser system has been developed to meet the requirements of the Cornell ERL high brightness electron photoinjector. The system is comprised of a Yb-fiber laser oscillator, a single-mode fiber pre-amplifier and a double-clad, large mode area fiber amplifier. The system provides 5 watts average infrared power in a train of 3-ps pulses at 50 MHz. These pulses are efficiently frequency-doubled to produce 2-ps pulses at 520 nm with more than 40 nJ energy per pulse. We demonstrate an efficient longitudinal pulse shaping technique that allows us to achieve 20- to 40-ps-long, nearly flat-top pulses with sharp rise and fall times. We characterize the noise properties of the fiber oscillator and discuss the route to upgrade the system to achieve 130-watt average infrared power and a repetition rate of 1.3 GHz.