May 14, 2023

As a qualified low current person, you only need to understand knowledge of these optical fibers.

In weak current smart system project, everyone has encountered many situations with fiber optic cables, so what do you know about fiber optic cables? As a low current installer, some professional knowledge of optical fiber is needed!

As a qualified low current person, you only need to understand knowledge of these optical fibers.

One, fiber optic cable

Light that is often transmitted by optical fiber: only this kind of radio waves, wavelength range of invisible light part is 390~760nm (nanometer), part above 760nm is infrared, and part below 390nm is ultraviolet. Fiber optics is used in: 850nm, 1300nm, 1550nm.

The wavelength of light used in single mode fiber is 1310nm or 1550nm, and wavelength of light used in multimode fiber is mainly 850nm. The shorter wavelength of light, higher level of color refraction and greater attenuation coefficient of light, so optical wavelength of 1550 nm instead of 850 nm is used to transmit data over fiber over long distances.

Second, fiber type

According to mode of transmission of light in fiber optic line, it can be divided into: multi-mode fiber (MMF, Multi Mode Fiber) and single-mode fiber (SMF, single mode fiber). The central glass core of a multimode fiber is relatively thick (50 or 62.5 µm) and can transmit light in various forms. However, inter-mode color shift is very large, which limits transmission frequency of analog signals, so transmission distance of multimode fiber is relatively short, usually only a few kilometers. Single-mode fibers have a thin glass core (typically 9 or 10 µm in diameter) in center and can only transmit light in this mode. Therefore, color fold between forms is small and suitable for remote control communication. Under normal conditions, orange skin is a multi-group module, and yellowish skin is a multi-mode module.

3. Introduction to optical module

An optical module consists of optoelectronic devices, functional power circuits and optical connectors. Optoelectronic devices consist of two parts: a transmitting point and a receiving part. Simply put, function of an optical module is optical conversion: transmitting end converts electronic signal to optical, and after transmission through fiber optic line, receiving end converts optical signal to electronic.

Optical modules are mainly divided into: GBIC, SFP, SFP+, XFP, SFF, CFP, etc. Sundray Technology recommends using current common models such as SFP and SFP+. Under normal circumstances, GBIC will not be used because GBIC is bulky and easy to break, while regular SFP is light weight and relatively cheap.

4. Getting to know optical connector

A fiber optic interface is a physical jack used to connect fiber optic cables. Its basic principle is to use light from an optically dense medium to an optically rarefied material to reflect light. Generally, there are several types such as SC, ST and FC which are standards developed by various companies at an early stage.

WholesaleFC type elbow connector/leakage wire (also known as round neck): external lifting method is to use a metal material sleeve, and tightening method is into a lanyard, which is usually used on side of ODF. The three-pin FC connector is commonly used in telecommunication networks. A screw cap is screwed onto power adapter. The advantage is that it is durable and dustproof. The disadvantage is that installation cycle is a little longer.

ST type fiber optic connector/leakage wire: typically used to connect multiple modules and components. After ST connector is inserted, there is an interface that is fixed at half a circle. The disadvantage is that it is very easy to break. When deploying a Wi-Fi network, there are many applications when connecting to machines and equipment from other manufacturers.

SC type fiber connector/leakage wire (also known as square head atmospheric): The optical connector on side of transmitter generally uses SC connector, and three-way SC connector is directly inserted, which is very convenient to use, but disadvantage is that which falls off easily.

LC type fiber optic connector/leakage wire (also known as square head, Xiaoai): A special connector for SFP modules, which is much smaller than above types of connectors and can accommodate a larger area of ​​the same area. on network switch Port number, Sundray process equipment uses this connector.

The number of fiber optic FC connectors is most on fiber optic distribution frame; number of SC fiber optic connectors is most on wireless routing switch; ST fiber optic connectors are generally all Yes, this is also common in fiber optic distribution frames; LC type fiber optic connectors are common in wireless routing. Generally speaking, when you choose fiber optic interface and optical interface, you should also pay attention to your own requirements and not blindly choose best interface can achieve best effect.