We demonstrate a technique of evaluating optical signal to noise ratio (OSNR) associated with an optical carrier in a fiber-optic system using a commercial coherent optical transceiver equipped with digital signal processing capability. The procedure of measuring noises caused by the transmitter and the receiver is outlined, and these transceiver-related noises need to be taken into account in order to accurately evaluate the system OSNR. Through digital polarization-demultiplexing and polarization nulling in the receiver, it is possible to extract the noise underneath the optical signal, and to measure the tilt of the ASE noise spectrum within the optical signal bandwidth.

中文翻译：

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使用数字相干收发器估算系统 OSNR

我们展示了一种评估与光纤系统中的光载波相关的光信噪比 (OSNR) 的技术，该技术使用配备数字信号处理能力的商用相干光收发器。概述了测量由发射器和接收器引起的噪声的过程，需要考虑这些与收发器相关的噪声，以便准确评估系统 OSNR。通过接收器中的数字偏振解复用和偏振归零，可以提取光信号下方的噪声，并测量光信号带宽内 ASE 噪声频谱的倾斜度。