What is the difference between SM and MM fiber optic transceiver?

First of all, what is fiber optic transceiver? The fiber optic transceiver is composed of optoelectronic devices, functional circuits and optical interfaces. The optoelectronic device includes transmitting and receiving parts. The function of the fiber optic transceiver is photoelectric conversion. The transmitting end converts electrical signals into optical signals. After transmission through optical fibers, the receiving end converts the optical signals into electrical signals. Fiber optic transceivers are widely used in fiber media converter, server network cards, switches, routers, and wireless base station equipment.

Regarding the difference between single-mode(SM) and multi-mode(MM) fiber optic transceivers, the products produced by different fiber optic transceiver manufacturers may be slightly different, but the main differences are in the following aspects:

1. Fiber Type

Fiber optic transceiver can be divided into single-mode (SM) fiber optic transceiver and multi-mode (MM) fiber optic transceiver according to fiber types.The single-mode optical fiber SMF fiber diameter of 9 / 125μm and multi-mode fiber MMF fiber diameter of generally 50 / 125μm or 62.5 / 125μm. Single-mode fiber optic transceivers are suitable for long-distance transmission, and optical fibers are generally yellow; and Multi-module fiber optic transceivers are suitable for short-distance transmission, and optical fibers are generally orange.

2. Wavelength

The working wavelength of a multi-mode fiber optic transceiver is generally 850nm, which is mostly used in short-distance transmission, with a transmission distance below 2km. The working wavelengths of single-mode fiber optic transceiver is generally 1310nm and 1550nm, which is often used for long-distance transmission, and the transmission distance can reach 150 to 200km. The wavelength can also be distinguished directly from the color of the pull ring. For example, the black pull ring is multi-mode and the wavelength is 850nm; the blue pull ring is a transceiver with a wavelength of 1310nm; yellow or green is a transceiver with a wavelength of 1550nm; purple is a wavelength 1490nm transceiver, etc.

3. Light Source

The light source is a single-mode fiber optic transceiver LD or narrow spectral line LED, the light source is a multi-mode fiber optic transceiver a light emitting diode or a laser.

4. Applications

Multi-mode fiber optic transceiver is mostly used in networks with relatively low transmission rates and relatively short transmission distances, such as local area networks. This type of network usually has many nodes, many joints, many bends, and the amount of connectors and couplers is large. The length uses the characteristics of a large number of light sources, and the use of multi-mode optical fibers can effectively reduce network costs. Single-mode fiber optic transceiver is mostly used in lines with long transmission distances and relatively high transmission rates, such as long-distance trunk transmission and metropolitan area network construction.

Precautions for using SM fiber optic transceiver and MM fiber optic transceiver

  1. MM fiber optic transceiver cannot be transmitted on SM fiber, and are limited to run on MM fiber.
  2. SM fiber optic transceiver with a transmission distance of 10km can be transmitted on a MM fiber, and the transmission distance is the same as that of the corresponding MM fiber optic transceiver on a MM fiber. The main factor affecting the transmission distance is dispersion rather than attenuation coefficient.
  3. The receiving power must have a margin, and the optical power of the receiving end cannot exceed the saturated optical power value, otherwise the receiving device may be damaged.
Fiber optic transceiverMm fiberSm fiber

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