Rare earth doped and large effective area optical fibers for fiber lasers and amplifiers

Abstract

Various embodiments described herein include rare earth doped glass compositions that may be used in optical fiber and rods having large core sizes. Such optical fibers and rods may be employed in fiber lasers and amplifiers. The index of refraction of the glass may be substantially uniform and may be close to that of silica in some embodiments. Possible advantages to such features include reduction of formation of additional waveguides within the core, which becomes increasingly a problem with larger core sizes.

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         8 . A method of fabricating rare earth ion doped glass, said method comprising:
 stacking multiple rods comprising rare earth ion doped glass; and   drawing said stacked rods to form a first rod.   
     
     
         9 . The method of  claim 8 , further comprising:
 iii) cutting said first rod into shorter sections;   iv) stacking said shorter sections; and   v) drawing said stacked sections to form a second rod.   
     
     
         10 . The method of  claim 9 , wherein said second rod has an effective refractive index uniformity with less than about 5×10 −4  maximum peak-to-peak variation measured with refractive index profiler with a spatial resolution of between 0.1 to 0.5 μm. 
     
     
         11 . The method of  claim 9 , wherein said second rod has an effective refractive index uniformity with less than about 1×10 −4  maximum peak-to-peak variation measured with refractive index profiler with a spatial resolution of between 0.1 to 0.5 μm. 
     
     
         12 . The method of  claim 9 , wherein said second rod has an average refractive index that is within about 1×10 −3  of the refractive index of fused silica. 
     
     
         13 . The method of  claim 9 , further comprising:
 vi) cutting said second rod into shorter sections;   vii) stacking said shorter sections of said second rod; and   viii) drawing said stacked sections of said second rod to form a third rod.   
     
     
         14 . The method of  claim 8 , further comprising including at least one un-doped rod with said multiple rods comprising rare earth ion doped glass stacked in step i). 
     
     
         15 . The method of  claim 14 , wherein the ratio of rods comprising rare earth ion doped glass to un-doped rods is at least about 2:1. 
     
     
         16 . The method of  claim 14 , wherein the ratio of rods comprising rare earth ion doped glass to un-doped rods is at least about 5:1. 
     
     
         17 . The method of  claim 14 , wherein the ratio of rods comprising rare earth ion doped glass to un-doped rods is at least about 10:1. 
     
     
         18 . The method of  claim 14 , wherein the ratio of rods comprising rare earth ion doped glass to un-doped rods is at least about 20:1. 
     
     
         19 . The method of  claim 8 , wherein no un-doped rods are stacked together with said rods comprising rare earth ion doped glass. 
     
     
         20 . An optical fiber where at least part of the core is fabricated using the process of  claim 8 . 
     
     
         21 . A step index fiber where at least part of the core is fabricated using the process of  claim 8 . 
     
     
         22 . The method of  claim 8 , further comprising:
 iii) repeating steps i) and ii) multiple times to produce at least a plurality of rods;   iv) stacking the plurality of rods together with the first rod to form a second rod.   
     
     
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