I have a similar problem about optical subtractor in optisystem 15:
Only having the same wavelength and same power, the two input optical signal can be correct subtracted(=0).If not, the output signal seems to be the add result of two input signals.
finally, I want to known the version of “Optical Subtractor.osd” you provided. and there is a .osd about version 13 or 15.
thanks!