Composite polymer fibers
A composite polymer fiber comprises a polymer filler material and a plurality of polymer scattering fibers disposed within the filler material. At least one of the filler material and the scattering fibers is formed of a birefringent material. The refractive indices of the filler material and the scattering fibers can be substantially matched for light incident in a first polarization state on the composite polymer fiber and unmatched for light incident in an orthogonal polarization state. The scattering fibers may be arranged to form a photonic crystal within the composite fiber. The composite fibers may be extruded and may be formed into a yarn, a weave or the like. If the filler material is soluble, it may be washed out of the yarn or weave, and the scattering fibers may then be infiltrated with a resin that is subsequently cured.
1. A composite polymer fiber, comprising:
a polymer filler material; and
a plurality of polymer scattering fibers disposed within the filler material, the scattering fibers having longitudinal axes substantially parallel to a longitudinal axis of the composite polymer fiber;
wherein at least one of the filler material and the scattering fibers is formed of a birefringent material, the refractive indices of the filler material and the scattering fibers being substantially matched for light incident in a first polarization state on the composite polymer fiber and being substantially unmatched for light incident in a second polarization state orthogonal to the first polarization state.
2. A composite fiber as recited in claim 1 , wherein the fiber has a substantially circular cross-section.
3. A composite fiber as recited in claim 1 , wherein the fiber has a substantially non-circular cross-section.
4. A composite fiber as recited in claim 1 , wherein at least some of the scattering fibers have a substantially circular cross-section.
5. A composite fiber as recited in claim 1 , wherein at least some of the scattering fibers have a substantially non-circular cross-section.
6. A composite fiber as recited in claim 1 , wherein at least some of the scattering fibers are twisted together.
7. A composite fiber as recited in claim 1 , wherein at least some of the scattering fibers are arranged irregularly across a cross-section of the composite fiber.
8. A composite fiber as recited in claim 1 , wherein at least some of the scattering fibers are arranged regularly across a cross-section of the composite fiber.
9. A composite fiber as recited in claim 8 , wherein at least some of the scattering fibers are arranged at locations of a regular grid pattern across the cross-section of the composite fiber, with at least one location of the regular grid pattern having no scattering fiber.
10. A composite fiber as recited in claim 8 , wherein at least some of the scattering fibers are arranged within the composite fiber so that the arrangement of scattering fibers provides spectrally selective properties for light laterally incident on the composite fiber.
11. A composite fiber as recited in claim 1 , further comprising cover layers surrounding respective scattering fibers.
12. A composite fiber as recited in claim 11 , wherein the scattering fibers are formed of a scattering fiber material and the cover layer is formed of one of the filler material and the scattering fiber material.
13. A composite fiber as recited in claim 1 , wherein at least one of the scattering fibers comprises a shell surrounding a core, the shell and core being formed of different materials.
14. A composite fiber as recited in claim 1 , wherein at least one of the scattering fibers comprises a disperse phase of a first polymer material in a continuous phase of a second polymer material.