First of all you have to shutdown all the wave interfaces except one of them, let's say wave9/0/0 would be no sh. Then you can measure this particular lambda with regular optical power meter and check what is the optical power level at Trunk-In interface on MUX/DMUX card. By this we will make sure if we've got good incoming signal at DMUX. Here is the diagram of how to measure the optical power level coming out of the fiber:

15540<--x (power-meter) <----//fiber_20dB//-------<---[Trunk-Out]15540 Fiber-optic transmission specifications identify two types of fiber: single-mode and multimode. Signals can travel farther through single-mode fiber than through multimode fiber. The maximum distance for single-mode installations is determined by the amount of light loss in the fiber path. For more information please click following URL:

http://www.cisco.com/en/US/products/ps6342/prod_module_installation_guide09186a008048ca40.html#wp574697