Patent ID: 7738750

Claim:
An optical wavelength multiplexer/demultiplexer, comprising: a planar first filter element; a planar second filter element offset from the first filter element in a first direction to receive light reflected and transmitted from a first location on the first filter element, the second filter element and the first filter element having orthogonal surface normals; and a planar reflector parallel to the second filter element and offset therefrom in a second direction to receive light reflected and transmitted from a second location on the first filter element, the second direction orthogonal to the first direction, the second location offset from the first location in the second direction; in which; each of the filter elements is configured to transmit light and to reflect light in respective non-overlapping wavelength ranges; and one of the first filter clement and the second filter element has one of (a) a band-pass transmission characteristic, and (b) a band-stop transmission characteristic.