First, I would like to clarify your statement about the “usage of passive optical splitters and AWG”. Passive power splitters are always used for TDM, and AWGs – for DWDM. The main difference between TDWM and DWDM is a channels multiplexing technique: time and wavelength for TWDM system on one side and just a wavelength (with dense spacing) for DWDM. TDM is based on Rec. G.707, G.7o3 of ITU-T. WDM is based on Rec. G.694 of ITU-T.