Accelerated method for increasing the photosensitivity of a glassy material

Abstract

A method for rapidly increasing the photosensitivity of an optical fiber comprising the step of providing an optical fiber comprising a glassy material and a thermally-stable coating. The thermally-stable coating has a thermally-stable exposure band, wherein desired time/temperature exposure parameters fall within the time/temperature thermal stability exposure band for the coating. The optical fiber is exposed for the desired time/temperature exposure to a hydrogen-containing atmosphere. The desired temperature is more than 250° C. and the desired time exposure does not exceed one hour. The glassy material then may be irradiated with actinic radiation, such that the refractive index of the irradiated portion results in a normalized index change of at least 10 −5 .

What is claimed is:  
     
         1 . A method for producing an optical fiber having an optical grating, comprising the steps of: 
 providing an optical fiber having a glass core and a thermally stable exterior coating; exposing first and second portions of said optical fiber to a hydrogen-containing atmosphere under exposure conditions comprising (a) an exposure temperature of greater than 250° C., and (b) an exposure time of less than about 1 hour, thereby forming a treated optical fiber wherein the coating is thermally stable during and after the exposing step; and    writing an optical grating on the treated optical fiber without removing the coating such that said first portion of the optical fiber contains the grating and said second portion of the optical fiber is devoid of any grating,    wherein the exposure time is within the range of about 1 minute to about 10 minutes.    
     
     
         2 . The method of  claim 1 , wherein the exposure time is within the range of about 1 minute to about 5 minutes.  
     
     
         3 . The method of  claim 1 , wherein the optical fiber is rapidly cooled after exposure to the hydrogen-containing atmosphere, wherein the cooling includes placing the fiber on a cold thermally conductive surface.  
     
     
         4 . A method for improving the photosensitivity of an optical fiber, comprising the steps of: 
 providing an optical fiber comprising a glass core and an exterior coating; and    exposing the optical fiber to a hydrogen-containing atmosphere under exposure conditions comprising (a) a temperature of greater than 250° C., and (b) an exposure time of less than about 1 hour;    wherein the coating is thermally stable under the exposure conditions.    wherein the exposure time is within the range of about 1 minute to about 10 minutes.    
     
     
         5 . The method of  claim 4 , wherein the exposure time is within the range of about 1 minute to 5 minutes.  
     
     
         6 . The method of  claim 4 , wherein the optical fiber is rapidly cooled after exposure to the hydrogen-containing atmosphere by placing the fiber on a cold thermally conductive surface.  
     
     
         7 . A method for producing an optical fiber having increased photosensitivity, comprising the steps of: 
 providing an optical fiber comprising a glass core and a thermally stable exterior coating;    exposing the optical fiber to hydrogen gas heated to a temperature of greater than 250° C. until the optical fiber is essentially saturated with hydrogen, thereby forming a treated optical fiber and wherein the coating is thermally stable under the conditions at which it is exposed to the hydrogen gas; and rapidly cooling the treated optical fiber,    wherein the optical fiber is exposed to the hydrogen gas for an exposure time within the range of about 1 minute to about 10 minutes.    
     
     
         8 . The method of  claim 7 , wherein the optical fiber is exposed to the hydrogen gas for an exposure time within the range of about 1 minutes to about 5 mines.  
     
     
         9 . The method of  claim 7 , wherein the optical fiber is rapidly cooled after exposure to the hydrogen-containing atmosphere by placing the fiber on a cold thermally conductive surface.