What should a high-quality optical module have?

What conditions do high-quality optical transceivers need to have 

As shown in the figure above, the optical module is composed of optical devices, functional circuits and optical interface components, etc., of which the core components are optical transceiver devices, mainly including TOSA, ROSA and BOSA. 

Transmitter Optical Subassembly: lasers, metal structural parts and ceramic inserts, etc.

Receiver Optical Subassembly :P IN or APD detectors, preamplifiers and other structural parts. 

Biodirector Optical Subassembly: Lasers, detectors, optical filters, metal parts, ceramic sleeves and inserts. 

See the various components of the optical module, Presumably everyone can also know that although the standard of the optical module is unified, the optical module of different manufacturers, according to the different materials selected, there are huge differences in the quality of their products. For example, the quality of the PCB, the quality of the capacitor resistance inductor, the thickness of the gold finger, the quality of the solder, and even the choice of glue in it can affect the quality of the optical module. For example, the temperature of the optical module rises when it is used, and it cannot dissipate heat, which will affect its performance. 

Of course, the performance of lasers from different manufacturers will also vary, some receive high sensitivity, some low points, which is why many people find that the optical module is insufficient in the transmission distance when it is actually used (of course, it also needs to look at the light decay of the actual line). 

In addition to the choice of product materials, the test of optical modules also makes the optical module uneven in quality. High-quality optical transceivers must pass the following tests. 

1、 Average output optical power test 

Average output power is an important parameter of the optical module, which directly affects the quality of communication. 

2、Extinction ratio and light modulation amplitude (OMA) test 

Extinction ratio is one of the parameters used to measure the quality of optical modules. Extinction ratio refers to the ratio of the time power of the laser output at high level (i.e., full "1" code) and low level (i.e., full "0" code), and the test detects whether the laser is operating within the optimal bias point and the best modulation efficiency range. In addition, the light modulation amplitude (OMA) is also a measure of the power difference between the laser when it is turned on and off. The larger the extinction ratio, the stronger the ability of the optical signal to be received and distinguished, and the higher the reception sensitivity. 

3、Bit error rate test 

Bit error rate is one of the parameters that measure the ability of the optical module to correctly transmit the code element. The bit error rate refers to the ratio of the number of bit error elements received after the photoelectric conversion at the receiving end within a specified time to the number of code elements given by the output of the code error meter. 

4、Eye diagram test 

Eye diagram test and adjustment is an important stage to ensure that the optical module obtains the best signal. From the eye diagram test results can be seen in the optical module digital signal quality, by carefully observing the eye height, eye width, jitter, duty cycle, etc. of the eye diagram to judge the performance of the optical module, the larger the eye indicates that the smaller the crosstalk between the codes, the better the performance of the optical module. 

5、Wavelength test 

6、Aging test 

7、Real machine compatibility test.What conditions do high-quality optical transceivers need to have