What are the Key Performance Parameters of Optical Modules?

As core optoelectronic conversion devices in high-speed data communication and optical network systems, the performance of optical modules directly affects the stability and transmission efficiency of the entire link. For network equipment manufacturers, system integrators, and operation and maintenance engineers, a deep understanding of the key performance parameters of optical modules is the basis for achieving accurate selection and efficient deployment. This article will systematically analyze the core performance indicators of optical modules from five dimensions: transmit optical power, receive optical power, overload optical power, receiver sensitivity, and extinction ratio.

Transmit Optical Power: Measuring "Light Intensity"

Transmit optical power refers to the optical power output by the light source at the transmitting end of the optical module under normal working conditions, with the unit of dBm. It represents the intensity of the optical signal when it leaves the transmitting end.
If the power is too low, it may cause excessive attenuation of the optical signal during transmission, making it unrecognizable by the receiving end;
If the power is too high, it may cause nonlinear effects and affect transmission quality.
Therefore, transmit optical power is one of the important parameters to measure the output capability of an optical module, and a reasonable choice should be made according to the link length and fiber type.

Receive Optical Power: The "Receivable Range" of the Transmission Link

Receive optical power refers to the range of average optical power that the receiving end of the optical module can receive under the condition of ensuring the bit error rate.
The upper limit is the "overload optical power";
The lower limit is the "receiver sensitivity".
The range of receive optical power determines the ability of the optical module to adapt to signals of different intensities, and is a key parameter for evaluating link availability and fault tolerance.

Overload Optical Power: The "Safety Upper Limit" of the Receiving End

Overload optical power, also known as saturation optical power, refers to the maximum average optical input power that the receiving end component can withstand under specific transmission rate and bit error rate requirements (generally BER=10⁻¹²), with the unit of dBm.
Exceeding this value may cause the receiver to "saturate" or even damage the equipment;
In actual use, the receiving end should be avoided from being exposed to strong light, especially during debugging and hot-swap operations.
Understanding overload optical power helps to avoid unexpected system failures and is an important indicator to ensure the safe operation of the link.

Receiver Sensitivity: The "Recognition Lower Limit" of the Optical Module

Receiver Sensitivity refers to the minimum input average optical power that the receiving end can correctly identify under the premise of ensuring the bit error rate, and it is also expressed in dBm.
A smaller value indicates that the module is more "sensitive", that is, it can receive weaker signals;
However, the higher the rate, the worse the receiver sensitivity usually is.
This parameter is particularly critical for long-distance or long-link transmission and is also an important indicator to examine the receiving capability of the optical module.

Extinction Ratio: The Key to Measuring Signal Quality

Extinction Ratio refers to the ratio of the optical power P1 when the laser transmits all "1" codes to the optical power P0 when it transmits all "0" codes under full modulation conditions, with the unit of dB.
A larger extinction ratio means that the "1" and "0" signals are more distinguishable, and the signal quality is higher;
If the extinction ratio is too low, it may lead to an increase in the bit error rate and affect communication stability.
Therefore, the extinction ratio is an important parameter for measuring the modulation performance and overall output quality of the optical module.

Understanding the key performance parameters of optical modules is not only helpful for equipment selection and network design but also provides a strong technical basis for system operation and maintenance and troubleshooting. In the face of different network architectures and application requirements, only by deeply understanding these core indicators of optical modules can we truly realize a high-performance, low-bit-error, and long-life communication system. If you are purchasing or deploying optical modules, it is recommended to comprehensively consider the transmission distance, network rate, interface device compatibility, and the above performance parameters to ensure the reliability and economy of the networking scheme. For more details, you are welcome to consult the Aoyuan Yichuang technical service team.