Patent ID: 6993224
Filing Date: 2006-01-31
Classification: G02B

Abstract:
1. An archival waveguide memory device comprising: a large number of elongated waveguides; and a series of segments having predetermined effective indices of refraction (neff) distributed within each of said waveguides in accordance with data to be stored within said waveguides so as to act upon an input optical signal in each one of said waveguides and to generate a reflected output optical signal able to be uniquely correlated with said data; wherein said segments modify a transverse dimension of said elongated waveguide in abrupt steps, said abrupt steps corresponding to a change in the waveguide transverse dimension occurring along said waveguide in less than one tenth of a wavelength of light in a medium of the waveguide, said abrupt steps defining a plurality of spatially interleaved subsets of sharp optically reflecting interfaces, each one of said subsets having said sharp interfaces placed according to a positioning pattern along the waveguide with an accuracy better than one hundredth of a wavelength in terms of the optical path lengths between interfaces belonging to the same subset, in order to coherently reflect light according to a desired optical spectrum, said spectrum of reflected light occupying spectral regions substantially distinct from the spectral regions where other subsets of said sharp interfaces reflect light, wherein said segments are designed for single transverse mode operation over a full spectral range of interest, wherein a reflected filtered output optical signal is generated, wherein the transverse waveguide dimension varies within a range sufficiently narrow that a mode size remains close to its minimum size and does not deviate by more than five percent over said minimum size for the full optical spectrum.