Do You Understand Single-mode and Multi-mode Fiber Optic Transceivers?

Optical fiber transceivers are widely used in long-distance transmission and can solve practical problems in many projects. It is necessary to be familiar with its use. Next, let's learn more about the difference between single-mode and multi-mode fiber optic transceivers, and how to quickly distinguish between single-mode and multi-mode fibers.

Ⅰ. Fiber optic transceivers can be divided into: single-mode fiber and multi-mode fiber

1. Single-mode fiber

The central glass core of the single-mode optical fiber transceiver is very thin, the core diameter is generally 9 or 10 μm, and only one mode of light can be transmitted. Therefore, its intermodal dispersion is very small, which is suitable for long-distance communication, but there are also material dispersion and waveguide dispersion, so that the single-mode fiber has a higher spectral width (measurement of the wavelength range of the spectrum or spectral characteristics) and stability of the light source. The requirements, that is, the spectral width should be narrow and the stability should be good. At the wavelength of 1.31 μm, the material dispersion and waveguide dispersion of the single-mode fiber are positive and negative, and the magnitudes are exactly equal. This means that at a wavelength of 1.31 μm, the total dispersion of the single-mode fiber is zero. From the loss characteristics of optical fiber, 1.31μm is just a low-loss window of optical fiber. In this way, the wavelength region of 1.31μm has become an ideal working window for optical fiber communication, and it is also the main working band of optical fiber communication systems.

2. Multimode fiber

The central glass core of the multimode optical fiber is relatively thick, generally 50 or 62.5 μm, and can transmit multiple modes of light. However, its intermodal dispersion is relatively large, which limits the frequency of digital signal transmission, and it will be more serious with the increase of distance.

Ⅱ. The method of distinguishing whether the fiber optic transceiver is single-mode or multi-mode

1. Functional distinction

The most fundamental difference between single-mode fiber optic transceivers and multimode fiber optic transceivers is the transmission distance. The transmission distance of single-mode fiber optic transceivers is 20 kilometers to 120 kilometers, and the transmission distance of multimode fiber optic transceivers is 2 kilometers to 5 kilometers.

The single-mode fiber optic transceiver is a single-node transmission, so it is suitable for long-distance trunk transmission and the construction of a cross-city LAN. In terms of price, single-mode fiber optic transceivers are more expensive than multi-mode ones; The above is a multi-node, multi-port signal transmission, so the signal transmission distance is relatively short, but it is more convenient, and the construction of a local area intranet is mostly used.

2. Distinguish from the appearance

(1) Identify from the optical head: unplug the optical fiber transceiver optical head dust cap, look at the color of the interface device inside the optical head, the inner side of the single-mode TX and RX interface is coated with white ceramics, and the multi-mode interface is brown.

(2) Distinguish from the model: Generally, it depends on whether there are S and M in the model, S means single-mode, and M means multi-mode.

(3) If it has been installed and used, you can see the color of the optical fiber jumper. Orange is multimode and yellow is singlemode.

A single-mode transceiver can work on both single-mode fiber and multi-mode fiber, while a multi-mode fiber transceiver cannot work on single-mode fiber. In addition, there are single-multimode converter devices on the market. It can solve the interchange of single-mode fiber and multi-mode fiber.