Optimal measurement and phase conjugation algorithms used in the case of a priori indeterminacy of the statistics of the received signal

An analysis is made of the task of measuring and phase conjugation of the optical field against the background of noise in the case of a priori indeterminacy of the statistical properties of the received signal. Mode expansion of a useful signal is employed to show that the optimal algorithm may be realized in at least two variants: either on the basis of multichannel heterodyne reception and phase conjugation of the filtered signal at a radio frequency or with the aid of "physical" phase conjugation methods directly at an optical frequency. Expressions are obtained for estimating the quality of the measurements and phase conjugation. It is shown that practical realization of the latter variant of the optimal algorithm may result in a significant deterioration of the potential characteristics.