Wdm Core Network - Transparent Node Architecture

I am doing some research in the field of core WDM networks. And i have no idea how the transceivers/ MUX/DEMUX / OXC etc... components are linked to each other in a core WDM node. Let's consider the simplest node architecture, the transparent node based on optical cross connects. for example, a signal is received by a node from an ingress fiber, the wavelengths should be split via demux, then they enter the OXC and each is routed to the corresponding egress fiber then Muxed with other wavelengths to be sent by a transmitter on the fiber. My question is: -How are the wavelengths connected to the OXC? (Y cards of X wavelengths?) i.e., after the signal is demuxed into separate wavelengths, these latter are sent to cards of X wavelengths each that link the demux to the OXC? Can anybody tell me if it's true? -in the case where my opinion is right, are the cards bidirectionnal? or there are different sorts of cards (ingress and egress to the OXC)? Can anyone please give me a detailed architecture of a node with n>2 nodal degree? (can the OXC switch the same wavelength between links 1 and 2 at the same time as between links 3 and 4? if we imagine that it has more than 4 links connected to the node where it is or do we need different OXCs in the same node in order to switch the same wavelength more than once?) Regards!