Multimode fiber has been developed from OM1 to OM5 now, so which one is better among OM2, OM3, and OM4 multimode fiber? In this blog, ETU-LINK will explain to you.

Multimode fiber is mainly used for optical transmission with a wavelength of 850nm. Here, the two points of effective mode bandwidth and full injection bandwidth can be compared separately. First, let us understand what bandwidth is. The bandwidth of light is the product of the modulation frequency of the maximum modulation frequency pulse that a section of fiber can pass and the length of the fiber. It is a comprehensive index that characterizes the optical characteristics of multimode fiber. For example, the light transmitters of ordinary optical cables are generally LEDs (light-emitting diodes), it is required that the optical cable must reach at least 200MHz bandwidth at 850nm, and the optical transmitter of OM3 optical cable is VCSEL (Vertical Cavity Surface Emitting Laser), which requires the optical cable to reach 2000MHz at 850nm. At present, the bandwidth of optical fiber is only available in multimode optical fiber, while the bandwidth of single-mode optical fiber is unlimited.

The effective mode bandwidth of OM2 is 950 MHz•km, and the full injection bandwidth is 700 MHz•km; the effective mode bandwidth of OM3 is 2000 MHz•km, and the full injection bandwidth is 1500 MHz•km; the effective mode bandwidth of OM4 is 4700 MHz•km , the full injection bandwidth is 4700 MHz·km. Basically, every time a level of multimode fiber is upgraded, its performance will be improved in all aspects.

The fiber core of OM2 is conventional 50/125um; OM3 is a 50um core diameter multimode fiber optimized by 850nm laser, which is mainly used in 10Gb/s Ethernet transmission of 850nm VCSEL laser, and the fiber transmission distance can reach 300m; OM4 is OM3's The upgraded version optimizes the differential mode delay (DMD) of OM3 multimode fiber during high-speed transmission, so the transmission distance is greatly improved, and the transmission distance of the fiber can reach 550m.

OM2 multimode fiber is often used in multimode optical modules with transmission rates below 10G (excluding 10G), while OM3 and OM4 multimode fibers are used in multimode optical modules with 10G and above. If OM4 optical fiber is used for transmission, Usually the transmission distance will be longer than with OM3. From the comprehensive consideration of transmission performance and transmission distance, multimode OM4 fiber is the best compared to OM3 and OM2, by OM3, and finally OM2. OM3 and OM4 are mainly used in multimode cabling systems in data centers, and OM2 will be used later. was gradually eliminated.