Optical multiplexer and demultiplexer
AssigneeU.S. Philips Corporation
InventorsAntonius J. A. Nicia, Theodorus L. Van Rooy, Jan Haisma
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Abstract
In optical multiplexers and demultiplexers which utilize interference filters and optical gratings losses and noise are reduced by converting the unpolarized light into linearly polarized light. This improves the efficiency of the filters and gratings and suppresses noise which is caused by fluctuations in the degree of polarization of unpolarized light because filters and gratings have different characteristics for the different polarization directions.
Claims7
An optical multiplexer and demultiplexer comprising a first optical fiber for transmitting a pluarlity of light signals of different wavelengths, a plurality of further optical fibers each transmitting a different light signal of at least one of said different wavelengths, wavelength-selective means for directing light of said different wavelengths along a plurality of wavelength-dependent paths between said one fiber and said further fibers, each of said further fibers being associated with a respective one of said paths, means for optically coupling said first and further fibers to said wavelength-selective means, and means arranged between said coupling means and said wavelength-seletive means for converting unpolarized light into substantially linearly polarized light so that light incident on said wavelength selective means is linearly polarized, said converting means comprising means for producing from said unpolarized light two beams of linearly polarized light whose polarization directions are perpendicular to one another and an optical member for rotating the polarization direction of one of the beams through an angle of 90.degree..
Dependencies are inferred from the claim text.