Please find enclosed an example of such a WDM optical link. This example has a mix of both 10G and 40G signals entering a multiplexer. The 10G signals are obtained by dividing the bit rate by 4, since the simulation bit rate is set to 40 Gb/s.
There are also more examples of 10 Gb/s or 40 Gb/s systems in the examples folder OptiSystem 12 Samples\WDM Systems. There are also plenty of resources at: