Communications optiques par interférométrie à grande différence de marche en éclairement non parallèle

Abstract

A generalisation of an optical wave communication system is proposed in which a wide band light source is modulated interferometrically using a path difference longer than the coherence length (Delisle and Cielo). The behaviour of the double interferometer system is studied theoretically and experimentally for the case of a non-parallel light beam. It is concluded that results similar to those obtained previously are applicable if the changes in direction of the light rays going through both interferometers obey an expression which we derive in terms of the path difference, the angle of the ray, and the wavelength. That same relation is equally useful for determining permissible misalignment between the two interferometers as well as the degree of turbulence of the medium between the two interferometers. Finally, the restrictions imposed on the system when light is transmitted between the two interferometers by means of an optical fiber are established. [Journal translation]