Mode partition noise in an optical transmission link is described by an improved theory. Power fluctuations of discrete lines in the laser spectrum are transformed by fiber dispersion into fluctuations of shape and amplitude of received electrical pulses, resulting in increased bit error rate. This effect was measured in two different ways: First by measuring power fluctuations in single spectral lines separated by a monochromator, second by bit error rate measurements using a fiber with particularly high dispersion to enhance the effect. Results of both measurements are in good agreement.

The basic principle of that device consists in integrating an optronic diode into the plug of an electrical connector, tied to an optical cable. The use of an electrical connector allows easy handling and testing. For checking the optical parts, an exceptional access to the fiber/diode interface is possible with the help of a special tool. EOCs are now beeing industrialized.

For the french CATV project, cost and reliability criteria have brought us to study and to choice technologies of connectors, splices mechanical connectings, couplers and duplexers which are described as also the specifications and measurements.

To eliminate potential consalities of modal noise in telecommunication systems introduced by spatial filtering in micro-optic devices we have applied autocollimated imaging during assembly to increase accuracy. Mounting principles and facilities are discussed and the results of the first share manufactured by trained persons are given.

The increased use of digital equipment in television studio centres raises the question of how to interconnect such equipment. Because of the high bit rate, optical fibres are a possible choice. A suitable experimental link has been built. However the interconnections between equipment are not fixed; it is necessary to re-route and distribute the signals. Experiments with mechanical switching and a study of solid-state techniques show that these cannot yet switch signals on the scale needed (at least 100 sources to 100 destinations). A system based on wavelength-division and time-division multiplexing may provide a satisfactory solution.

Towards future use of optical fibers on Spacecraft and Space Stations, AEROSPATIALE Cannes has conducted various studies on the possibilities and advantages offered by this mode of transmission, as well as tests on behaviour in space environment of the components involved (transmitter, receivers, fibers, connectors).

LED wavelength multiplexing with spectral narrowing enables to reduce the material dispersion effect and increases transmission distance of a broadband link (50 MHz Bandwith) by more than 50 %.

This paper describes a high performance system for transmitting four analogue TV channels up to 5 Km using 850 nm or more than 20 Km using 1300 nm single mode fibre-optic technology without repeaters. The system, based on STL's experience in TV transmission and fibre optics is believed to be the first multichannel laser-based analogue transmission equipment in volume production.

We examinate how holographic deflection matrices could be used to perform optical space-division switching. Under realistic assumptions it seems possible to achieve by this way a capacity of 1,000 optical circuits. We are studying the feasability of such system by using photothermoplastics as holographic recording material.

The principle of a two dimensions space division optical switching system is presented, featuring rotating mirrors which deviate parallel beams. In a first step a switching system has been developed using this method and its results are presented. In a second step, a 256 x 256 capacity switching system is foreseen, which will have the same dimensions as the first one.

The potential advantages of applying coherent optical fibre techniques to broadband networks are reviewed and a number of system types are described which illustrate the operating principles. In this instance particular consideration is given to networks which rely on the use of optically tunable lasers to define either a source frequency or to select a channel from a frequency multiplexed transmission using the heterodyne receiver technique.

The design and receiver sensitivity of a novel heterodyne detection system is examined for the transmission at baseband of a single analogue colour video signal. By using optical frequency modulation a receiver sensitivity of -70.3dBm is achieved after transmission over 30km of cabled monomode fibre at a wavelength of 1.523μm. This is 21.1dB better than direct detection using the same photodetector, and is within 1.6dB of shot noise limited detection.

Employing a well-designed 1.3µm source-detector pair of InGaAsP surface emitting LED and InGaAs PIN-photodiode, we have developed a miniaturized optical data link for 300Mb/s transmission. The transmitter and receiver were packaged compactly by the use of hybrid IC technology and newly developed Si integrated circuits. In order to make the most of fiber bandwidth, the peak emission wavelength of LED was designed to be around 1310nm, and 300Mb/s transmission experiment was achieved over 5km with a margin of 6dB.

A product line is under development at [CT for cheap optical transmissions at 2/8/34 Mbit/s. Each hidirectionna] terminal is implemented on a single polyvalent hoard. Electrical interfaces are standardized HD83 junctions or Rinary + cslock (TTL) links. Optical accesses are equiped with Optical to Electrical Connections (OCC). Flexihility for PIN or PDA (arid shortly for DEL or LASER) is provided by choosing the type of DEC.

