Long period fiber Bragg gratings written with alternate side IR laser illumination

Abstract

A method of optical fiber manufacture involves the writing of a grating on the fiber using a laser. A first laser beam is directed on a first locality of the fiber having a circumference. A second laser beam is then directed on a second locality circumferentially displaced from the first locality. The first laser beam may be the second laser beam. In this way, a grating is formed on the fiber. The fiber may have a core and a cladding layer. The fiber may also comprise two gratings to form an interferometer.

What is claimed is:  
     
         1 . A method of optical fiber manufacture comprising the steps of: 
 directing a first laser beam on a first locality of an optical fiber having a circumference;    directing a second laser beam on a second locality of the optical fiber circumferentially displaced from the first locality; and    forming a grating on the optical fiber.    
     
     
         2 . The method of optical fiber manufacture of  claim 1  wherein the first laser beam comprises the second laser beam.  
     
     
         3 . The method of optical fiber manufacture of  claim 1  wherein at least one of the laser beams heats the optical fiber to form the grating.  
     
     
         4 . The method of optical fiber manufacture of  claim 3  wherein the optical fiber is deformed about one of the localities.  
     
     
         5 . The method of optical fiber manufacture of  claim 1  wherein at least one of the laser beams arises from a carbon dioxide laser source.  
     
     
         6 . The method of optical fiber manufacture of  claim 1  wherein at least one of the laser beams arises from an infrared laser source.  
     
     
         7 . The method of optical fiber manufacture of  claim 1  wherein at least one of the laser beams traces at least in part a scanning pattern.  
     
     
         8 . The method of optical fiber manufacture of  claim 7  wherein at least one of the laser beams arises from a laser source activated at predetermined points of the scanning pattern.  
     
     
         9 . The method of optical fiber manufacture of  claim 1  wherein the optical fiber comprises a transmission layer and a cladding layer.  
     
     
         10 . The method of optical fiber manufacture of  claim 9  wherein at least two gratings are formed.  
     
     
         11 . A system for optical fiber manufacture comprising: 
 a laser source;    a first turning mirror having a first reflective face for receiving a first laser beam from said laser source and for reflecting said first laser beam on an optical fiber having a circumference; and    a second turning mirror having a second reflective face for receiving a second laser beam from said laser source and for reflecting said second laser beam on said optical fiber.    
     
     
         12 . The system for optical fiber manufacture of  claim 11  wherein said first laser beam comprises said second laser beam.  
     
     
         13 . The system of  claim 11  wherein said first reflective face at least partially faces said second reflective face.  
     
     
         14 . The system of  claim 11  wherein each of said turning mirrors generally directs a laser along the same axis.  
     
     
         15 . The system of  claim 14  wherein at least one of said turning mirrors is angled about 45 degrees relative to said axis.  
     
     
         16 . The system of  claim 11  wherein said first turning mirror directs said first laser beam on a first locality of said optical fiber and said second turning mirror directs a second laser beam on a second locality circumferentially displaced from said first locality.  
     
     
         17 . The system of  claim 11  including at least one scanning mirror directing at least one of said laser beams on at least one of said turning mirrors.  
     
     
         18 . The system of  claim 17  wherein said at least one scanning mirror comprises a first scanning mirror having a first reflective face and a second scanning mirror having a second reflective face.  
     
     
         19 . The system of  claim 17  wherein a computer controls said at least one scanning mirror.  
     
     
         20 . An optical fiber made by a process comprising the steps of: 
 directing a first laser beam on a first locality of an optical fiber having a circumference;    directing a second laser beam on a second locality of the optical fiber circumferentially displaced from the first locality; and    forming a grating on the optical fiber.