How Does Optical Fiber Transmit Signal?

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The word “Internet” is not known at the moment, but it is unclear to ask what it is. We know that it can do a lot of things online, and the use of Internet technology has created many super-big companies. This is our impression of the Internet. The Internet is really like a cell phone signal, can’t you see it?

In fact, in addition to the base stations we know, there are also optical cables that are transmitted over long distances. Submarine cables connected between continents have more than 380 submarine cables around the world, responsible for 95% of language and data transmission between continents. We are watching a foreign football match, TV show, calling overseas, and the network used is transmitted through submarine cable.

submarine cable

The optical cable is a communication cable composed of two or more glass, plastic optical fiber core and wrapping layer. The internal signal transmission of the optical fiber generally adopts laser, which has the characteristics of higher speed, larger capacity and long-distance transmission.

The single fiber data transmission rate can reach several Gbps, and the submarine cable transmission reaches an astonishing 160 TBps, and the transmission distance can reach several tens of kilometers without using a signal amplifier. (1G=1024M 1T=1024G)

The History of Fiber

In ancient times, there was no Internet, no optical cable, and it was only used to fly the pigeons. With the rapid development of science and technology, human beings have entered the information age. As the amount of information increases, it is necessary to find a new transmission method. After years of research, the transmission speed is faster and the transmission volume is larger, and the loss is higher. Fiber optic communication was born, and humans have entered the era of light.

  • In 1870, British physicists discovered the principle of total reflection of light, which laid the foundation for future fiber transmission signals.
  • In 1880, the invention of the “optical phone” is to use the beam to transmit sound waves.
  • In 1970 Corning developed a quartz glass fiber with less attenuation.
  • The first fiber optic cable began commercial use in 1980
  • Successfully laid the transatlantic submarine cable connecting the Anglo-American in 1988

How does the fiber work?

If the Internet is likened to the information superhighway, the optical cable is like the cornerstone of the expressway. How is the high-capacity information optical cable transmitted at high speed and long distance?

How does the fiber work

At the transmitting end, the information to be transmitted (such as voice) is first converted into an electrical signal, and then transmitted to the laser beam through the laser. The intensity of the light changes with the frequency of the electrical signal and is transmitted through the optical fiber. At the receiving end, the detection is performed. After receiving the optical signal, the device turns it into an electrical signal, and after processing, restores the original information.

The optical fiber made of glass fiber inside the fiber can transmit optical signals to thousands of kilometers, and combine hundreds of thousands of optical fibers to form a cable with the same cable, which improves the strength of the optical fiber and greatly increased the communication capacity.

The speed of light propagation in different materials is different, so when one substance is shot to another, the intersection of the two substances will refract and reflect, and the angle of the refracted light will change with the angle of the incident light. However, when the angle of the incident light reaches or exceeds an angle, the refracted light will disappear and the incident light will be reflected back. This is the total reflection of the light.

The optical signal is transmitted to the end point after repeated refraction in the optical fiber. The optical signal is dispersed or attenuated after the primary refraction, and the optical signal needs to be amplified every 50 kilometers.

How to manufacture an Optical fiber?

First, the embryo body of the optical fiber preform is mainly made of high-purity silica, and is fired into an optical fiber preform at a temperature of 1500 °C.

How to manufacture an Optical fiber

After 20 hours, the high-purity light bar was successfully fired. The 3m diameter 20cm light rod was suspended into the drawing furnace. The airing tube could be drawn continuously for 7500km within 48 hours. Prevent impurities and dust from falling onto the fiber. The light bar melts into a soft embryo at a high temperature of 2200 degrees Celsius. After passing through a 1 meter long annealing tube, it is gradually cooled into a glass filament with a diameter of 0.1 mm. The wire take-up rotates to drive the fiber and complete the fiber. Collection.

What is the difference between Optical Cable and Fiber?

If a fiber optic cable is used for a while, is it a bit embarrassing to see it? What is the difference between them?

The optical cable is composed of a certain number of optical fibers, and is covered with a sheath and a protective layer for communication and long-distance large-capacity information transmission.

fiber cable

Optical fiber is a transmission tool, just like a thin plastic wire. A very thin fiber is encapsulated in a plastic sleeve for long-distance information transmission. So the optical cable includes fiber-optic.


Do you have other questions of the Fiber? Welcome to leave your comment.

Learn More:

Ethernet Cable or Fiber Optic Cable? Ethernet vs. Fiber

A Quiz for Test Your Knowledge of Fiber Optic Cables


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