A digital optical subscriber loop system for the transmission of one broad- and 30 narrowband channels over one fiber link is described. For the 2 Mbit/s narrowband and the 140 Mbit/s broadband signal electrical frequency multiplexing has been applied. Despite the very simple filters the completed system showed satisfactory operational performance. To improve the sensitivity for the narrowband channel for emergency operation two modified concepts for transimpedance amplifiers are described.

This paper describes the transmission system (functional requirements, synchronization mode, securization, line coding) designed for the Local Integrated Optical Network (LION). This projectc, partially funded by the European Economic Community, belongs to the ESPRIT programme.

A high-speed optical IAN is described, supporting both stream and packet services. A hybrid multiple access protocol. specifically designed for service integration, is presented along with its main charac teristics. Reliability aspects are examined and solved using a network reconfiguration procedure. The transmission subsystem is analyzed, fixing the main characteristics of the network and highlighting the transmission problems.

Analog signals have been amplified by backward Raman scattering in a multimode graded index giber. A gain of over 30 dB and excellent time profile fidelity have been achieved.

The use of wavelength-division multiplexing in future fibre-optic local-area networks allows sophisticated system performance and modular system flexibility. For this purpose a wavelength selective branching coupler is required, which branches from the trunk fibre carrying multiwavelength signals to the special wavelength channels needed at the actual node. For bus or loop structured networks we developed such branching couplers, which consist of a special grating as dispersive element and micro-optical graded index lenses (GRIN rods) for light collimation and refocussing. Two different branching couplers have been designed and built. The first is a simple WDM demultiplexer in Littrow configuration with 830 nm and 1300 nm channel separation, and the second a more sophisticated arrangement, where input and output arms to the trunk as well as both first order fibre arrays have each their own graded index lens mount and adjustment facilities.

A small compact all-fibre single mode interferometer is described which uses successive couplers fabricated in tandem. Application of a voltage across one arm coated with a resistive material causes switching, due to the thermo-optic effect. We report the use of this device as a tunable wavelength filter.

Opened for commercial operation in 1984, the trial optical fiber network at Biarritz in south-west France gives 1,500 subscribers access to a whole range of broadband services - videophony, audiovisual databases, TV and stereo sound program distribution, and an on-line TV program library - in addition to conventional narrow-band services like telephony and videotex. The Biarritz network is an outstanding technology and engineering testbed. It is also a sociological testing ground for new services, unique in the world, with results of particular relevance to the interactive cable TV and visual communications networks of the future.

After a brief overview on the different sub-systems constituting the switched star network the paper describes in details the subscriber sub-system, based on fiber optics technologies, including the different components and devices involved in the fiber optic bidirectional link.

Keeping in mind a reduction of cost which makes the Telecom Network more and more succes-sful involves simplification of interconnect optical components implementation. The tendence of the technological choice : - Reduction of the space and numbers of parts - Assembly facilities and inspection means - Individual control of connection Have taken into account the demands and requirements for installators and operators.

The architecture of the Videocommunication network described, results from a french administration consultation at the end of u/ich the Group VELEC - CGCT has been retained features of this network are as follow : Programmes selection based on space switching and the 50/125 microns graded index optical fiber is used for all transmissions.

All-optical networks using single mode fibre technology provide for the first time the possibility of truly transparent communications systems. This paper considers the evolution of single mode technology towards complete optical networks based on optical space or wavelength switching. Progress towards the realisation of early experimental networks is also discussed.

The goal of this communication is to examine the different possibilities to design Integrated Services Networks, to justify the technical choices made for a Fiber's Optic Local Area Network, the CARTHAGE/LCT 6500 Network carriiing voice and data in an office automation and telematics environment and to present its extension to videocommunications facilities by tiing a star configured video switched network to the first Network.

The selective broadcast interconnection (SBI) is a scheme for directly interconnecting transmitting stations, each equipped with CT transmitters, and receiving stations, each equipped with CR receivers, such that each transmitting station is always connected to all receiving stations through passive communication channels with no intermediate switches. S BI consists of CT CR separate broadcast subnetworks, each of which interconnects a subset of transmitting stations and a subset of receiving stations, such that each transmitting station and receiving station are interconnected through a single subnetwork. Each subnetwork is shared by its transmitting members via some multiple-access scheme. Comparing S B I with CT=CR=C with the use of C broadcast buses, each connecting all transmitting stations to all receiving stations, one finds that in some cases, including that of equal single-destination traffic requirements for all source-destination pairs, the aggregate throughput with S B I can be higher by a factor of C, while the stations' hardware is the same. For nonuniform traffic requirements, however, the maximum aggregate throughput with S B 1 can be C times lower (in extreme situations). For fiber-optic implementations employing a central wiring closet, the two schemes require the same amount of fiber and, if the same elementary couplers are used to construct the required star couplers, SBI requires fewer couplers. Clearly, the same number of couplers and up to C times more fibers may be required for S B I in a linear-bus implementation. In all cases, transmitter power need only reach N/C receivers with S B I (instead of N with C parallel buses); this allows to accommodate a larger number of stations when implementing the interconnection with passive components.

