FIELD: fiber-optical systems. SUBSTANCE: optical communication element with variable mode includes first optical fiber which core gradually thermally swells to change mode of transmitted light, second optical fiber which core gradually thermally swells to change mode of transmitted light, element of increased thickness made of rubber treated with ultraviolet rays is placed between first and second optical fibers. Sections of ends of element of increased thickness match sections of corresponding ends of first and second swelled optical fibers after exposure and treatment with ultraviolet rays. Each end grows thicker within limits of specified value. Element of increased thickness maintains constant dimensions within limits of distance between swelled parts of first and second optical fibers specified in advance. Element of increased thickness is positioned in element letting channel pass and has two ends to which correspondingly first and second optical fibers are connected. Element letting channel pass has coat intended to fill it up with rubber treated with ultraviolet rays, to level first and second optical fibers and to prevent leak of rubber from element letting channel pass. According to another variant element of increased thickness is Y-shaped. EFFECT: reduced optical losses. 17 cl, 6 dwg
