How to Test the Quality of Optical Transceivers

To ensure its quality and performance, each optical transceiver module must go through rigorous testing and quality inspection before shipment. Procedures include incoming quality control, parameter testing, aging test, etc. All test results must be up to standard, otherwise, the optical module will be returned to the production line for adjustment. In this article we will introduce the testing and inspection procedures that an optical transceiver module will undergo, and how the testing results will affect the quality and performance.

1. Incoming Quality Control and Surface Mounted Component Inspection

Incoming quality control and surface mounted component Inspection are performed prior to assembly. Among them, Incoming quality control means that the manufacturer inspects the quality of incoming components before assembling optical modules, such as detect the Transmitter Optical Sub-assembly (TOSA), Receiver Optical Sub-assembly (ROSA), and Bi-Directional Optical Sub-assembly (BOSA) to ensure the quality of optical modules, reduce the rework rate and defect rate as well as avoid damage to expensive optical equipment. Surface mounted component Inspection mainly checks whether the Printed Circuit Board (PCB) is correct and whether it is contaminated. This ensures the performance of the optical transceiver module.

2. Average Output Power Test

The average output optical power is not only an important parameter of the optical module, but also directly affects the quality of communication

3. Extinction Ratio Test and OMA Test

Extinction ratio is one of the parameters used to measure the quality of optical modules. It is the ratio of light power at high level (i.e. full “1” code) and low level (i.e. full “0” code) of laser output, through the test can detect whether the laser is operating in the best bias point and the best modulation efficiency range. In addition, the optical modulation amplitude (OMA) is also a measure of the power difference between laser on and off.

Both are detected by mainstream optical oscilloscopes. At the same time, in the extinction ratio detection can see the relative amplitude of the light signal “1” level and the “0” level, the larger the extinction ratio, the stronger the relative amplitude, the greater the optical signal can be received and distinguished, and the higher the reception sensitivity. Meanwhile,The extinction ratio is inversely proportional to the optical power, and it can be found that the greater the extinction ratio during the test process, the smaller the emitted optical power.

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