There is a S-matrix element. Its data is calculated by FDTD. I use two configurations to get the transmission of this element. One is optical power meter, another one is by optical network analyzer.
The problem is the results for two configurations are different. For power meter, the output power is -3.10dB, while for ONA, its transmission is about 0.497524 (-3.03dB). I have no idea where the difference comes. Could anyone help me find it ?