The situation of communication and distribution services in Germany is shortly reviewed and an outline of the plans for the introduction of an integrated broadband digital network is given. We further present a detailed concept of such a system that includes all the required major components: broadband switching modules, multiplexers, line coders, optical transmission system, home communication system and terminals. The system is characterized by having a high modularity, thus enabling a flexible implementation to satisfy the different needs of a variety of subscribers, and allowing for a selection of new services that will eventually be available in the future.

In order to develop a broadband network as an infrastructure for the future ISDN, guidelines for the optical local network are derived from an analysis of the types of services, the required capacities, the architecture of the network and the length of the different lines. Cbncepts as defined for the ISDN are adopted. Flexibility needs are particularly emphasized. Characteristics for the topology of the local network and multiplexing schemes at the user-network interface are raised.

A number of new configurations for integrated broadband networks (IBN), using optical fibres and providing a wide range of digital communication services to commercial as well as private subscribers, is presented. These configurations are characterized by the fact that a single optical fibre is used to carry subscriber-assigned information simultaneously to a group of subscribers. Such an assignment is carried out using a combination of electrical as well as optical multiplexing techniques. This sharing of single optical fibres results in a tangible saving in the total system hardware cost per subscriber, which is an important prerequisite for the wide-spread introduction of optical fibres in the subscriber loop area.

The aim of this paper is to study a hybrid optical network architecture : the loop-star topology, in which each user is linked via a star network to a selecting and switching node, while all the nodes are linked together via a loop network. This topology, which adapts to braodcast and interactive services, fits equally well to various population densities. We'll examine the various modules of the network, and we'll describe more precisely the loop and user links using frequency and wavelength multiplexing.

A 5x5 star coupler with cascaded four port nodes is analysed using the beam propagation method in combination with confined power evaluations. Design parameters for minimum loss and equal power distri5ution at the output ports are given.

The coupling in the Holocoupler-Selfoc fiber system is studied using a new matrix method, which may be applied to arbitrary x,y,z - varying structures. The properties of the spatial transfer function for invariant linear system are used.

Analysis of optimal parameters for electro-ontic Bragg deflection in planar waveguide is made in order to decrease the losses of light intensity in waveguidr. Mode misfitting caused by interaction of light and grating with multiple period is taken into consideration. In result, the optimal parameters for an electrode array and voltage supply to interdigitated electrodes are found.

A low cost field installable single-mode fiber connector has been developed using a sphere/cone mating system. Active alignment of the fiber core is performed by means of a simple tool for the plug termination. Limited precision is required for the connector parts and the fibers. Average insertion loss of less than 0,5 dB and excellent repeatability and intermateability have been obtained.

A powerful Hamiltonian theory, recently developed, permits to predict numerically the mode coupling properties of mono and multimode optical fibers with any index pro-file. Theoretical and experimental results are presented;the observation of a sharp radiation light cone emitted by a localized point of a pseudo-periodically deformed fiber has resulted in the realization of a simple non-destructive fiber coupler with tunable splitting ratio. This coupler can be used f.i. for local temporary control on a fiber link.

450 Fbps 13 km optical frequency-division-multiplexing transmission with 11 GHz channel spacing was demonstrated at a 1.5 micron wavelength to confirm feasibility of a laser diode frequency stabilizing circuit and a narrow channel spaced optical demultiplexer. Frequency utilization efficiency was 0.08 bps/Hz.

Multimode as well as monomode multicore optical fibres /MOFs/ of circular and axially symetric distributed cores have been applied to broadband buses. The organization of the traffic was based on: multichannel and duplex transmissions, core division multiplexing (CDM), WDM signals, intercore interference, pulse delay, etc. In particular, a CI* transmission on four-fold-core multimode optical fibre was combined with four and six-fold WDM to obtain a duplex bus of small length up to a few hundred meters, of total information capacity exceeding 20 Gbit/s. The MOF buses have been applied to several practical information processing circuits like: optical fibre memory, optical fibre pulse homodyne, multiaccessible computer bus, multisensory telemetric bus, a bus of increased reliability and high quality of transmission (with very high BER value exceeding 10-11). Particular results are discussed.