An optical spectral filtering device and associated method for selectively directing
a portion of a wavelength multiplexed input signal, entering through an optical
fiber, into one or more output signals provided to one or more optical fibers and/or
electronic outputs. The optical filtering is accomplished using free-space diffractive
wavelength demultiplexing optics combined with a fixed (permanent) patterned structure
located in the spectrally dispersed image plane. The structure can block or direct
a selected spectral portion of the optical signal to one or more separate outputs,
such as an optical fiber or power detector. A single active element in the optical
path is used to spatially shift, or steer, the entire input spectrum at the dispersed
spectral image plane, to control the portion of the input spectrum illuminating
specific features on the permanent patterned structure.
