Photonics Network

Why is the wavelength-selective ROADM architecture colorless even though it uses AWGs for the multiplexers/demultiplexers rather than WSSs? Consider the broadcast-and-select ROADM architecture at a degree-two node with two add/drop ports. Modify the architecture in order to provide 1:4 protection for the WSSs (i.e., one spare WSS to protect the four primary WSSs).