Phase-locked high-peak-power sub-ns laser for electron modulation in quasi-steady-state microbunching

Steady-state microbunching (SSMB) represents an innovative light source concept capable of generating high-average-power, short-wavelength coherent radiation. To experimentally validate the quasi-SSMB, a turn-by-turn coherent modulation on electron bunches in a storage ring is critical. For this purpose, a dedicated phase-locked pulse laser system with high peak power and high repetition rate has been developed. Utilizing continuous-wave (CW) seed laser electro-optic gating in combination with a master oscillator power amplifier (MOPA) architecture, the laser system produces 1064 nm laser pulses with a pulse width of 0.5 ns, a repetition rate of 6.25 MHz, and a peak power of 32 kW. Based on an iodine frequency-stabilized CW seed laser as the frequency reference, an optical phase-locked loop (OPLL) achieves phase locking of the output pulse laser. Beat signal measurements demonstrate significant phase noise suppression in the 10 Hz-10 kHz range. This work proposes a method for achieving laser-based coherent modulation on electron bunch trains and demonstrates a versatile design scheme capable of generating phase-locked laser pulses with high repetition rate and high peak power.