Hi Alessandro.
Thanks for your kind reply. Yes I have tried. In fact I have tried several method to design a gain flattening filter but I seems to have failed. Now, Iam trying to do a gain clamping EDFA by looping as suggested by my SV. Im doing the simulation base on the Journal “A Steady-Gain C-band EDFA for Multi-Wavelength Fiber Optical Transport Networks”. I dont really understand how to use the coupler 50/50. As the splitter, im being told that using 1×2 power splitter is okay.