Optical modules have many important photoelectric technical parameters, and for most of us, it is not easy to understand optical modules in depth. For example, SFP optical modules and SFP+ optical modules look very similar in appearance, and most switches support both SFP modules and SFP+ modules. So are they really the same kind of module? What's the difference between them?
First of all, we need to understand the various parameters of optical modules, among which there are three main types (central wavelength, transmission distance and transmission rate). The main differences between optical modules are also reflected in these points.
Central wavelength
The unit of central wavelength is nanometer (nm). Currently, there are mainly three types:
1) 850nm (MM, multi-mode, low cost but short transmission distance, generally only 500m);
2) 1310nm (SM, single mode, high loss but small dispersion in the transmission process, generally used for transmission within 40km);
3) 1550nm (SM, single mode, with small loss but large dispersion in the transmission process, is generally used for long-distance transmission over 40km, and the longest transmission can be directly 120km).
Transmission distance
Transmission distance refers to the distance that an optical signal can be transmitted directly without intermediate amplification, which is per kilometer (also known as kilometer, km). Optical modules generally have the following specifications: multi-mode 550m, single mode 15km, 40km, 80km and 120km, etc.
Transmission rate
Transmission rate refers to the number of bits (BPS) of data transmitted per second. Transmission rates as low as 100 megabits and as high as 100Gbps are commonly used at 155Mbps, 1.25Gbps, 2.5Gbps and 10Gbps. Transmission rates are generally downward, and in addition, optical modules in optical fiber storage systems (sans) have three rates: 2Gbps, 4Gbps, and 8Gbps.
Understand the above three light module parameters, we have a preliminary understanding of the light module, want to further cognition, then to see the light module of other parameters.
