High average power fiber laser system with high-speed, parallel wavefront sensor

Abstract

A high average power fiber-laser system comprises a master oscillator for generating a primary laser signal; a beam splitter array for splitting the primary laser signal into N secondary laser signals; an optical frequency shifter for shifting the frequency of the primary laser signal; a phase modulator array for providing phase compensation of the N secondary laser signals; N single-mode dual clad fiber amplifiers for amplifying the N secondary laser signals and generating an output beam; a beam sampler for sampling the wavefront of the output beam, defining an array of sampled signals; means responsive to the array of sampled signals for interferometrically combining the array of said sampled signals and the shifted primary laser signal into an array of heterodyne optical signals, each having a phase that corresponds to the state of phase of the array of sampled signals; and means responsive to the array of heterodyne optical signals for providing a plurality of feedback signals to the phase modulator array that are linearly proportioned to the state of phase over at least one wave to provide phase compensation of the secondary laser signals. This includes digital dividers for dividing electrical signals by a selected integer and an exclusive OR gate for providing a pulse train having a duty cycle that reflects the phase to be compensated.