FIELD: optical communication lines. SUBSTANCE: multiplexer incorporates two waveguide matrixes which include assemblage of waveguides and single central waveguide connected correspondingly to first and second flat-waveguide regions between which ordered waveguide lattice is positioned. Central waveguides have inputs formed in such place where light beam transmitted from ordered waveguide lattice to flatwaveguide region, on separation boundary between corresponding matrix and flatwaveguide region is fixed. Light beam multiplexed by wave length is transmitted or released through central waveguide. In addition to light waveguides central waveguide where light beam is transmitted or released is formed in such place that spectra of radiation outgoing from light waveguides are not subjected to any effect and consequently, separation and unification of light beam according to wave lengths is possible simultaneously in direction from one matrix of light waveguides to another matrix as well as in opposite direction. EFFECT: increased functional reliability of multiplexer. 5 cl, 6 dwg
