Abstract: The invention relates to an optical wavelength multiplexer-demultiplexer using optical fibers. For a bidirectional three-channel link with two go channels and one return channel the multiplexer-demultiplexer comprises a chamfered link fiber (30) provided with an interference filter (25) and optically coupled with three intermediate fibers (13, 14, 15). A first intermediate fiber (13) is chamfered and fitted with an interference filter (20) and has an optical axis which intersects the optical axis of the link fiber at a given angle (.theta.), while a second intermediate fiber (14) is coupled to the chamfered fiber, with the filter (20) providing multiplexing and demultiplexing between the two go channels. A third intermediate fiber (15 is applied to the cylindrical wall of the link fiber to receive or tansmit the return channel via the filter (25). The multiplexer-demultiplexer is applicable to optical fiber telecommunication systems.

Abstract: A device for distributing light energy comprises a chamfered inlet fiber (2) which is coupled to a plurality of outlet fibers (3) which are grouped together in a matrix. The coupling is performed by a diffraction grating (5) which is inclined relative to the chamfered inlet fiber at such an angle that the diffracted beam is a parallel beam, and the matrix of outlet fibers is disposed on the path of said outlet beam. Such a device is applicable to optical fiber distribution systems.

Abstract: The receiver of an optical-fiber transmission system comprises a device for restoring each digital signal comprising a first comparator comparing the level of the electric signal with a first reference level and generating a signal when the level of the electric signal is less than the reference level, a second comparator comparing the level of the electric signal with a second reference level and generating a signal when the level of the electric signal is greater than the reference level, and a summator summing the signals generated by the two comparators.