At&t Bell Laboratories

Bell Telephone Laboratories

William Pleibel

Rogers H Stolen

Richard E Howard

Jay R Simpson

Roger H Stolen

Selected portions of the interior surface of a substrate tube, or of the cladding or core layers deposited on the interior surface of the substrate tube, are treated by one or more process steps such as shaping, diffusing, leaching, or depositing. Patterning processes such as photolithography and lift-off are employed to define the selected portions. The resulting core and/or cladding layers of the fiber can be made to have a variety of geometric shapes and composition profiles useful, for example, in realizing birefringent fibers and multiple-core fibers. Also described is the similar treating of metal layers and the incorporation of such layers into the fiber.

Optical fiber with embedded metal layer

The present invention relates to a technique for producing polarization-preserving and single polarization optical fibers. As disclosed, high birefringence is introduced into the preform by deforming the fiber preform such that a cladding layer becomes flat and highly conformable, while the core remains hard and substantially round. In particular, a cladding layer with a relatively low melting point is utilized such that when the preform is heated the cladding becomes liquified while the core remains solid. The preform may then be deformed so that the cladding layer is substantially flattened. Standard drawing techniques may then be utilized to form polarization-preserving fibers and single polarization fibers from the preform.

Method of fabricating high birefringence fibers

The present invention relates to a single-mode single-polarization optical fiber which is capable of functioning as an in-line fiber polarizer which allows only one polarization of the fundamental mode to propagate along the fiber. In structure, the fiber comprises a central core region (10) and a cladding region (12) which is substantially in contact with the central core region. The various regions are formed such that the refractive index of an outer cladding region is greater than the refractive index of an inner cladding region but less than that of the core region. The arrangement of the present invention produces stress-birefringence between the cladding regions and the central core region sufficient to split the two orthogonal polarizations (n.sub..parallel. and n.sub..perp.) of the fundamental mode such that the desired polarization propagates freely and the undesired polarization is attenuated by tunneling through the cladding layers.

Single-mode single-polarization optical fiber

Lithographic method of making optical fibers

A method of making a polarization-preserving optical fiber is disclosed having a first step of fabricating a substrate tube to have a wall of nonuniform thickness, the nonuniformity in thickness being arranged about the wall of the substrate tube so that maxima and minima in wall thickness lie in planes which are substantially orthogonal. This first step is followed by deposition of cladding layers and a core layer within the substrate tube. The substrate is then collapsed and the fiber drawn therefrom. The nonuniform wall thickness of the substrate tube operates together with differential thermal contraction of the layers to produce stress-induced birefringence in the fiber, which birefringence provides a polarization-preserving optical fiber.

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Matawan, NJ, United States of America

William Pleibel