Fabrication of high air fraction photonic band gap fibers

Abstract

A photonic band gap fiber and method of making thereof is provided. The fiber is made of a non-silica-based glass and has a longitudinal central opening, a microstructured region having a plurality of longitudinal surrounding openings, and a jacket. The air fill fraction of the microstructured region is at least about 40%. The fiber may be made by drawing a preform into a fiber, while applying gas pressure to the microstructured region. The air fill fraction of the microstructured region is changed during the drawing.

1 . A method of making a fiber comprising the steps of: 
 providing a preform comprising a non-silica-based glass,    wherein the preform is cylindrical, having a longitudinal central opening and a microstructured region comprising a plurality of longitudinal surrounding openings disposed around the central opening; and    wherein the diameter of the central opening is larger than the diameter of any surrounding opening that is adjacent to the central opening;    pressurizing surrounding openings with a gas; and    drawing the preform into a fiber at an elevated temperature while maintaining the gas pressure to retain the longitudinal central opening and the microstructured region;    wherein the air fill fraction of the microstructured region of the fiber is different from the air fill fraction of the microstructured region of the preform.    
   
   
       2 . The method of  claim 1 , wherein diameters of the surrounding openings of the preform are approximately the same.  
   
   
       3 . The method of  claim 2 , wherein the diameter of the central opening of the preform is at least two times the diameter of the surrounding openings of the preform.  
   
   
       4 . The method of  claim 1 , wherein the air fill fraction of the microstructured region of the fiber is larger than the air fill fraction of the microstructured region of the preform.  
   
   
       5 . The method of  claim 1 , wherein the central opening is pressurized with the gas.  
   
   
       6 . The method of  claim 5 , wherein the gas pressure in the central opening is controlled independently from the gas pressure in the surrounding openings.  
   
   
       7 . The method of  claim 6 , wherein the gas pressure in the central opening is less than the gas pressure in the surrounding openings.  
   
   
       8 . The method of  claim 1 , wherein the gas pressure is controlled at a substantially constant pressure during the drawing step.  
   
   
       9 . The method of  claim 1 , wherein the gas is selected from the group consisting of inert gases, nitrogen, argon, and helium.  
   
   
       10 . The method of  claim 1 , wherein the gas pressure is maintained at a pressure that results in a fiber having an air fill fraction of the microstructured region of at least about 40%.  
   
   
       11 . The method of  claim 1 , wherein the gas pressure is maintained at a pressure that results in a fiber having an air fill fraction of the microstructured region of at least about 70%.  
   
   
       12 . The method of  claim 1 , wherein the gas pressure is maintained at a pressure that results in a fiber having an air fill fraction of the microstructured region of at least about 90%.  
   
   
       13 . The method of  claim 1 , wherein the preform comprises a jacket material comprising the non-silica-based glass surrounding the microstructured region.  
   
   
       14 . The method of  claim 1 , wherein the diameter of the fiber is from about 80 microns to about 1000 microns.  
   
   
       15 . The method of  claim 1 , wherein the non-silica-based glass is a chalcogenide glass.  
   
   
       16 . The method of  claim 1 , wherein the non-silica-based glass is selected from the group consisting of chalcogenide glass, germanate glass, phosphate glass, tellurite glass, borate glass, antimonate glass, and halide glass.  
   
   
       17 . A fiber comprising non-silica-based glass, comprising: 
 a longitudinal central opening;    a microstructured region comprising a plurality of longitudinal surrounding openings disposed around the central opening; and    a jacket surrounding the microstructured region;    wherein the air fill fraction of the microstructured region is at least about 40%.    
   
   
       18 . The fiber of  claim 17 , wherein the air fill fraction of the microstructured region is at least about 70%.  
   
   
       19 . The fiber of  claim 17 , wherein the air fill fraction of the microstructured region is at least about 90%.  
   
   
       20 . The fiber of  claim 17 , wherein the non-silica-based glass is a chalcogenide glass.  
   
   
       21 . The fiber of  claim 17 , wherein the non-silica-based glass is selected from the group consisting of chalcogenide glass, germanate glass, phosphate glass, tellurite glass, borate glass, antimonate glass, and halide glass.  
   
   
       22 . The fiber of  claim 17 , wherein the fiber has a diameter of about 80 microns to about 1000 microns.  
   
   
       23 . The fiber of  claim 17 , wherein the fiber is a photonic band gap fiber having a photonic band gap centered beyond a wavelength of about 2 microns.  
   
   
       24 . The fiber of  claim 23 , wherein the band gap lies within the wavelength region of from about 2 microns to about 15 microns.