Shulou(Shulou.com)11/24 Report--

The original title: "come and tell me, is this complete?" "

There is no copper in the optical fiber, it is useless to steal it! Nowadays, such slogans can be seen in the streets, and this is the first understanding of optical fiber.

We all think that optical fiber seems to be far away from our lives, but in fact, optical fiber is affecting our lives at an amazing speed, from communication networks, television networks to the Internet, from online games to high-definition televisions, from 4G telephones to remote monitoring. Optical fiber is becoming the basis of human information communication. Every day, data such as music, pictures and videos are transmitted through optical fiber, precisely because the laying of optical fiber network can spread all over the world in an instant.

Optical fiber has no copper. What does it have? Optical fiber is a kind of fine and soft solid glass material, which is composed of fiber core, cladding and coating layer, and can be used as a light conduction tool.

Fiber core: located in the center of the optical fiber, the composition is high-purity silica, namely glass.

Cladding: located around the fiber core, its composition is also high-purity silica that is glass. Cladding provides reflector and light isolation for light transmission, and plays a certain role of mechanical protection.

Coating: the outermost layer of an optical fiber, consisting of acrylate, silicone rubber and nylon. The coating protects the optical fiber from water vapor and mechanical abrasions.

How does optical fiber transmit light? The realization of optical fiber communication is based on the principle of total reflection of light.

When the light propagates into the center of the optical fiber, the refractive index N1 of the optical fiber core is higher than that of the cladding N2, and the loss of the fiber core is lower than that of the cladding, so the light will have a total reflection phenomenon, and its light energy is mainly transmitted in the fiber core by means of continuous total reflection. Light can be transmitted from one end to the other.

How is optical fiber classified? Classified by transmission mode: single-mode fiber and multimode fiber.

The core diameter of single-mode fiber is small, so it can transmit only one mode of light wave.

Multimode optical fiber has a large core diameter and can transmit various modes of light waves.

You can also distinguish between single-mode fiber and multimode fiber by appearance color:

Most of the single mode optical fibers are yellow coat and blue joint, and the cable core is 9.0 μ m. There are two central wavelengths of single-mode fiber: 1310 nm and 1550 nm,1310 nm are generally used for short, medium or long-distance transmission, and 1550 nm are used for long-distance and ultra-long-distance transmission. The transmission distance depends on the transmission power of the optical module. The transmission distances of 1310 nm are 10 km, 30 km, 40 km, etc., and those of 1550 nm are 40 km, 70 km, 100 km, etc.

Most of the multimode optical fibers are orange / gray coat and black / beige joint, and the cable cores are 50.0 μ m and 62.5 μ m. The central wavelength of multimode fiber is generally 850nm. The transmission distance of multimode optical fiber is short, which is generally less than 500 m.

Classified according to ITU-T international standards: G.651, G.652, G.653, G.654, G.655, G.656, G.657.

ITU standard

Optical fiber type

Name

Working with scen

G.651

Multimode

Long wavelength multimode fiber

It is suitable for short-distance transmission with light wavelength of 850 nm or 1310 nm and is used in local area network.

G.652

Single mode

Dispersive non-shifted single mode fiber

It is suitable for transmission with light wavelength of 1310 nm ~ 1550 nm and is used in access network.

G.653

Single mode

Dispersion-shifted single-mode fiber

It is suitable for long-distance transmission with light wavelength of 1550 nm, used in backbone network, and supports DWDM.

G.654

Single mode

Cutoff wavelength shift fiber

It is suitable for long-distance transmission with light wavelength of 1550 nm. It is used for submarine cable and does not support DWDM.

G.655

Single mode

Non-zero dispersion shifted fiber

Suitable for long-distance transmission with light wavelength of 1550 nm, for backbone network or submarine cable, supporting DWDM.

G.656

Single mode

Low slope non-zero dispersion shifted fiber

A kind of non-zero dispersion shift fiber has strict requirements for the speed of dispersion, which ensures the transmission performance in a wider wavelength range of DWDM systems.

G.657

Single mode

Bend-resistant optical fiber

The minimum bending radius is 5 mm~10 mm. G.657 is a new product based on the requirements of FTTx technology and assembly applications.

What if the optical fiber is broken? During the engineering maintenance, we often encounter the interruption of the optical fiber, so we can use the optical fiber fusion machine to reconnect the optical fiber.

The principle of the welding machine is that the welding machine should correctly find the core of the optical fiber and align them accurately, and then melt the optical fiber and push it forward through the high voltage discharge arc between the electrodes.

For normal optical fiber fusion, the position of the fusion point should be smooth and neat and the loss should be low:

In addition, the following four situations will lead to greater loss of optical fiber fusion joints, which need to be paid more attention to:

The size of the fiber core at both ends is different.

There is an air gap between the two ends of the fiber core.

The core centers at both ends are not aligned.

The core angle at both ends is not aligned.

Precautions in the use of optical fiber it is strictly forbidden to pull the optical fiber, which is easy to cause the optical fiber to crack.

It is strictly forbidden to twist optical fiber lines to avoid possible twisting of optical fiber wires. The coiled fiber should be carried out along the natural relaxation state of the optical fiber.

After using the optical fiber, we must use a dust cap to protect the optical fiber connector, dust and oil will damage the coupling of the optical fiber.

If the optical fiber connector is dirty, you can use a wiping box or cotton swab dipped in alcohol to clean, otherwise it will affect the quality of communication.

With its low-cost glass material, optical fiber is easy to measure and easy to maintain, which makes it widely used in communication networks and brings great changes to our lives.

This article comes from the official account of Wechat: ZTE documents (ID:ztedoc)

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.