In this article, we will analyze the types of common optical modules to facilitate the understanding of their unique properties by their names and classifications.

1. Classification by rate

In order to meet the requirements of various transmission rates, optical modules with different rates are produced: 400GE optical modules, 100GE optical modules, 40GE optical modules, 25GE optical modules, 10GE optical modules, GE optical modules, FE optical modules, etc.

2. Classification according to package type

The higher the transmission rate, the more complex the structure, resulting in different packaging methods. The following package types are available for switches: QSFP-DD, QSFP28, QSFP+, SFP28, SFP/eSFP, SFP+, CXP, and CFP.

3. Classification by mode

Optical fibers are divided into single-mode optical fibers and multi-mode optical fibers. In order to use different types of optical fibers, single-mode optical modules and multi-mode optical modules have been produced.

· The center wavelength of a single-mode optical module is generally 1310nm and 1550nm, which is used in conjunction with single-mode optical fiber. Single-mode optical fiber transmission frequency bandwidth, large transmission capacity, suitable for long-distance transmission.

· The center wavelength of multimode optical modules is generally 850nm, which is used in conjunction with multimode optical fibers. Multimode fiber has pattern dispersion defects, and its transmission performance is worse than that of single-mode fiber, but the cost is low, and it is suitable for small-capacity, short-distance transmission.

When using long-distance optical modules, the transmitting optical power is generally greater than the overload optical power, so it is necessary to pay attention to the length of the optical fiber to ensure that the actual received optical power is less than the overload optical power. If the length of the optical fiber is short, you need to use the optical attenuation (the attenuation value per unit length of the optical fiber, measured in dB/km) to avoid burning out the counter-optical module.

4. classified by the center wavelength

The operating wavelength of the optical module is a range, and the unit is nanometers (nm) for the purpose of describing the parameter using the center wavelength.

In order to support the transmission of optical signals, different optical bands are used, and optical modules with different center wavelengths are produced, such as 850nm, 1310nm, 1550nm, etc.

5. Classification by color

The biggest difference between color optical modules and other types of optical modules is that the center wavelength is different:

1. Generally, the center wavelength of the optical module is 850nm, 1310nm and 1550nm, and the center wavelength is relatively single, we call this type of light "black and white light" or "gray light".

2. The color light module carries a number of different center wavelengths of light, so the intersection is colorful, we call this kind of light "color light".

There are two types of color optical modules: coarse set wave optical module (CWDM) and dense wave optical module (DWDM). In the same band, there are more types of dense wave optical modules, so the dense wave optical module makes more full use of the resources of the band. Therefore, the light with different center wavelengths from multiple color optical modules is synthesized and transmitted by a passive combiner, and the far end is separated into multiple channels according to different center wavelengths through a splitter, which effectively saves the optical fiber line. Color optical modules are mainly used in long-distance transmission lines.

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