Coherent beam combination system and control method thereof

Abstract

The coherent beam recombination system provides an output recombined beam and comprises: a laser source providing a source beam with linewidth; a beam broadener providing a broadened beam from the source beam; a splitter splitting the broadened beam into a plurality of secondary beams; a plurality of channels coupled to the splitter. Each channel receives a respective secondary beam and provides a respective intermediate beam. Each channel has an optical amplifier, a phase modulator, an optical delay line, and an opto-mechanical element. The CBC system further comprises an optical sensor that provides a detection signal indicative of an intensity of a received optical beam; a focusing optics that receives the intermediate beams, provides the output recombined beam from a first portion of each intermediate beam, and provides a sampled recombined beam to the optical sensor from a second portion of each intermediate beam. The CBC system further comprises a control unit coupled to the optical sensor and the plurality of channels. The control unit comprises a phase-locking module configured to: provide a plurality of phase control signals to the phase modulators; receive the detection signal from the optical sensor, indicative of an intensity of the sampled recombined beam; calculate a cost function from the detection signal, wherein the cost function is a function of the intensity of the sampled recombined beam; perform an optimization algorithm of the cost function, configured to maximise the intensity of the sample recombined beam; and provide a plurality of updated phase control signals, based on a result of the optimization algorithm.