Knowledge of long-distance optical modules

Optical modules are the most common photoelectric conversion devices. In the optical communication network, the transmission capacity is the most important and the most concerned parameter. Among them, the transmission distances of the optical modules are also different. In different fields and links of optical communication network transmission, the characteristics of optical modules are also different. In this issue, I will take you to understand the long-distance optical module.

1. Transmission distance and application of long-distance modules

Transmission distance is one of the important factors of optical modules, and optical modules are also divided into short-distance optical modules, medium-distance optical modules and long-distance optical modules. Short-distance optical modules support link lengths of 2km and below, medium-distance optical modules support link lengths of 10-20km, and long-distance optical modules support link lengths of 40km and above. The transmitting optical power of the transmitting end, the receiving sensitivity of the receiving end and the optical attenuation coefficient are the three factors of the optical transmission distance.

The transmission distance of the optical module is not as far as possible, and appropriate solutions should be adopted in due course. Long-distance optical modules are mainly used in metropolitan area network, optical synchronous digital transmission network, Ethernet, Fibre Channel, synchronous digital system, synchronous optical fiber network, telecommunications and other fields.

2. What types of long-distance optical modules are there?

There are long-distance optical modules in the optical module types of SFP, SFP+, SFP28, QSFP+ and QSFP28. Among them, the common long-distance optical module specifications are 40km, 80KM, 120KM and so on.

3. Precautions for the use of long-distance optical modules

Since long-distance optical modules have strict requirements on the received optical power range, if the receiving sensitivity is exceeded, it is easy to cause damage to the optical module. In order to reduce the failure of long-distance optical modules caused by improper use, the following precautions should be taken when using:

(1) Test the optical power of the receiving end before connecting. If the optical power is too strong, consider using an appropriate attenuator to add additional attenuation to meet the connection requirements.

(2) When a single-mode optical module with a transmission distance of more than 10km is transmitting, the optical power at the receiving end cannot exceed the saturated optical power value.

(3) Long-distance optical modules can be completely attenuated in 10km link applications. Generally, modules longer than 40km need to be attenuated and cannot be directly connected, otherwise the transmitting and receiving components will be easily damaged.