Low phonon energy gain medium and related active devices

Abstract

Using sol-gel techniques, an optical gain medium has been fabricated comprising a glass ceramic host material that includes clusters of crystalline oxide material, especially tin oxide, and that is doped with active ions concentrated at the clusters. The active ions are preferentially located at the nanoclusters so that they experience the relatively low phonon energy of the oxide and are insensitive to the phonon energy of the host. A host with a high phonon energy, such as silica, can therefore be used without the usual drawback of reduced carrier lifetimes through enhanced nonradiative decay rates.

1 . An optical gain medium comprising a glass ceramic host material that includes clusters of crystalline oxide material and that is doped with active ions concentrated at the clusters.  
     
     
         2 . An optical gain medium according to  claim 1 , wherein the clusters contain tin oxide.  
     
     
         3 . An optical gain medium according to  claim 2 , wherein the tin oxide is substantially pure.  
     
     
         4 . An optical gain medium according to  claim 2 , wherein the tin oxide is present in a concentration of greater than 0.5 mol %.  
     
     
         5 . An optical gain medium according to  claim 2 , wherein the tin oxide is present in concentration of greater than 0.5 mol % and up to 30 mol %.  
     
     
         6 . An optical gain medium according to  claim 1 , wherein the crystalline oxide material includes an oxide of at least one of zirconium, scandium, yttrium, lutetium, titanium and hafnium.  
     
     
         7 . An optical gain medium according to  claim 1 , wherein the active ions are rare earth ions.  
     
     
         8 . An optical gain medium according to  claim 7 , wherein the rare earth ions are erbium ions.  
     
     
         9 . An optical gain medium according to  claim 7 , wherein the rare earth ions are thulium ions.  
     
     
         10 . An optical gain medium according to  claim 1 , wherein the host material is silica or a silicate glass.  
     
     
         11 . A laser comprising an optical gain medium comprising a glass ceramic host material that includes clusters of crystalline oxide material and that is doped with active ions concentrated at the clusters.  
     
     
         12 . An optical amplifier comprising an optical gain medium comprising a glass ceramic host material that includes clusters of crystalline oxide material and that is doped with active ions concentrated at the cluster.  
     
     
         13 - 17 . (canceled)