METHOD OF INTERNAL FEEDBACK LOOP ARRANGEMENT FOR PHASE SYNCHRONIZATION OF FIBRE LASERS GRID IN SYSTEMS OF COHERENT ADDITION OF BEAMS AND DEVICE FOR IMPLEMENTATION THEREOF

摘要

FIELD: physics.;SUBSTANCE: invention relates to laser equipment. Method of internal feedback loop for phase synchronization of fibre lasers in systems of coherent addition of beams is realized by device containing narrow-band laser, generating coherent, linearly polarized Gaussian beam, fibre splitter dividing radiation into N channels associated with N optical phase-shifting elements which control the phase of the optical wave, depending on the value of the applied control voltage, N fibre amplifiers having fibre output into free space. N fibre outputs form equidistant array of divergent beams with Gaussian intensity distribution, each of which consists of central maximum, containing ~ 92 % power and peripheral part, having N collimating lenses output, forming synthesized aperture consisting of clusters, each of which comprises central collimating lens and 6 peripheral collimating lenses assembled into hexagonal grid, which form in each channel flat wave front and direct radiation of all channels in parallel to each other. Small fractions of peripheral parts of Gaussian beams are intercepted after collimation by parabolic axial mirrors located behind plane of input pupil of each three of adjacent collimating lenses located in tops of triangle, one of which is located on optical axis of central collimating lens. Reflected from each parabolic mirror fraction of peripheral parts of radiation of neighbouring Gaussian beams, passing through the hole in the centre of three collimating lenses, are focused in plane of small diaphragm of photodetector, where their interference takes place. Signal from the photodetector is transmitted to the control controller, which generates iterative stresses in accordance with the stochastic parallel gradient descent method to control the corresponding phase-shifting cells, while maintaining the maximum attainable signal amplitude from the photodetector, which corresponds to phase synchronization of the laser beams.;EFFECT: technical result consists in provision of possibility to obtain high power density in systems of coherent addition of beams.;9 cl, 2 dwg