Hi aabid and aasif, thank for your comment as i said i try to do analyse Performance on single channel transmission of ng pon2 with some impairment: antenuation, Cd, non linear,…base on my attached file, in my attached file, they use 40gb upstream( 4 pair wavelenght 10gbps) and 10gb downstreem. But i still want to build a TWDM 10gbps upstream(4×2.5gbps) and 2.5 gbps downstream, in addition, i dont know how to use optisystem to show diagram same figure 27 in my attached file.