Single-mode And Multi-mode Optical Fiber

1. Transmission distance

2. Transmission rate

3. Cost of use

Light can be the carrier of information. In the optical communication industry, light is the cornerstone of optical communication. We all know that light has different wavelengths, which are divided into visible light and invisible light according to different wavelengths. There are many kinds of light, but in optical communication, we only distinguish single-mode and multi-mode. We use light with a wavelength of about 850nm to 1610nm. These lights are the "couriers" of information.

Single-mode refers to light with a wavelength of 1310nm to 1610nm, and single-mode optical fiber is a general term for optical fibers that transmit light in these bands. Their core diameter is mainly 9um and the cladding diameter is 125um. Optical fiber can only transmit one mode of light and is suitable for long-distance transmission.

Multimode refers to light with a wavelength of 850nm to 1310nm, and multimode optical fiber is also a general term. There are many different options for them. OM1, OM2, OM3, OM4, and OM5 are all multimode optical fibers with a core diameter of 50 or 62.5um and a cladding diameter of 125um. They transmit light of various wavelengths and angles and are suitable for short-distance transmission. In actual use or on-site wiring, we need to make choices based on the following conditions:

1. Transmission distance

For transmission distances above 300m

We will consider using single-mode optical fiber. Single-mode optical fiber is cheap, has low transmission loss and dispersion, can meet the needs of long-distance transmission, and has a large transmission bandwidth, and has no requirements for the module rate.

For transmission distances below 300m

Multimode optical fiber is required. Single-mode optical fiber can also be used, but single-mode lasers are expensive, and multimode lasers are much more affordable. Multimode optical fiber has large transmission loss and dispersion, and cannot meet the requirements of long-distance transmission, but it is no problem to meet short-distance transmission.

2. Transmission rate

Single-mode optical fiber has no requirements for transmission rate. Currently, the most commonly used type is OS2, which can meet the transmission bandwidth requirements of 1G to 1.6T. Multi-mode optical fiber needs to select the corresponding optical fiber type according to the transmission rate. Selecting an inappropriate type will lead to a sharp reduction in the effective transmission distance. Usually, OM1 and OM2 optical fibers are selected for 100M and 1G rates, OM3 optical fibers are selected for 10G and 25G rates, OM4 optical fibers are selected for 40G and above, and OM5 optical fibers are selected for 400G and above.

3. Cost of use

Multi-mode optical fiber is more expensive than single-mode optical fiber, but multi-mode modules are cheaper than single-mode modules. In general, multi-mode optical fiber with multi-mode modules has cost advantages in short distances.