What Tests Does A High-quality Optical Module Need To Go Through?

With the gradual development of applications such as 5G, AIoT, and cloud computing, there are higher demands for data transmission efficiency. As a core component of optical communication systems, the market size of optical modules has been growing explosively year by year. Currently, the market is flooded with varying quality of optical modules, making it difficult to distinguish high-quality ones. The quality of an optical module determines network transmission performance, and like other high-tech electrical appliances, optical modules undergo rigorous testing and quality control procedures during manufacturing. 

These include optical power testing, sensitivity testing, eye diagram testing, aging testing, real machine testing, and fiber end-face inspection. These processes cover every stage of production to ensure optimal performance. If any procedure fails, the optical module is sent back to the production line for further work.

To ensure product quality, a finished optical module must go through multiple testing steps before shipping:

Eye Diagram Testing and Receiver Sensitivity

Testing Eye diagram testing and adjustment are crucial for ensuring the optimal signal quality of optical modules. An eye diagram, formed by superimposing captured waveforms over three bits using an oscilloscope's persistence function, contains rich information that reflects the overall performance of the optical module. The eye diagram test results reveal the digital signal quality of the optical module. By carefully observing parameters such as eye height, eye width, jitter, and duty cycle, the module's performance can be assessed; a larger eye indicates less inter-symbol interference and better module performance. Additionally, receiver sensitivity testing evaluates the module's ability to receive signals.

Stability Testing

Users of optical modules expect stable performance in all environments. Unstable performance would lead to unreliable network signal transmission. Therefore, various devices or instruments are used to conduct high and low temperature tests and aging tests on optical modules to ensure their stability and reliability.

Compatibility Testing

Since optical modules are used in various devices, each with different models and brands, poor compatibility would prevent them from functioning across different equipment. Compatibility Testing Optical modules are inserted into switches of corresponding brands for testing. Successful communication indicates that the module passes the compatibility test. If communication fails, the module is not compatible with that brand's switch.

Bit Error Rate (BER) and Receiver Sensitivity

Testing BER is a parameter that measures the optical module's ability to correctly transmit bits. It is the ratio of the number of erroneous bits received after optical-to-electrical conversion to the number of bits sent by the error detector within a specified time. BER testing involves using a standard receiver test unit to receive the optical signal output by the module under test, containing pseudo-random signals, and comparing the demodulated signal to complete the BER test.

Wavelength Testing

The optica l modules used at both ends of the communication link must emit at the same wavelength to establish communication. Therefore, manufacturers must test the wavelength of optical modules before shipment to ensure they are within the specified deviation range.

Aging Testing Manufacturers

typically use an optical aging chamber to simulate extreme conditions and test the optical module's performance. After aging testing, the transmission and reception ends must be tested to ensure parameters such as optical power, extinction ratio, and sensitivity meet the requirements.