PRIMUS IT Limited.
PRIMUS IT Limited.

Introduction to the Basic Knowledge of Optical Modules

Many users have a certain understanding of switches, but when it comes to optical modules, many users don't know much about it. Optical modules are mainly used for transmission between switches and devices, and are more efficient and safer than transceivers. The optical module is a very important transmission carrier for the switch, so what is the optical module and why can it play such a big role in the switch? Here, Primus IT will introduce the basic knowledge about optical modules.

Ⅰ. Optical modules are generally used in the backbone network of optical fiber networks

Optical modules are mainly divided into GBIC, SFP, SFP+, XFP, SFF, CFP, etc., and optical interface types include SC and LC. However, SFP optical modules, SFP+ optical modules, and XFP optical modules are commonly used nowadays instead of GBIC. The reason is that GBIC is bulky and easily broken. However, the commonly used SFP optical module is small and cheap. Divided by type, optical modules can be divided into single-mode optical modules and multi-mode optical modules. Single-mode optical modules are suitable for long-distance transmission; multi-mode optical modules are suitable for short-distance transmission.

Ⅱ. The development direction of optical modules and optical devices

Optical devices in optical modules are developing towards miniaturization, improving (electrical/optical, optical/electrical conversion) efficiency, and improving reliability. Planar optical waveguide (PLC) technology will further reduce the volume of two-way/three-way optical components and improve component reliability. The functions and performance of integrated circuit chips have been strengthened, so that the volume of optical modules has been reduced and the performance has been continuously improved. The system continuously puts forward new requirements for the additional functions of the module, and the intelligent function of the optical module must be continuously improved to meet the needs of the system.

Ⅲ. In the switch, the importance of the optical module far exceeds the core chip

1. The optical module is composed of optoelectronic devices, functional circuits and optical interfaces. Simply put, the role of the optical module is photoelectric conversion. The transmitting end converts the telecom ftth signal into an optical signal. After transmission through the optical fiber, the receiving end converts the optical signal into an electrical signal. Compared with transceivers, it is more efficient and safer. After the power is turned on, the optical module is in the continuous light-emitting process, and it will inevitably attenuate after a long time. Therefore, the work of detecting the optical module is very important.

2. We need to use an optical power meter to detect the optical module. Generally, when the optical module leaves the factory, the original manufacturer will hand over the quality inspection report of this batch to the processing manufacturer. The manufacturer uses an optical power meter for actual evaluation, and when the difference is within the reported range, it is a qualified product.

3. For the optical module to be tested, the factory power range is -3~8dBm. Through numerical comparison, the optical module can be determined as a qualified product. It should be noted that the smaller the power value, the weaker its optical communication capability. In other words, low-power optical modules cannot carry out long-distance transmission. According to relevant sources in the industry, some small workshops will buy second-hand optical modules, whose numbers are refurbished and used in short-distance optical transmission equipment. Obviously, this is extremely irresponsible to users.