Difference Between Single Mode Fiber and Multi Mode Fiber

Single-mode fiber is mainly used in multi-frequency data transmission applications, the transmission mode is usually used wavelength division multiplexing (WDM, Wave-Division-Multiplexing) transmission mode, through the reuse of optical signals only need a single-mode fiber can To achieve data transmission. Released in 2010, 100GBase-LR4, the use of 2-core single-mode fiber 1 received 1 fat, in a core fiber at the same time multiplexed four wavelengths, each wavelength transmission 25Gbps.

Single-mode fiber transmission rate is higher than the multi-mode fiber, and the transmission distance than the multi-mode fiber to be more than 50 times higher, therefore, the price is higher than multimode fiber. Compared with multi-mode fiber, single-mode fiber core diameter is much smaller, small core and single-mode transmission characteristics of single-mode fiber in the optical signal transmission will not be because of optical pulse overlap distortion. In all types of fiber, the single-mode optical fiber signal attenuation rate of the minimum, maximum transmission speed.

However, single-mode fiber requires the use of high-cost laser (LD) light source transceiver, single-mode fiber laser transceiver at least three times the price of multi-mode fiber optic transceivers, power consumption of at least 2 times.

Traditional multimode fiber typically uses serial transmission mode, in this mode to increase the transmission rate of the Ethernet must increase the fiber / channel per core transmission rate. Ethernet is currently the largest serial transmission rate of 10Gbps / channel, IEEE is developing 25Gbps / channel, 50Gbps / channel network standards to 400G Ethernet, for example, there will be 25Gbps / channel, 50Gbps / 100Gbps channel 3 different versions, The number of optical fiber core need 32 core / 16 core / 8 core respectively. 400G Ethernet encoding used NRZ, PAM4, DMT, more advanced coding means more complex circuits and power consumption, and therefore more costly.

Another way to improve the network transmission rate of multimode fiber is to use parallel transmission mode, that is, by increasing the number of fiber cores to increase the transmission rate. The 2010 release of 100GBase-SR10 using 10Gbps / channel transmission, 10 channels to receive 10-channel transmission, a total of 20 core optical fiber.

In the past practical applications, the choice of multi-mode or single-mode is the most common determinant of distance. If only a few miles, the preferred multimode, because the LED transmitter / receiver than single mode laser is much cheaper. If the distance is greater than 5 miles, the best single-mode fiber. Another issue to consider is bandwidth; if future applications may include the transmission of large bandwidth data signals, then the single-mode will be the best choice.