Measurement of the vortex spectrum in a vortex-beam array without cuts and gluing of the wavefront

We presented a new method for measuring the squares of the amplitudes and phases of partial vortex-beams in a complex beam array in real time. The method is based on measuring the high-order intensity moments and analyzing the solutions of a system of linear equations. Calibration measurements have shown that the measurement error at least for an array of 10-15 beams does not exceed 4%. When measuring beams with different fractional topological charge of optical vortices, we revealed a sharp decrease in the OAM for small deviations of the topological charge from the integer order which is associated with a sharp increase in the number of integer-order vortices. The application of this approach e.g. for the terabit-information processing in optical fibers provides significant advantages in comparison with the traditional diffraction methods and opens up additional possibilities of information compressor when modulating not only the OAM but also phases of partial beams.