High energy laser processing system

A high energy laser processing system comprising:

• an optical source configured to provide a continuous wave, cw, initial laser signal having a spectral linewidth in the range 15 to 250 GHz;
• an optical modulator having a cw operating mode in which it is configured to transmit the cw initial laser signal unmodulated and having a pulsed operating mode in which it is configured to apply amplitude modulation to form a pulsed initial laser signal of initial laser pulses;
• an optical splitter configured to power split the initial laser signal into a plurality of seed laser signals;
• a plurality of optical amplifiers configured to amplify the seed laser signals to average optical powers in the range 800 W to 5 kW;
• a plurality of phase actuators configurable to adjust phases of seed laser signals, the phase actuators provided between the optical splitter and respective optical amplifiers;
• an optical beam combiner configured to receive seed laser signals from the optical amplifiers and configured to combine cw seed laser signals into a cw combined laser signal and to combine pulsed seed laser signals into a pulsed combined laser signal;
• phase control apparatus configured to determine phase differences between seed laser signals within a said combined laser signal and operative to transmit phase control signals to phase actuators, the phase control signals configured to cause phase actuators to adjust phases of seed laser signals to minimize phase differences between seed laser signals within a said combined laser signal;
• and
• a controller operative to transmit at least one control signal configured to cause the optical modulator to switch between operating in the pulsed operating mode and operating in the cw operating mode.