Similarities and Differences of OM3 and OM4 Multimode Fibers

      "OM" (Standard For Optical Multi-mode), i.e. multi-mode fiber grade standard. Different grades have different bandwidths and maximum distances for transmission, corresponding to different scenarios of use. In accordance with the TIA and IEC definition of fiber optic patch cord standards, there are OM1, OM2, OM3, OM4, OM5 five standards, the following commonly used in the market OM3 and OM4 fiber to talk about the similarities and differences between them.
      I. The same point
      OM3 and OM4 multimode fiber is commonly used in the local area network of the two kinds of optical fiber, usually used in telecommunications rooms and data centers between the main network and storage area network (SAN) switches backbone network cabling. Both types of fibers are laser-optimized 50/125 multimode fibers with a core diameter of 50 µm and a cladding diameter of 125 µm, and are paired with a transceiver that is a Vertical Cavity Surface-Emitting Laser (VCSEL), which emits infrared light at a wavelength of 850 nm.

Figure 1 50/125 multimode fiber

      II. Different points
      2.1 Different appearance
Most of the OM3 and OM4 optical fiber jacket color is aqua blue, but in Europe and some U.S. companies proposed a jacket color of violet OM4 fiber. Motech Optoelectronics can provide these two coat colors of optical fiber.

Figure 2 OM3\OM4 - aqua blue color


Figure 3 OM4 - violet color

      2.2 Different transmission performance
      The minimum effective mode bandwidth of OM3 is 2000MHz.Km@850nm, and the minimum effective mode bandwidth of OM4 is 4700MHz.Km@850nm, OM4 fiber optic patch cord can transmit more information in the same distance. The transmission distance of the same module in these two kinds of fiber is also different, take SFP28-25G-SR module for example, it can transmit 70m in OM3 fiber and 100m in OM4 fiber.
      2.3 Different prices
      The production cost of OM4 fiber is higher compared to OM3, and the production volume is not as large as OM3, so for the same length of fiber, the price of OM4 is much more expensive than OM3.
      Therefore, in network construction, you need to choose the right fiber optic patch cord according to your own needs in order to save costs and maximize the use of fiber optic resources.
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