OM2/OM3/OM4/OM5 transmission capability comparison

1. The past and present of OM2 fiber

The OM2 fiber is the traditional 50/125 mm graded index multimode fiber. The traditional OM2 fiber is based on the LED method in terms of standard and design, and has low bandwidth requirements. It cooperates with the LED for 100Mbit/s and lower transmission rates. .

2. OM3 fiber, born for VCSEL laser

With the maturity and commercialization of the 850nm Vertical Cavity Surface Emitting Laser (VCSEL), the 850nm VCSEL laser immediately became the main light source for multimode communication systems. The spot size of VCSEL laser is about 30mm, which has the advantages of good stability, long life and low price.

In order to improve the transmission capacity and distance of multimode optical fiber transmission systems based on 850nm VCSEL lasers, OM3 optical fibers came into being. In order to cooperate with the 850nm VCSEL laser, compared with the traditional OM2 fiber, the OM3 fiber mainly made the following improvements:

1. For the 850nm wavelength, the design of the optical fiber is optimized, so that the optical fiber has the best wavelength bandwidth of 850nm.

2. According to the mode characteristics of VCSEL lasers, the "effective mode bandwidth" is introduced. The "effective mode bandwidth" is used to evaluate the bandwidth of multi-mode fibers when using VCSEL lasers. Transmission performance when using VCSEL lasers. The later OM4 fiber continues to improve the index requirements of "effective mode bandwidth" on the basis of OM3 fiber. And OM2 fiber has no requirement for "effective mode bandwidth".

3. Comparison of OM2/OM3/OM4/OM5 transmission capabilities

OM3~OM5 are designed based on VCSEL laser as light source. OM5 fiber is called broadband multimode fiber, which has high bandwidth in the wavelength range of 850~950nm, and adopts wavelength division multiplexing technology in the wavelength range of 850~950nm to carry out high-speed transmission of 100Gb/s and above.

According to the IEEE 802.3 series of Ethernet standards, the transmission distance of OM2~OM5 optical fibers in 10G~400G systems is shown in Table 1. In 40G, 100G, 400G systems, the parallel technology and wavelength division multiplexing technology are used.

4. OM2 fiber: not suitable for new data centers

The connection within the data center has entered the 25G+ era. OM2 fiber has low bandwidth and is not optimized for VCSEL lasers. According to IEEE related standards, it is not suitable for 25Gb/s and above systems. OM2 fiber can no longer be used for new data centers and upgrades of existing data centers. When selecting multimode fiber, OM3 or OM4 or OM5 fiber should be selected according to the actual speed and distance.

5. The quality problem of multimode fiber threatens the security of data center

The "effective mode bandwidth" test of multimode fiber requires expensive instruments, and the length of the test sample needs to be at least hundreds of meters, while the multimode fiber patch cords on the market are usually only tens of meters. Therefore, the "effective mode bandwidth" of these patch cords Bandwidth" cannot be tested, so it is impossible to directly identify whether the OM3 and OM4 fiber optic patch cords on the market are true or false, which brings opportunities to some multimode fiber optic patch cord suppliers. Shoddy OM3 and OM4 fiber jumpers (many are actually OM2 fiber jumpers) threaten the safety of data center operations.

ZR Cable uses PCVD process to make multimode fiber. PCVD process has the advantages of thin deposition layer, strong process control, accurate refractive index profile, etc. It is the best process for manufacturing high bandwidth multimode fiber. ZR Cable continues to upgrade the PCVD platform and process, improve and optimize the multimode fiber design and process, increase the investment in the multimode fiber test platform and test method research, and ensure the quality of the multimode fiber. ZR Cable will work with users to create safe data. center.