Hollow core optical fiber with controlled diameter hollow regions and apparatus for making the same

Abstract

An apparatus for fabricating a hollow core optical fiber with a controllable core region (in terms of diameter) is based upon regulating conditions (gas flow, volume, and/or temperature) within the hollow core region during the fiber draw process. The introduction of a gas, or any change in volume or temperature of the hollow core region, allows for the diameter of the hollow core region to self-regulate as a multistructured core rod (MCR) is drawn down into the final hollow core optical fiber structure. This self-regulation provides a core region having a diameter that selected and then stabilized for the duration of the draw process. The inventive apparatus is also useful in controlling the diameter of any selected hollow region of an MCR including, but not limited to, shunts and corner capillaries disposed around the core region.

What is claimed is: 
     
         1 . Apparatus for controlling a diameter of one or more hollow regions during draw of a hollow core microstructure, the apparatus including
 external means coupled to at least one hollow region of a starting material for regulating conditions within the at least one hollow region during draw to maintain a desired diameter of the at least one hollow region, the one or more conditions selected from the group consisting of gas flow rate through the at least one of the hollow regions, the volume of the at least one of the hollow regions, and the temperature within the at least one of the hollow regions.   
     
     
         2 . The apparatus as defined in  claim 1  wherein the external means comprises an external pump source for providing a flow of gas through the at least one hollow region during draw. 
     
     
         3 . The apparatus as defined in  claim 2  wherein the external pump source is configured to provide a constant flow rate of gas through the at least one hollow region. 
     
     
         4 . The apparatus as defined in  claim 2  wherein the external pump source is configured to provide a variable flow rate of gas through the at least one hollow region. 
     
     
         5 . The apparatus as defined in  claim 1  wherein the external means comprises a movable plunger disposed within the at least one hollow region, the movement of the plunger during draw providing a continuous change in a volume of the at least one hollow region during draw. 
     
     
         6 . The apparatus as defined in  claim 1  wherein the external means comprises an external heat source for heating a gas supplied to the at least one hollow region. 
     
     
         7 . The apparatus as defined in  claim 1  wherein the external means is coupled to a hollow core region of the structure. 
     
     
         8 . The apparatus as defined in  claim 1  wherein the external means includes at least one source coupled to a shunt region. 
     
     
         9 . The apparatus as defined in  claim 1  wherein the external means includes at least one source coupled to a corner capillary.