Some properties of extremely restricted thermal radiation beams

Abstract

Physical peculiarities of the equilibrium thermal radiation have been considered within the black body model for the case of ultimate restrained photon flows inside an ideal ("lossless") optical communication channel. Restrictions connected with the uncertainty relations have been used to determine critical interrelations between the thermal radiation parameters, sizes of thermal radiator and ideal photodetector. The effects conditioned by the "cutting" of the thermal radiation mode number in a small-size (but not quantum-size) radiator have been included into consideration. Spectral efficiency has been analysed in terms of the amount of information contents in spatially restricted beams of thermal radiation.