With the continuous growth of network high bandwidth and high speed requirements, optical fiber is widely used in network cabling as a network transmission medium.The following is a detailed introduction of multi-mode optical fiber and the difference between multi-mode fiber and single-mode fiber.
What is multi-mode fiber?
Multi-mode fiber (MMF for short) is a common fiber type. Its working wavelength is 850nm/1300nm, supports hundreds of transmission modes, has the advantages of high bandwidth and low cost, and is suitable for short-distance fiber transmission (such as computer rooms). The refractive index of multimode fiber is divided into two types: gradient and step.
Difference between multimode fiber and single mode fiber
As mentioned in the above introduction of multi-mode fiber, the transmission mode of multi-mode fiber can be as many as hundreds, while the transmission mode of single-mode fiber is single. The difference between multi-mode fiber and single-mode fiber is in addition to the difference in transmission mode, there are also the following six differences:
Different core diameters
Although the cladding diameter of multi-mode fiber and single-mode fiber are the same, the diameter is 125 μm, but the core diameter of multi-mode fiber is much larger than that of single-mode fiber. The core diameter of single-mode fiber is generally 9 μm. The core diameter of a multi-mode fiber is generally 50μm/62.5μm.
Different transmission distance
As can be seen from the above table, single-mode fiber has a long transmission distance and is suitable for long-distance transmission, while multimode fiber has a shorter transmission distance and is suitable for short-distance transmission, and OM3/OM4/OM5 multimode fiber can be Support high-speed data transmission.
Different light source
Multimode fiber generally uses LED (light emitting diode) or vertical cavity surface emitting laser (VCSEL) as the light source, because LED light source can generate many modes of light (light is more scattered); singlemode fiber generally uses laser or laser diode as the light source, because The laser light source can generate a single mode of light, and has the advantages of high brightness and high power.
The core of a singlemode fiber is generally a single material, and the refractive index of a multi-mode fiber is divided into two types: gradient and step.
The dispersion of the fiber is a factor that affects the bandwidth of the fiber. The smaller the dispersion of the fiber, the wider the bandwidth of the fiber. Single-mode fiber has almost no dispersion, so the bandwidth of single-mode fiber is wider than that of multimode fiber.
As mentioned above, single-mode fibers use lasers or laser diodes as light sources, and multi-mode fibers use LEDs (light emitting diodes) or vertical cavity surface emitting lasers (VCSELs) as light sources. The price of lasers is higher than that of LEDs. The cost of single-mode fiber is higher than that of multi-mode fiber.
What are the advantages of multi-mode fiber?
From the above introduction of the difference between multimode fiber and multimode fiber, it is obvious that single mode fiber has more advantages than multimode fiber, but in fact, multimode fiber also has some advantages.
1.For local area networks or metropolitan area networks, both single-mode and multi-mode fibers can be implemented. However, because single-mode fiber is afraid of bending and has high requirements for fusion splicing, it is prone to additional loss. Therefore, the use of single mode fiber will increase the difficulty of wiring and maintenance and management. If multimode fiber is used, such a problem does not exist.
2.The use of single-mode optical fiber requires high cleaning, while multi-mode optical fiber can be inserted with just a wipe.
3.The cost of a single mode laser transceiver for a multimode fiber is lower than that of a single mode fiber, and the power consumption of a multimode laser is less than that of a single mode laser.
How to choose between multimode fiber and single mode fiber?
Understand the difference between multi-mode fiber and single-mode fiber, so that you can choose between the two. According to the actual application scenarios, single-mode fiber is suitable for long-distance (above kilometers) data transmission, and can be applied to metropolitan area networks, passive optical fiber networks, etc.; multimode fiber is suitable for short-distance (300~400m) data transmission, application Used in enterprises, data center computer rooms, etc. According to the budget choice, in scenarios where both multi-mode fiber and single-mode fiber are applicable, since the cost of single-mode fiber is higher than that of multimode fiber, it is more ideal to choose multimode fiber.