Singlemode and Multimode Fiber Optic Transceivers

Which is more advanced, single-mode or multi-mode technology? Single-mode fiber is used for long-distance transmission, and multimode fiber is used for indoor data transmission. Only single-mode can be used for long-distance, and multi-mode is not necessarily used for indoor data transmission.

Is the optical fiber used in servers and storage devices single-mode or multi-mode?

Does the optical fiber have to be used in pairs, and is there any equipment such as a single-hole single-mode optical fiber signal converter?

Do fibers have to be used in pairs? Yes, the second half of the question, do you mean transmit and receive light on one fiber? This is possible. China Telecom's 1600G backbone optical fiber network is like this.

The most fundamental difference between single-mode fiber optic transceivers and multimode fiber optic transceivers is the transmission distance. The multi-mode optical fiber transceiver is multi-node multi-port signal transmission in the working mode, so the signal transmission distance is relatively short, but it is more convenient, and does not need to use the construction of the local intranet. Single fiber is single-node transmission, suitable for long-distance trunk lines Transmission constitutes the construction of a cross-city area network. In terms of price, single-mode is more expensive than multi-mode.

Single-mode fiber optic transceiver: transmission distance from 20km to 120km

Multimode fiber optic transceiver: transmission distance from 2km to 5km

Single Fiber Transceiver: Receive and transmit data on one fiber

Dual Fiber Transceiver: Receives and transmits data on a pair of fibers

According to the transmission mode of light in the optical fiber, it can be divided into: single-mode optical fiber and multi-mode optical fiber

1. um=1 micron=0.001 millimeter

The core diameter of the multimode fiber is 50~62.5 μm, the outer diameter of the cladding is 125 μm, the core diameter of the single mode fiber is 8.3 μm, and the outer diameter of the cladding is 125 μm. The working wavelength of the optical fiber is 0.85 μm for short wavelength, and 1.31 μm and 1.55 μm for long wavelength. Fiber loss generally decreases with increasing wavelength. The loss of 0.85μm is 2.5dB/km, the loss of 1.31μm is 0.35dB/km, and the loss of 1.55μm is 0.20dB/km, which is the minimum loss of optical fiber. The loss μm above 1.65 wavelength tends to increase. Due to the absorption of OHˉ, there are loss peaks in the range of 0.90~1.30μm and 1.34~1.52μm, which have not been fully utilized. Since the 1980s, the use of single-mode fiber has tended to increase, and the long wavelength of 1.31 μm was first used.

2. Multimode fiber

Multimode fiber: The central glass core is thicker (50 or 62.5 μm) and can transmit light in multiple modes. However, its intermodal dispersion is large, which limits the frequency of digital signal transmission, and it will be more serious as the distance increases. For example: 600MB/KM optical fiber has only 300MB bandwidth at 2KM. Therefore, the transmission distance of multimode fiber is relatively short, generally only a few kilometers.

3. Single-mode fiber

Single Mode Fiber (Single Mode Fiber): The central glass core is very thin (core diameter is generally 9 or 10 μm), and can only transmit light of one mode. Therefore, its intermodal dispersion is very small, suitable for long-distance communication, but there are also material dispersion and waveguide dispersion, so single-mode fiber has higher requirements on the spectral width and stability of the light source, that is, the spectral width should be narrow and wide Stablize. be good. It was later found that at a wavelength of 1.31 μm, the material dispersion and waveguide dispersion of a single-mode fiber are positive and negative, and the magnitudes are exactly the same. This means that at a wavelength of 1.31 μm, the total dispersion of single-mode fiber is zero. From the point of view of the loss characteristics of the fiber, 1.31 μm is just a low loss window of the fiber. In this way, the 1.31 μm wavelength region becomes the ideal working window for optical fiber communication, and it is also the main working band of the actual optical fiber communication system. The main parameters of 1.31μm conventional single-mode fiber are determined by the International Telecommunication Union ITU-T in the G652 recommendation, so this fiber is also called G652 fiber.