Abstract: A hybrid spatial and wavelength selector for optical switching matrices includes a guide system defining paths between input ports receiving light waves having diverse wavelengths and at least one output port. Gates on the paths are each opened or closed so that the light waves reaching the output port via the gates which are open are selected according to the input ports which received them and according to their wavelength. The guide system is situated only between the optical gates and the output port and includes a wavelength separation system assigning some of the paths to the light waves according to their wavelength. The selector has applications in fiber optic telecommunication networks.

Abstract: A selection module receives an upstream multiplex and selectively diverts at least one channel of the multiplex to a drop port. A switching unit directs the channel concerned to an add port during certain periods in order to reinsert it into a downstream multiplex including at least one other channel of the upstream multiplex. An amplifier has sufficient gain to give rise to a circulating wave during the aforementioned periods in a closed loop including the two ports and the unit. This wave balances the downstream multiplex. Applications include fiber optic telecommunication networks.

Abstract: The apparatus comprises a polarization controller (FPC1) and a generator (DDG1) for generating a differential delay between two orthogonal polarization modes. The controller and the generator are interposed between the link fiber (LF) and the receiver terminal (RX). A servo-control unit (SCU1) measures the degree of polarization (PL) of the optical signal delivered by the differential delay generator, and it servo-controls the polarization controller (FPC1) in such a manner as to maximize the degree of polarization (PL). Application to long-haul optical transmission systems.

Abstract: In particular for selectively dropping and/or inserting channels of a wavelength division multiplex, while minimizing losses, the apparatus includes n stop filters and optical switching means provided with n+1 inlet ports of ranks 0 to n, and n+1 outlet ports of ranks 1 to n+1, as well as a set of waveguides making it possible to couple each outlet port selectively to one of said inlet ports of lower rank. Each filter is provided with first and second opposite ports coupled respectively to an associated outlet port and to an associated inlet port of the same rank. Application to optical transmission, in particular for performing routing operations.

Abstract: The invention concerns a system for compensating polarization dispersion of channels in a wavelength-division multiplex signal. In accordance with the invention, the system comprises a plurality of cascaded polarization control modules respectively associated with said channels and a common differential delay generator. Each polarization control module comprises a drop and insert multiplexer for extracting the signal from the associated channel from the input multiplex signal and inserting a modified channel supplied by a polarization controller. The system further comprises a control loop for controlling the polarization controllers in response to the optical properties of the channel signals at the output of the differential delay generator and obtaining a compensated multiplex signal.

Abstract: The invention relates to an optical transmission system comprising a transmission line which includes at least one optical fiber amplifier. According to the invention, a stabilized gain optical amplifier is coupled to the input of the line, said stabilized gain amplifier including a local oscillator suitable for emitting an auxiliary compensation wave at a wavelength .lambda.loc which lies in the gain band of each optical fiber amplifier of the line. Provision is also made to modulate the pumping current of said stabilized gain amplifier to convey service information. The invention is applicable to optical transmission.

Abstract: To perform selective dropping and adding of channels of wavelength multiplexes without interposing active elements in the main transmission path, the apparatus comprises add-and-drop modules, each of which includes at least one stop filter provided with two opposite ports. An optical switch provided with a drop outlet is provided with drop inlets and with add outlets associated with the modules, and respectively coupled to the opposite ports of the filters. For each module, the switch is organized for selectively coupling one of its drop inlets to one of its add outlets and/or to the drop outlet.