Low loss cladded optical fibers from halides and process for making same

Claim 2

The process of fabricating a low loss cladded halide fiber waveguide for transmission of infrared frequencies characterized by the steps of: forming a first ingot of a first halide compound having a first index of refraction; forming a second ingot of a second halide compound having an index of refraction less than the first index of refraction; forming a cylindrical billet core from the first ingot; forming a sleeve cladding for the cylindrical billet core from the second ingot; inserting the core coaxially in the sleeve cladding to form a composite billet; coaxially covering the composite billet with a non-hygroscopic polymer film; heating the composite billet to a temperature that renders the halide compounds and the polymer ductile; and extruding the heated composite billet through a die to form a cladded fiber having a protective outer polymer coating.

Claim 3

A process according to claim 1 characterized by the further step of rapidly cooling the extruded fiber.

Claim 4

A process according to claim 2 characterized by the further step of annealing the cooled fiber.

Claim 5

A process according to claim I characterized in that the step of covering the composite billet with said non-hygroscopic polymer film comprises inserting the composite billet coaxially in a cylindrical tube of the polymer and heat shrinking said tube around the composite billet.

Claim 6

A process according to claim 1 characterized in that the first and second halides are formed from a cation selected from the group consisting of sodium, potassium, cesium, silver and and thalium, and an anion selected from the group consisting of flourine, chlorine, bromine and iodine.

Claim 7

The process according to claim 1 characterized in that the first and second halides are selected from the group consisting of potassium chloride, potassium bromide, sodium chloride, thallium bromide, thallium chloride, thallium bromo-iodide, thallium bromo-iodo chloride, cesium iodide, cesium bromide, silver bromide and silver chloride.

Claim 8

The process according to claim 1 characterized in that before extrusion the core diameter is between about 3mm and about 6mm, the sleeve cladding radial thickness is between about lmm and about 3mm, and the polymer film radial thickness is between about 0.03mm and about 0.09mm.

Claim 9

The process according to claim 7 characterized in that the composite billet is extruded to an outside diameter of between about 0.075mm and about 2.0mm.

Claim 10

The process according to claim 1 characterized in that the first and second halides are selected from the group consisting of KCl, NaCl, NaBr and KBr, and extrusion is carried out at a temperature of between about room temperature and about 350°C.

Claim 11

The process according to claim 1 characterized in that the step of forming each ingot includes the steps of: baking a powder of the halide compound to remove impurities therefrom; melting the halide compound; and growing a single halide crystal from the halide compound to form an ingot.

Claim 12

The process according to claim 10 characterized in that the steps of baking and melting are performed in a vacuum environment.

Claim 13

The process according to claim 10 characterized in that the ingot-forming step includes the step of polishing the outer surface of ingots.

Claim 14

The process according to claim 1 characterized in that the non-hygroscopic polymer film is selected from the group consisting of mylar, polyethylene, polyvinyl fluoride, polyvinylidene chloride, nylon, tetrafluoroethylene polymer and cellophane.

Claim 15

The process according to claim 1 characterized by the further step of disposing the fiber coaxially in a strength member.

Claim 16

The process according to claim 14 characterized in that strength member is formed by extrusion around the fiber.

Claim 17

The process according to claim 14 characterized in that the strength member is formed by dipping the fiber in the material comprising the strength member.

Claim 18

The process according to claim l4 characterized by the steps of: disposing the fiber coaxially in a tube of the strength member having a coaxial space between the fiber and the inner surface of the tubing; filling the space with a liquid epoxy; and curing the epoxy to form a highly viscous semi-solid compound for cushioning and protecting the fiber.

Claim 19

The process according to claim 14 characterized by the further steps of: installing an infrared window at one end of the strength member; and installing a connector at the other end of the strength member.

Claim 20

The process according to claim 18 characterized in that the connector contains an infrared window.

Claim 21

The process of fabricating a low loss cladded halide fiber waveguide for transmission of infrared frequencies characterized by the steps of: forming a first ingot of a first halide compound having a first index of refraction; forming a second ingot of a second halide compound having an index of refraction less than the first index of refraction; forming a polymer-coated cylindrical billet core from the first ingot, said polymer coating comprising a first polymer film means for segregating said first and second halides during extrusion, said polymer means having a radial thickness so that segregation is achieved without appreciable absorption at infrared frequencies; forming a sleeve cladding for the cylindrical billet core from the second ingot; inserting the polymer-coated core coaxially in the sleeve cladding to form a composite billet; coaxially covering the composite billet with a second non-hygroscopic polymer film; heating the composite billet to a temperature that renders the halide compounds and the polymer films ductile; and extruding the heated composite billet through a die to form a cladded fiber having a protective outer polymer coating.

Claim 22

The process of fabricating a low loss cladded halide fiber waveguide for transmission of infrared frequencies characterized by the steps of: forming a first ingot of a first halide compound having a first index of refraction; forming a second ingot of a second halide compound having an index of refraction less than the first index of refraction; forming a polymer-coated cylindrical billet core from the first ingot, said polymer coating comprising a first polymer film means for segregating said first and second halides during extrusion, said polymer means having a radial thickness so that segregation is achieved without appreciable absorption at infrared frequencies; forming a sleeve cladding for the cylindrical billet core from the second ingot; inserting the polymer-coated core coaxially in the sleeve cladding to form a composite billet; coaxially covering the composite billet with a second non-hygroscopic polymer film; heating the composite billet to a temperature that renders the halide compounds and the polymer films ductile; and extruding the heated composite billet through a die to form a cladded fiber having a protective outer polymer coating.

