Amplitude spatial filtering in the processing of signals from a single-fiber multimode interferometer

An investigation was made of the characteristics of the processing of signals from a single-fiber multimode interferometer by the amplitude spatial filtering method. The power of the radiation transmitted by an amplitude spatial filter was found to be directly proportional to the correlation coefficient of the distribution of the intensities in the interference signals during the stage of forming of the filter and during processing. The correlation coefficient was governed by an additional average difference between the phases of the modes in the interferometer. The linear relationship between the radiation power at the exit from the amplitude spatial filter and the correlation coefficient of the intensities was retained for any form of the functional dependence of the transmission of the filter material.