Direct extrusion method for the fabrication of photonic band gap (PBG) fibers and fiber preforms

A method for manufacturing a microstructured optical fiber, comprising:

• providing a preform die in operative communication with a barrel of an extruder, the preform die comprising at least an inlet in a first end of the preform die for receiving softened glass from the barrel of the extruder, an outer portion having channels therein for directing the softened glass received from the barrel through the preform die, a center pin, a plurality of surrounding pins around the center pin and arranged in a desired periodic pattern, and an outlet in a second end of the preform die;
• providing a specialty glass transmissive to light in the infra-red wavelengths above 2 μm and charging the same to the barrel of the extruder;
• heating at least one of the barrel and the specialty glass to soften the glass and forcing the softened glass from the barrel through the inlet and into the outer portion of the preform die;
• allowing the softened glass to flow through the channels of the preform die and around the center pin and the plurality of surrounding pins;
• extruding a preform comprising at least an inner core corresponding to the center pin of the preform die, and a cladding around the core, the cladding including a plurality of air holes corresponding to the plurality of surrounding pins of the preform die and arranged in the periodic pattern of the pins in the preform die, each air hole comprising a longitudinal opening extending through the entire length of the preform, the preform being substantially free of interfacial and interstitial voids;
• and
• placing the extruded preform into a draw tower and drawing the preform into the microstructured optical fiber, wherein the fiber has a smaller dimension than the extruded preform and retains the periodic pattern of the preform.