Patent ID: 8391709

Claim:
An optical switching device, comprising: a first wavelength selective switch stage comprising: a plurality of input ports, each input port for receiving a respective DWDM signal comprising at least one wavelength channel; a first common port for transmitting at least one of the wavelength channels from one of the respective DWDM signals; a first adjustable reflector for selecting an optical path for a selected one of the respective wavelength channels between one of the plurality of input ports and the first common port; and a first input block port for providing the first adjustable reflector an interim position in which no signal is input to the first common port; wherein the plurality of input ports, the first common port and the first input block port are collinear; a second wavelength selective switch stage comprising: a second common port optically coupled to the first common port for receiving the selected wavelength channel; a plurality of output ports for transmitting the selected wavelength channel; and a second adjustable reflector for selecting an optical path for the selected wavelength channel between the second common port and one of the plurality of output ports; wherein the plurality of output ports and the second common port are collinear; and a switch controller for optically coupling the first input block port and the first common port when the second adjustable reflector is adjusted between settings.