The new wavelength-division multiplex technique applied to fiber-optic communication systems frequently allows more efficient utilization of the large transmission capacity of glass fibers. The physical design, operating principle, and properties of the various microoptical wavelength-division multiplex and demultiplex couplers are surveyed, and the criteria on which their practical application depend are defined.

Fiber-optic communication in the wavelength-division multiplex mode

Low-loss lensless 2-channel wavelength-division multiplexing (WDM) couplers may be produced on the beam-splitter principle with interference filters and three butt-coupled fiber ends not only for multi-mode Operation but also for single-mode transmission links. These devices are constructed with single-mode fibers-for bidirectional transmission only in the transmission channel, but for unidirectional operation in all channels. The interference filter, used in the experiment to separate the emissions of two LD's with wavelengths of 834 and 868 nm, may be implemented both as a longwave-pass (LWP) and a shortwave-pass (SWP) edge filter with high edge steepness and low polarization effects. WDM single-mode couplers exhibit very low insertion losses lying in the O.5-dB region. Their fat-end crosstalk attenuations attain values of between 15 and 30 dB and their near-end crosstalk attenuations are better than 65 dB.

Wavelength-division multi demultiplexers for two-channel single-mode transmission systems

Un multiplexeur a filtres fonctionnant sur trois canaux est decrit. Il est base sur le couplage de la fibre de ligne avec chacune des fibres d'emission ou de reception par des miroirs concaves travaillant au centre de courbure et presente peu d'aberration. L'extraction de chaque longueur d'onde ou son injection dans la ligne se fait par reflexion selective sur les miroirs a couches multidielectriques. Le composant appele « TRIMAX » a ete concu pour fonctionner a 0,825, 0,87 et 1,3 μ. Les pertes sont inferieures ou egales a 0,3 dB pour la premiere voie, 0,75 dB pour la deuxieme voie et 1 dB pour la troisieme. Un taux de para-diaphonie aussi bas que — 78 dB a ete mesure entre voies proches. La distance intracanaux a — 50 dB de paradiaphonie et 1 dB de perte peut etre reduite jusqu'a 25 nm. Un composant appele « BIMAX », destine a separer 0,8 de 1,3 μ a egalement ete fabrique. Les pertes sont bien inferieures a 1 dB pour les deux voies et le taux de rejection de 0,8 sur 1,3 μ tres eleve.

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Un multiplexeur 3 voies à faibles pertes

In the history of optical fiber communications, there were key milestones in system R&D that helped usher in new phases of the field. Critical advances such as terrestrial systems, WDM, submarine systems, coherent communication and fiber in the access will be highlighted.

Milestone system advances

http://link.springer.com/content/pdf/10.1007/978-3-642-93166-6_9.pdf

A. Reichelt

Papers

Wavelength-division multiplex transmission over multimode optical fibers - Comparison of multiplexing principles