Fabrication of nanowires

Abstract

A method of forming a nanowire is disclosed. In one embodiment, a primary preform is formed comprising at least one central region and a support structure. The primary preform is then drawn to a cane, which is then inserted into an outer portion, to form a secondary preform. The secondary preform is then drawn until the at least one central portion is a nanowire. The method can produce nanowires of far greater length than existing methods, and can reduce the likelihood of damaging the nanowire when handling.

1 . A method of forming a fibre incorporating a nanowire, the method comprising:
 forming a primary preform comprising a central portion and a support structure for supporting the central portion;   drawing the primary preform to form a cane;   forming an outer portion having a cane receiving portion for receiving the cane;   inserting the cane into the cane receiving portion to form a secondary preform; and   drawing the secondary preform until the central portion is a nanowire.   
     
     
         2 . The method as claimed in  claim 1 , wherein the primary preform is formed by extrusion. 
     
     
         3 . The method as claimed in  claim 1 , wherein the outer portion is formed to provide a space leading to the cane receiving portion. 
     
     
         4 . The method as claimed in  claim 3 , wherein the space is a wedge-shaped cut-away in the outer portion. 
     
     
         5 . The method as claimed in  claim 3 , wherein the method further comprises etching away at least a part of the support structure that is exposed to the space to expose the nanowire. 
     
     
         6 . The method as claimed in  claim 1 , wherein the primary preform is made from a soft glass. 
     
     
         7 . The method as claimed in  claim 6 , where in the soft glass is lead silicate. 
     
     
         8 . The method as claimed in  claim 1 , wherein the primary preform is made from a polymer. 
     
     
         9 . A method of forming a nanowire, the method comprising:
 forming a preform structure comprising a central portion supported by a support structure, and an outer portion surrounding the central portion and the support structure; and   drawing the preform structure until the central portion is a nanowire.   
     
     
         10 . The method as claimed in  claim 9 , wherein the step of forming the preform structure comprises inserting the central portion and the support structure into the outer portion. 
     
     
         11 . A nanowire formed according to the method of  claim 9 . 
     
     
         12 . A method of forming a nanowire comprising drawing a cane having a central portion supported by a support structure until the central portion is a nanowire. 
     
     
         13 . A method of increasing the nonlinearity of a nanowire, the method comprising surrounding the nanowire with a nonlinear fluid. 
     
     
         14 . The method as claimed in  claim 13 , wherein the nanowire is surrounded by a support structure and an outer portion, defining at least one channel in fluid communication with the nanowire, the step of surrounding the nanowire with the nonlinear fluid comprising introducing the nonlinear fluid into the at least one channel. 
     
     
         15 . The method as claimed in  claim 14 , wherein the nonlinear fluid is carbon disulphide. 
     
     
         16 . A fibre incorporating a nanowire, formed by the method according to  claim 1 . 
     
     
         17 . A method of forming a fibre incorporating a plurality of nanowires, the method comprising:
 forming a primary preform comprising at plurality of central portions and a support structure for supporting the plurality of central portions;   drawing the primary preform to form a cane;   forming an outer portion having a cane receiving portion for receiving the cane;   inserting the cane into the cane receiving portion to form a secondary preform; and   drawing the secondary preform until the plurality of central portions are nanowires.   
     
     
         18 . A method as claimed in  claim 17 , wherein the outer portion is formed to provide a space leading to the cane receiving portion. 
     
     
         19 . A fibre containing a plurality of nanowires, the fibre made by the method of  claim 17 . 
     
     
         20 . A nanowire greater than 10 mm in length.