Methods of Signals Theory in the Problems of Optical Radiation Description

On the critical evaluation basis of the signals theory it is shown that it is necessary to develop its physical aspect, based on the quantum ideas. Within the framework of the quantum approach, where the energy of radiation changes over time in jump, the existence of frequency-temporal duality of photons is shown and the absence of operator connection between the time and frequency characteristics of the optical signal. The instantaneous power of the optical signal is described by a sequence of delta functions, similar to the sampled signal in the communication theory. Methods of communication theory and properties of photon spin allowed to make the transition to the classical approximation of the optical signal.