Last Updated on January 16, 2023 by Umer Malik

As we all know, optical transceiver is an important part of an optical fiber communication network. Usually, everyone is very concerned about the performance of Ethernet switches. However, they may ignore the quality of the important components-‚Äčoptical modules, and the price has become the only factor for purchase. But the fact is that the market is now flooded with low-quality optical modules, and it is difficult for ordinary users to distinguish between high-quality optical modules.

The quality of the optical module determines the network transmission performance, which can be significantly reduced once it is off. Like other high-tech electrical appliances, optical modules undergo strict testing and quality inspection procedures during the manufacturing process, such as optical power testing, sensitivity testing, eye pattern testing, burn-in testing, real machine testing, fiber end face testing, etc. These processes involve Every stage of the production process to ensure the best results. If any procedure fails, the optical module is rejected and returned to the production line to do the heavy lifting.

So how to test the performance parameters of the optical module?

Fiber Optic Transceivers

Optical Module Average Output Optical Power Measurement

The transmit port of the optical transceiver consists of a light source and related electronic circuits. Semiconductor-based light-emitting diodes (LEDs) and laser diodes are used as light sources in phototransistors. LEDs and Vertical Cavity Surface Emitting Lasers (VCSELs) are typically used for transmitters on local and local networks, while Fabry-Perot (FP) lasers and Distributed Feedback (DFB) lasers are used in Metro and Long-haul networks’ transmitters.

In optical communications, the light source is intensity modulated, a process in which different currents are applied to the laser to vary the output power level. The limited power level represents a logical zero, rather than an actual, complete absence of power.

The average output optical power is an important parameter of the transmitter, which directly affects the communication quality of the module. It is the average optical power of the receiver under normal operating conditions. The optical power meter can measure the average output optical power to test the optical power at the transmission end. For transmitters that transmit over long distances, the average optical power is greater than the maximum input optical power.

Average optical power is measured with an optical power meter. The unit of measurement is usually expressed in dBm, which is the logarithmic ratio of power level to 1mW.

Optical Module Extinction Ratio Measurement

When used to describe the performance of an optical transmitter used in digital communications, the extinction ratio is simply the ratio of the energy (power) used to transmit a logic level ‘1’ to the energy used to transmit a logic level ‘0’. For graphical descriptions, eye diagrams are often used. Optical modulation amplitude measurement

Optical Modulation Amplitude (OMA) is used to measure the difference between two optical power levels produced by a power supply, such as P1 (when the light source is on) and P0 (when the light source is off). With OMA, low or high dimming ratios can be used, provided the transmitter is eye safe and does not overload the receiver.

Optical modulation amplitude measurement

Optical Modulation Amplitude (OMA) is used to measure the difference between two optical power levels produced by a power supply, such as P1 (when the light source is on) and P0 (when the light source is off). With OMA, low or high dimming ratios can be used, provided the transmitter is eye safe and does not overload the receiver.

Optical Module Compatibility Test

Compatibility testing is mainly for compatible optical modules. Plug the optical module into the switch of the corresponding brand of equipment to test. If the communication is normal, the optical module passes the test. If it cannot communicate, it means that the optical module is not compatible.

Visual inspection

It involves inspecting optical modules for quality control before shipment. Check the case of each module for scratches, dirt, color, smoothness, gold finger scratches and labels. Usually, the appearance of the optical module is not good and there are defects, but the appearance of the high-quality optical module is good.

Conclusion

This article introduces what tests a high-quality optical module needs to pass, and the meaning of these test links and parameters. Through reading, I hope you can quickly distinguish whether an optical module is good or bad. Be sure to choose a high-quality optical module that determines the stability and transmission quality of your network. QSFPTEK provides high-quality a full series of SFP+, QSFP28, QSFP+, QSFP28 transceivers, welcome to consult via sales@qsfptek.com.

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