Single-mode optical module meaning and application
Single-mode in optical modules actually refers to the fiber type only. Single-mode optical modules are optical modules used together with single-mode optical fibers, using LD or LEDs with narrow spectral lines as light sources, which can transmit data signals with extremely high bandwidth and therefore long distances. The single-mode optical module is identified as “SM” and the fiber is yellow, mainly at wavelengths near the 1310nm and 1550nm windows.
The bandwidth potential of single-mode optical module makes it a choice for high-speed and long-distance data transmission, mostly used in LR, ER/ZR and other long-distance transmission, transmission rate is relatively high in the line, such as long-distance trunk transmission, metropolitan area network construction, etc.. It has a wide range of applications, including telecommunications, cable TV, railroads, military, finance and securities, customs, civil aviation, shipping, electric power, water conservancy and oil fields, and various broadband data networks and fields requiring high reliability data transmission or the formation of dedicated IP data transmission networks, and is the ideal application equipment for broadband campus network, broadband cable TV network and intelligent broadband community fiber to the building, fiber to the home.
Multimode optical module overview
This kind of optical module is called multimode optical module, which can transmit various modes of light, and the appearance is shown in the figure below. Multimode optical modules are generally used for short-distance transmission because they limit the frequency of transmitted digital signals due to large inter-mode dispersion.
What is the difference between single mode and multimode in optical modules
1、Difference in wavelength
Generally, the wavelength of multimode light is 850nm, while the wavelength of single-mode light is mainly 1310nm and 1550nm. Multimode optical module can only be used for short-distance transmission (SR) because of the serious inter-mode dispersion; while single-mode optical module is mostly used for LR, ER, ZR and other long-distance transmission. Usually, the transmission distance below 2km is called multimode module; the transmission distance above 2km is called single-mode module.
2、Different application scope
Multimode optical modules are mostly used in networks with relatively low transmission rate and relatively short transmission distance, such as local area networks, which usually have more nodes, connectors, bends, connectors and couplers, as well as the number of light sources per unit fiber length, etc. The use of multimode optical modules can effectively reduce network costs; single-mode optical modules are mostly used in networks with long transmission distance and relatively high transmission rate. Single-mode optical modules are mostly used in long transmission distance and relatively high transmission rate, such as long-distance trunk transmission, metropolitan area network construction, etc.
3、Different fiber types
The single-mode in optical module actually refers to the fiber type only. According to the optical module in the fiber transmission mode can be divided into single-mode fiber and multimode fiber.
Multimode fiber is referred to as MMF, fiber diameter is generally 50/125μm or 62.5/125μm.
Single-mode fiber is referred to as SMF, fiber diameter of 9/125μm.
4, the cost is different
Single-mode optical modules use twice as many devices as multimode optical modules, so the overall cost of single-mode optical modules is much higher than multimode optical modules.
5, the light source is different
The light source of multimode optical module is light-emitting diode or laser, while the light source of single-mode optical module is LD or narrower spectral line LED.
6、Different transmission distance
Single-mode optical modules are often used in long-distance transmission, transmission distance up to 150 to 200km. multimode optical modules are used in short-distance transmission, transmission distance up to 5km.
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