Using the coupled-mode method, the effects of propagation of laser radiation in a coupler of two parallel waveguide arrays are studied. It is shown that due to the composite spatial structures of each of the subsystems, the structure of the spatial distribution of radiation intensity in the subsystems is substantially complicated in the investigating system.  At present, much attention is paid to the study of linear and nonlinear optical effects in arrays of coupled fibers. These studies are carried out using the coupled mode method, taking into account the interaction of this fiber both with the nearest neighbors and with the more distant ones. These interactions lead to the appearance in the optical fiber system of transverse discrete diffraction. At high excitation levels, when non-linear effects enter the game, light can propagate along the waveguides in the form of discrete soliton pulses. In such systems, a number of interesting phenomena arise, in particular, Bloch oscillations, Zener tunneling, dynamic localization, etc. In Bloch oscillations in the arrays of waveguides, taking into account a linearly varying correction to the propagation constant, depending on the number of the optical fiber. The features of the propagation of light in planar semi-infinite arrays of waveguides with a variable coupling constant between waveguides were studied. It was predicted the possibility of creating Chebyshev's of the I and II kind, Laguerre's, Legendre's, Jacobi's, and Gegenbauer's arrays.  We present the main results of a theoretical study of the effects of light propagation in one such system, namely, in a directional coupler consisting of two parallel array of optical fibers, taking into account the interaction with nearest neighbors and a linear dependence of the propagation constant on the optical fiber number. The starting point of our consideration is the system of equations for the amplitudes of coupled modes of two parallel infinite optical fiber arrays:  (1) where - coupling constant of the optical fiber with its nearest neighbors, is the coordinate along the fiber, is the coupling constant between arrays, is the anharmonic correction to propagation constant in each of the arrays which determines the phase difference between the adjacent array optical waveguides, is the similar correction for anharmonism coupling between arrays, and are the normalized field amplitude propagating modes in the n-th waveguide. Let us first consider the simplest case, when there is no interaction with the optical fibers of the neighboring array . In this case, radiation does not flow into the fibers of the second array, and, consequently, . Light propagates only in the optical fibers of the first array. In this case, the pumping acts only on the end of the zero fiber of the first array. The spatial structure of the intensity of the field of the n-th waveguide periodically varies with the coordinate along the fiber axis (Fig. 1).  In conclusion, we note that the spatial distribution of the intensity of propagating radiation in two parallel optical fiber arrays is very complex in view of the fact that each of the subsystems is characterized by a complex spatial periodic structure. This circumstance can lead to the creation of new devices for controlling the light propagation.