Patent ID: 7177498

Claim:
A two-by-two optical routing element for receiving, at each of a pair of input ports, light having a plurality of spectral bands, and directing selected ones of the spectral bands to either of two output ports, the two-by-two optical routing element, comprising: a free-space optical train disposed between the input ports and the output ports providing optical paths for routing the spectral bands, the optical train having a dispersive element disposed to intercept the light traveling from the input port; and a routing mechanism having a plurality of dynamically configurable retroreflecting elements, each such dynamically configurable retroreflecting element including: a first reflective surface inclined with respect to an axis; and a second reflective surface opposed to the first surface, thereby forming an included angle α; wherein the first reflective surface and the second reflective surface are configured for rotation together about the axis to a plurality of positions including at least a first position, a second position, and a third position; wherein the surfaces are disposed such that when the surfaces are in the first position, a first ray is retroreflected along a first path, thereby directing a first spectral band toward a first one of the output ports, and when the surfaces are in the second position, the first ray is retroreflected along a second path, thereby directing the first spectral band toward a second one of the output ports; wherein the surfaces are further disposed such that when the surfaces are in the first position, a second ray is retroreflected along the second path, thereby directing a second spectral band toward the second one of the output ports, and when the surfaces are in the second position, the second ray is retroreflected along the first path, thereby directing the second spectral band toward the first one of the output ports; and wherein the surfaces are further disposed such that when the surfaces are in the third position, the first spectral band and the second spectral band are directed away from an output port.