1. Optical Power Detection
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The average output optical power is an important parameter of the SFP+ optical module, which directly affects the communication quality.
2. Extinction Ratio and Optical Modulation Amplitude (OMA) Test
The extinction ratio is one of the parameters used to measure the quality of the SFP+ optical module. The extinction ratio refers to the ratio of the optical power of the high level (that is, all “1” codes) and low level (that is, all “0” codes) output by the laser. The test detects whether the laser is operating within the optimal bias point and optimal modulation efficiency. In addition, the optical modulation amplitude (OMA) is also a measure of the difference in power between when the laser is turned on and off.
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Both are detected by mainstream optical oscilloscopes. At the same time, the relative amplitude of the “1” level and the “0” level of the optical signal can be seen in the extinction ratio detection. The sensitivity will be higher. At the same time, the extinction ratio is inversely proportional to the optical power. During the test, it can be found that the larger the extinction ratio, the smaller the emitted optical power.
3. Bit Error Rate and Receiving Sensitivity Test
The bit error rate is one of the parameters to measure the ability of an optical module to transmit symbols correctly. The bit error rate refers to the ratio of the number of error symbols received after the photoelectric conversion at the receiving end within a specified time to the number of symbols given by the output end of the error meter. The bit error rate test needs to receive the optical signal with pseudo-random signal output by the tested SFP+ optical module through the standard receiving tube test unit, and at the same time use the standard receiving tube test unit to demodulate and compare to complete the bit error rate test.
4. Wavelength Test
Since the SFP+ optical modules used on the devices at both ends must transmit the same wavelength to establish communication, the manufacturer must test the wavelength of the SFP+ optical module before shipment to ensure that it is within the deviation range. Generally, manufacturers will use instruments such as spectrum analyzers to measure the central wavelength of the SFP+ optical module, and the measured central wavelength value of the SFP+ optical module usually deviates from the standard value. The deviation of different types of SFP+ optical modules is different, but as long as the deviation is within the allowable range If the tested value is inconsistent with the standard specification, the SFP+ optical module is regarded as a defective product.
5. Aging Detection
Manufacturers generally use a light aging box to simulate extreme conditions to test the SFP+ optical module to verify whether the performance of the SFP+ optical module meets the standard. After the aging test is completed, the transmitter and receiver need to be tested, mainly to check whether the parameters such as optical power, extinction ratio, and sensitivity meet the requirements.
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6. Compatibility Test
Insert the SFP+ optical module into the switch of the corresponding brand for testing. If the communication is normal, the SFP+ optical module passes the test. If it cannot communicate, it means that the SFP+ optical module is not compatible with it.
7. End Face Detection
After each test item of the SFP+ optical module, it is necessary to inspect the end face of the module for dirt and scratches through a microscope. If there is dirt, it needs to be cleaned.
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