Nothing has changed the world of communications more than the development and implementation of fiber optic. The introduction of fiber optics has dramatically increased the speed of network transmission. Relying on optical transmission, the speed of data transfer has increased significantly.
This article provides the basics of this technology, so read on.
Concept of fiber optic
An optical fiber (Optical fiber / Fibre optics) is the abbreviation for optical fiber. It is a kind of glass (silicon dioxide) made of fibers that can be used as a light conduction tool.
Optical fiber transmission (Optical fiber transmission) uses optical fibers as a data and signal transmission medium. It can transmit analog and digital signals and meet video transmission needs. Fiber optic transmission is generally carried out using fiber optic cable; a single optical fiber data transmission rate can reach several Gbps, and without repeaters, the transmission distance can reach dozens of kilometers.
Transmission principle of fiber optic
Optical signals from one medium into another will simultaneously produce refraction and reflection phenomena.
When the refractive index of medium 1 is higher than medium 2, the refraction angle will be greater than the angle of incidence. When the incident light from the critical angle of incidence to the interface of medium 1 and medium 2 is refracted at an angle of 90 degrees, this time, the information will not enter medium 2.
The total reflection occurs when the incident angle exceeds the critical angle. The light information transmitted in medium 1 does not enter medium 2. Light transmission’s optical fiber communication principle uses the fiber optic all-reflective effect.
Composition of the fiber optic
The core, cladding, and coating layers are ordered from the inside to the outside.
The coating layer’s role is to increase the fiber’s institutional strength and bendability and to protect it.
Core and cladding are high-purity silica. They contain different dopants, making the refractive index’s core higher than the cladding. When the light signal enters the core at the right angle of incidence, it can form a total reflection between the core and cladding, thus realizing light transmission.
Classification of fiber optic
We can divide optical fiber into different types according to various criteria. In the communication of light propagation mode, “multimode fiber” is commonly used to divide optical fiber into single-mode fiber and multimode fiber.
Multimode fiber
the standard light wavelength of Multimode fiber is 1310nm or 850nm, the core diameter is 50um or 62.5um, and its diameter is much larger than the wavelength of light, in this case, allowing light signals to be incident at more than one angle into the optical fiber for transmission, this different angle of light signals we call the other modes, so this kind of optical fiber is called multimode fiber.
Due to multiple modes transmitting signals at different speeds, the multimode fiber in the transmission of signals causes the resulting dispersion to be relatively large, with time delays, low rates, and other issues. Multimode optical fiber is generally used for short-distance transmission (multimode optical fiber color is usually orange, purple, aqua, and green).
Single-mode fiber
the standard light wavelength of Multimode fiber is 1310nm or 1550nm, and the core diameter is 9um. It is similar to the wavelength of light for communication. In this case, the fiber only allows optical signals to be transmitted in the same direction as the optical fiber axis.
In simple terms, single-mode optical fiber data transmission mode is the transmission of data along the optical fiber axial in a straight line, the transmission of large capacity, long distance, the most commonly used medium in transmitting current optical signals. It is the most frequently used medium for optical signal transmission. Marked with the word SM (the color of single-mode fiber is usually yellow).
Connector for optical fiber
The role of the fiber optic connector is to connect two optical fibers so that the signal energy of the transmitting light can maximize the coupling to the receiving fiber, achieving the interconnection between different optical interfaces.
Fiber optic connectors can be divided according to their interface type:
- FC (Ferrule Connector): round, threaded connection.
- SC (Square Connector): square, axial insertion and removal.
- LC (Lucent Connector): square, axial plugging, high density.
According to the design of the cross-section of the fiber when it is docked, the fiber can be divided into:
- FC type (Flat Contact): flat contact.
- PC type (Physical Contact): spherical contact.
- APC type (Angle Physical Contact): oblique spherical contact.
Fiber patch cable and optical attenuator
Fiber patch cables are mainly used to connect two different fiber optic interfaces. The different interfaces at both ends can be divided into FC-SC, FC-LC, and FC-FC.
A fiber attenuator is mainly used to attenuate optical signals. It must keep the receiving end’s optical power in the appropriate range to avoid overload. The optical attenuator can be divided into fixed, mechanically adjustable, electrically adjustable, and SFP attenuator.
Conclusion
Fiber optic composition is delicate and rich in type. A fiber optic connector can be connected to two optical fibers to extend the transmission distance. I hope this article helps you understand fiber.