A system for multiplexed transmission of different wavelengths of light comprises an array of at least two light sources whose images are formed on the end of an optical fibre. The images have displaced spectra so that a different part of the spectrum of each light source is imaged on to the end of the optical fibre and each part is transmitted by the optical fibre. The images themselves may be displaced by displacing the light sources. A number of such arrays having light sources with emission spectra centered on different wavelengths may be used to increase the number of multiplexed transmission channels.

A multichannel light switch including a cylindrical-shaped light-focusing transmission body having a length equal to an odd multiple of one quarter of the pitch of light beam undulation within the body and having a total reflection coating applied to one end face thereof, which is normal to the axis of the transmission body. A stationary optical fiber bundle is arranged opposite to the other end face of the transmission body and is in parallel to the axis thereof. For light-path switching between the optical fibers, the transmission body is adapted to be displaced in a radial direction or to be rotated in a plane normal to the axis thereof.

A light branching device includes a light-focusing transmission body having a refractive index which decreases in proportion to the square of the distance from the plane of its optical axis, and two end faces perpendicular to the optical axis and a substantial light path length equal to an integral multiple of approximately one-half of the pitch at which the light propagates. The ends of a plurality of optical fibers are disposed adjacent to the end faces so that light emanating from one of the optical fibers is dispersed primarily in a plane parallel with the optical axis plane and impinges upon the end of at least one of the other optical fibers for transmission therethrough.

A multi/demultiplexer is disclosed wherein the light-conducting fibers are cemented into a perforated plate made of a photolithographically etchable material, and their terminal faces are ground down and polished together with the surface of the perforated plate. To compensate for focusing differences, a plate of appropriately matched thickness is disposed between the transparent supporting block and the surface of the perforated plate.

A device for coupling a first optical signal of a first wavelength into a transmission glass-fiber and for coupling a second optical signal, which has a second wavelength which differs from the first wavelength, out of the fiber. The two signals travel in the transmission glass-fiber in opposite directions. The optical signals also travel in other, spatially separated glass fibers. The device includes an imaging device arranged between the transmission glass-fiber and the other glass fibers. In the pupil of the imaging device, a binary optical grating is disposed. Other glass fibers receive the second optical signals which have been diffracted into the diffractions orders of the grating. The grating is a phase grating and is arranged on an optical axis of the imaging device. It has a duty factor of at least substantially 1:1 as well as an optical path difference, H=(n-1)h, which is substantially and