Understand optical fiber jumper and twisted pair

Let's understand the difference between optical fiber, copper cable and twisted pair. First, let's understand twisted pair. Twisted pair is a cable made of multiple groups of insulated copper wires. The internal medium of twisted pair is also copper wire. The internal transmission is electrical signal. According to the electromagnetic principle, the changing current will produce magnetic field. Therefore, by winding copper wires, the magnetic field can be counteracted in pairs and the signal interference can be reduced. Category 5 and Category 6 cables are commonly used. Category 7 jumpers can support 10G transmission and are only used in data centers. Most 10G cables use optical fiber transmission, so Category 7 cables are rarely used in actual projects.

Twisted pair can be divided into shielded twisted pair and unshielded twisted pair. Shielded twisted pair has a tin foil protective layer, which can effectively prevent data leakage and reduce the interference of external environment on data transmission. The insulating sleeve of the unshielded twisted pair has no shielding layer, which is low in price and widely used. The unshielded twisted pair is the most commonly used in our daily projects.

Next, let's learn about optical fiber. Optical fiber is a light transmission tool based on the principle of total reflection of light in glass fiber. The transmission loss of light in optical fiber is much lower than that of electricity in wire, so optical fiber is used for long-distance information transmission. Optical fiber jumper has the characteristics of light weight, small volume, long transmission (small attenuation), large capacity, anti electromagnetic interference, etc. Optical fiber can also be divided into single-mode optical fiber and multimode optical fiber. Single mode optical fiber only allows one mode of propagation and has extremely wide bandwidth, which is particularly suitable for high-capacity, long-distance optical fiber communication. Single mode optical fiber can be used together with single mode optical modules, supporting transmission distances of 10KM, 40KM, 80KM, and even 160KM.

Multimode optical fiber allows multiple modes of optical signal propagation. OM (Optical Mode) means optical mode. It is the standard for multimode optical fiber to represent the optical fiber grade. OM1, OM2, OM3, and OM4 have four grades of multimode fiber respectively, and the bandwidth and maximum distance are different for different grades of transmission. Multimode optical fiber can be used with multimode optical modules. Generally, multimode optical modules below gigabit are used with OM2 multimode jumpers, 10G-40G multimode optical modules are used with OM3 multimode jumpers, and optical modules above 40G are used with OM3/OM4 jumpers.