Microstructured optical fibers and preforms and methods for fabricating microstructured optical fibers

A microstructured optical fiber preform for the fabrication of a microstructured optical fiber, the microstructured optical fiber being for the propagation of an optical signal at a desired wavelength, the microstructured optical fiber preform comprising:

• an inner region including an inner material and a plurality of holes formed in the inner material, the inner material having a refractive index at the desired wavelength and a softening point temperature;
• and
• an outer region disposed about the inner region, the outer region including an outer material surrounding the inner region, the outer material having a refractive index at the desired wavelength and a softening point temperature,
• wherein the softening point temperature of the inner material is greater than the softening point temperature of the outer material by at least about 50° C.

A method of making a microstructured optical fiber, comprising the steps of:

• providing a preform, the preform having
• an inner region including a core, an inner material and a plurality of holes formed in the inner material, the inner material having a refractive index at the desired wavelength and a softening point temperature, and
• an outer region disposed about the inner region, the outer region including an outer material surrounding the inner region, the outer material having a refractive index at the desired wavelength and a softening point temperature,
• wherein the softening point temperature of the inner material is greater than the softening point temperature of the outer material by at least about 50° C.;
• and
• drawing the preform to form the microstructured optical fiber.