The sensitivity of the optical transceiver module has a critical impact on the performance and transmission distance of the optical communication system. The following will explain its improvement strategy and test method.
In terms of the strategy to improve sensitivity, the first is to optimize the performance of the optical detector. The use of low-noise, high-quantum-efficiency optical detectors, such as avalanche photodiodes (APDs), can enhance the ability to capture weak optical signals. APDs can amplify photocurrents through the internal avalanche multiplication effect, so that they can still effectively detect signals at lower incident light power, reduce the requirements for optical signal strength, and improve the overall sensitivity of the module.
The design of the signal processing circuit is also crucial. A low-noise amplifier is used to amplify the weak electrical signal output by the optical detector to reduce the noise introduced by the signal during the amplification process. At the same time, the use of advanced filtering technology, such as the adaptive filtering algorithm in digital signal processing (DSP), can filter out noise and interference components in the signal, improve the signal-to-noise ratio of the signal, make the signal easier to be accurately identified and processed, and indirectly improve the sensitivity of the optical transceiver module.
Optical design optimization is also indispensable. Precise design and calibration of optical components in optical transceiver modules, such as lenses and fiber couplers, can reduce the loss and scattering of optical signals during transmission. For example, the use of high-precision fiber alignment technology can ensure efficient coupling of optical signals between optical fibers and optoelectronic devices, maximize the transmission of optical signals to optical detectors, increase the optical power at the receiving end, and thus improve sensitivity.
The bit error rate test method is usually used to test the sensitivity of optical transceiver modules. In the test system, an adjustable optical attenuator is set to gradually increase the attenuation of the optical signal, while monitoring the bit error rate of the optical transceiver module receiving signal. When the bit error rate reaches the specified threshold (such as 10⁻⁹ or 10⁻¹²), the optical power at this time is the sensitivity of the module. In this way, the sensitivity performance of the optical transceiver module under different conditions can be accurately evaluated.
Eye diagram testing is also an important means. By observing the opening degree, jitter and other parameters of the eye diagram, the signal quality and sensitivity of the optical transceiver module can be intuitively judged. The larger the eye opening and the smaller the jitter, the better the signal quality and the higher the sensitivity. During the test, the intensity and other parameters of the optical signal can be adjusted, and the sensitivity characteristics of the module can be further analyzed in combination with the changes in the eye diagram.
In addition, the frequency sweep test method can also be used. By scanning the optical signal within a certain frequency range and observing the response characteristics and sensitivity changes of the optical transceiver module at different frequencies, the performance of the module in the entire working frequency band can be fully understood, so as to carry out targeted optimization and improvement.
