Optical fiber non-reciprocal phase shifters and optical isolators using them
AssigneeAT&T Corp.
InventorsDavid J. DiGiovanni, Kenneth L. Walker, Weyl-Kuo Wang, Raymond Wolfe
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Abstract
In accordance with the invention, an optical fiber phase shifter comprises a length of asymmetrical optical fiber disposed perpendicular to a magnetic field for providing a non-reciprocal phase shift. Preferably the fiber is wound in a circular coil and exposed to an axial field as from a pancake magnet. In an isolator, the fiber length and magnet strength are chosen to provide non-reciprocal phase shifts of .+-.45.degree. or .+-.90.degree.. The isolator including the phase shifter can be any of several configurations.
Claims11
An optical fiber non-reciprocal phase shifting device comprising:
- a length of optical fiber having a core and a cladding and a longitudinal direction for light propagation;
- a magnet for applying a magnetic field to said optical fiber in a direction transverse to said longitudinal direction;
- said longitudinal direction and the direction of said magnetic field defining a plane;
- and
- said core being asymmetric with respect to said plane for producing a non-reciprocal phase shift in light propagating through said fiber.
An optical fiber comprising a cladding and a core and a longitudinal direction for light propagation;
- said cladding having at least one flattened surface;
- and
- said core having no plane parallel to said flattened surface which is a plane of symmetry, wherein said core is asymmetric due to the presence of two different material forming two different parts of the core.
Dependencies are inferred from the claim text.