Eye diagram testing and adjustment is an important stage to ensure that the optical module obtains the best signal.
The so-called eye diagram is formed by superimposing and accumulating all captured waveforms every three bits through the afterglow function of the oscilloscope.
The digital signal quality of the optical module can be seen from the eye diagram test results. By carefully observing the eye height, Eye width, jitter, duty cycle, etc. are used to judge the performance of the optical module. The larger the eye, the smaller the crosstalk between codes and the better the performance of the optical module.
In addition, in the multi-source agreement (MSA), the standard eye diagram of the optical module (that is, the eye diagram composed of purple in the figure below) is clearly specified. After the eye diagram test of the optical module, observe whether the eye diagram has contact with the standard eye diagram.
If there is no contact, the indicator of the eye diagram meets the standard, but if the tested eye diagram exceeds the standard eye diagram, the optical module cannot pass the test and additional calibration must be performed, and targeted improvements can be made according to the contact position.
This is a video of HTF technician doing eye diagram