Claim 23

The process according to claim 20 characterized in that the step of forming the polymer-coated cylindrical billet core comprises coextruding said first ingot and said first polymer film.

Claim 24

The process according to claim 20 characterized by the further step of rapidly cooling the extruded fiber.

Claim 25

The process according to claim 20 characterized in that the first and second halides are selected from the group consisting of potassium chloride, potassium bromide, sodium chloride, thallium bromide, thallium chloride, thallium bromo-iodide, thallium bromo-iodo chloride, cesium bromide, cesium iodide, silver bromide and silver chloride.

Claim 26

The process according to claim 20 characterized in that before extrusion the core diameter is between about 3mm and about 6mm, the sleeve cladding radial thickness is between about lmm and about 3mm, the first polymer film radial thickness is between about 0.03mm and about 0.06mm, and the second polymer film radial thickness is between about 0.03mm and about 0.09mm.

Claim 27

The process according to claim 20 characterized in that the composite billet is extruded to an outside diameter of between about 0.075mm and about 2.0mm.

Claim 28

The process according to claim 20 characterized in that the first and second halides are selected from the group consisting of KC1, NaCI, NaBr and KBr, and extrusion is carried out at a temperature of between about room temperature and about 350°C.

Claim 29

The process according to claim 20 characterized by the further step of disposing the fiber coaxially in a strength member.

Claim 30

The process according to claim 27 characterized in that the strength member is formed by extrusion around the fiber.

Claim 31

The process according to claim 27 characterized in that the strength member is formed by dipping the fiber in the material comprising the strength member.

Claim 32

The process according to claim 27 characterized by the steps of: disposing the fiber coaxially in a tube of the strength member having a coaxial space between the fiber and the inner surface of the tubing; filling the space with a liquid epoxy; and curing the epoxy to form a highly viscous semi-solid compound for cushioning and protecting the fiber.

Claim 33

The process according to claim 30 characterized by the further steps of: installing an infrared window at one end of the strength member; and installing a connector at the other end of the strength member.

Claim 34

A cladded optical fiber for transmission of electromagnetic energy in the infrared region of the spectrum characterized by: a cylindrical core formed from a first halide compound having a first index of refraction; a coaxial cladding layer disposed around said core formed from a second halide compound having a second index of refraction less than the first index of refraction; and non-hygroscopic polymer film means providing a continuous intimate covering around said fiber.

Claim 35

A cladded optical fiber for transmission of electromagnetic energy in the infrared region of the spectrum characterized by: a cylindrical core formed from a first halide compound having a first index of refraction; a coaxial cladding layer disposed around said core formed from a second halide compound having a second index of refraction less than the first index of refraction; and non-hygroscopic polymer film means providing a continuous intimate covering around said fiber.

Claim 36

A cladded optical fiber according to claim 32 characterized in that the diameter is between about 75 and about 2,000 microns.

Claim 37

A cladded optical fiber acording to claim 32 characterized in that the first and second halides are selected from the group consisting of potassium chloride, potassium bromide, sodium chloride, thallium bromide, thallium chloride, thallium bromo-iodide, thallium bromo-iodo chloride, cesium bromide, cesium iodide, silver bromide and silver chloride.

Claim 38

A cladded optical fiber according to claim 32 characterized in that the non-hygroscopic polymer film means is selected from the group consisting of mylar, polyethylene, polyvinyl fluoride, polyvinylidene chloride, nylon, teflon and cellophane.

Claim 39

A cladded optical fiber according to claim 32 characterized in that a non-hygroscopic polymer film is intermediate the cylindrical core and the coaxial cladding layer.

Claim 40

A cable for transmission of electromagnetic energy in the infrared portion of the spectrum characterized by: a cladded optical fiber having a cylindrical core formed from a first halide compound having a first index of refraction, a coaxial cladding layer disposed around said core and formed from a second halide compond having a second index of refraction less than the first index fraction, and a non-hygroscopic polymer film means providing a continuous intimate covering around said fiber; and a strength member coaxially disposed around said fiber.

Claim 41

A cable for transmission of electromagnetic energy in the infrared portion of the spectrum characterized by: a cladded optical fiber having a cylindrical core formed from a first halide compound having a first index of refraction, a coaxial cladding layer disposed around said core and formed from a second halide compond having a second index of refraction less than the first index fraction, and a non-hygroscopic polymer film means providing a continuous intimate covering around said fiber; and a strength member coaxially disposed around said fiber.

Claim 42

A cable according to claim 37 characterized in that the strength member is in intimate contact with the fiber.

Claim 43

A cable according to claim 38 characterized in that the strength member is formed by extrusion around the fiber.

Claim 44

A cable according to claim 38 characterized in that the strength member is formed by dipping the fiber in the material comprising the strength member.

Claim 45

A cable according to claim 37, characterized in that a jacket means is coaxially disposed around the strength member.

Claim 46

A cable according to claim 37 characterized in that a semi-solid viscous material is disposed to fill a coaxial space between the fiber and the inner surface of the strength member for cushioning and protecting said fiber.

Claim 47

A cable according to claim 37 characterized by: a window transparent to infrared energy disposed at the distal end of said cable; and a connector disposed at the proximal end of said cable for connecting to a source of infrared energy.

Claim 48

A cable according to claim 37 characterized by a nonhygroscopic film intermediate the cylindrical core and the coaxial cladding layer.

Claim 49

A cable according to claim 43 characterized in that the connector contains a window transparent to infrared energy.

Claim 50

A cable according to claim 42 characterized in that a first portion of said coaxial space is filled with said viscous material and a second portion of said space is filled with a rigid material.

Claim 51

A cable according to claim 42 characterized in that said semi-solid viscous material is an epoxy compound.