Optical Fibre

Optical fibre are mainly used to transmit information over long distances and with high bit rates. Their benefits are numerous: the signal transmitted on the fiber is not disturbed by any electromagnetic wave created by power cables or electric machines. It also provides more security, as these cables can be fully dielectric. Besides, they provide a weight and space saving due to their small diameter, only 250 μm.

An optical fiber is made up of three main parts: the core, the cladding and the coating. In the center, the “core” is made of doped silica and is surrounded by the “cladding”, made of natural silica.

The light signal propagates along the core and the signal is reflected on the surface between the core and the cladding.

An acrylic “coating”, generally made of two layers, is protecting the sillica part against abrasion during installation.

Different fiber types

Multimode fibre are used for Local Area Networks (LAN) where the network links can be up to 2,000 meters. Two standard sizes of core are offered: 62.5 μm and 50 μm (with better performances). Multimode fibre have a graded index profile to
reduce the dispersion of the signal during the transmission. The high size of the core is interesting for easy connection and does not require high cost test equipment.

Singlemode fibre are able to transmit over longer distances. The installation is more delicate as they have a smaller core of 9 μm. This implies more precise connectors and test equipment.

On a global network point of view, although the cost of multimode fiber is more important than the singlemode’s, the complete system is more economic.

Indeed Multimode fibre are used with cheap transmission components LED(1) or VCSEL(2) whilst Singlemode fiber perates with more expensive LASER.

(1) LED: Light Emitting Diode
(2) VCSEL: Vertical Cavity Surface Emitting Laser

Optical fibre are used at specific wavelength. Multimodes fibre are mainly used at 850 nm and 1,300 nm and Singlemode are used at 1,310 nm and 1,550 nm. The attenuation performances are better at the higher bandwidth with consequently
improved transmission performances.

Optical fiber can be provided with different characteristics. Indeed the performance need for fiber in patch cord or fiber over one kilometer link are obviously different. The fiber choice is based on optical parameters such as attenuation, bandwidth
performances and chromatic dispersion.

Different international standards are available to describe the optical fiber characteristics: ITU G652 for Singlemode fiber and IEC 60793-2-10 for Multimode fibre are worldwide references.

Optical Fibre connectors

Nexans are able to preassemble optical fibre with plugs, we can provide this service in our factory or on site. A fiber optic connector is a non permanent join between two fibre.

In the optic connector systems gives a plurality to connector, they are not compatible among on another. It is recommendable to use ST connector or E2000 connector for reel and flexible cables with integrated fiber optics.

A high quality connector is required to achieve the best possible transfer of light signal between fibre.

ST Connector (standard)

This type of connector is suitable for both multimode fiber and singlemode fiber. The ST connector and the bajonet-holder is the most popular used connector worldwide.

E2000 Connector

An E2000 connector is a special connector with high level attenuation coefficient. This connector is suitable for multimode fiber and singlemode fiber.

Due to the code system, this connector is very user friendly and can also be fit as a single connector or duplex connector
The built-in filler cap protects the ferrule against contamination. The filler cap open/close during the connector plug in/out.