Y-branch-based thermo-optic digital optical switches and variable optical attenuators with non-uniform heating

Abstract

The present invention is concerned with 1×2 thermo-optic digital optical switches known in the art as “Y-branch digital optical switches” and variable optical attenuators.

1 . A 1×2 planar optical waveguide signal splitter in the form of a Y-branch comprising a trunk and two branches conjoined thereto to form a vertex, said branches diverging from one another, each of said branches having a surface, at least one of said branches being provided with a heating means, said heating means being disposed with respect to said at least one of said branches such that upon activation of said heating means, a spatially non-uniform heat flux will be incident upon said at least one of said branches.  
   
   
       2 . The 1×2 planar optical waveguide signal splitter of  claim 1  wherein each of said branches further comprises an outer edge and wherein further said spatially non-uniform heat flux will be incident preponderantly on said outer edge of said at least one of said branches.  
   
   
       3 . The 1×2 planar optical waveguide signal splitter of  claim 1  wherein said vertex is characterized by an angle of 0.05-4°.  
   
   
       4 . The 1×2 planar optical waveguide signal splitter of  claim 3  wherein said vertex is characterized by an angle of 0.4-1°.  
   
   
       5 . The 1×2 planar optical waveguide signal splitter of  claim 1  wherein said heating means is of uniform cross-section.  
   
   
       6 . The 1×2 planar optical waveguide signal splitter of  claim 1  wherein said heating means is of non-uniform cross-section.  
   
   
       7 . The 1×2 planar optical waveguide signal splitter of  claim 1  further comprising a polymeric core.  
   
   
       8 . The 1×2 planar optical waveguide signal splitter of  claim 7  wherein said polymeric core comprises a polymer selected from the group consisting of polyacrylates, polyfluoroacrylates, polychloroacrylates, polymethacrylates, and polycarbonates.  
   
   
       9 . The 1×2 planar optical waveguide signal splitter of  claim 8  wherein the polymer is a polyfluoroacrylate.  
   
   
       10 . The 1×2 planar optical waveguide signal splitter of  claim 1  wherein said heating means is an electrical resistance heater.  
   
   
       11 . The 1×2 planar optical waveguide signal splitter of  claim 10  wherein said electrical resistance heater is of non-uniform cross-section.  
   
   
       12 . The 1×2 planar optical waveguide signal splitter of  claim 11  wherein said cross-section has a minimum area, said heater being disposed such that the distance between said vertex and said minimum area is a minimum.  
   
   
       13 . A method for splitting an optical signal, the method comprising: 
 (a) disposing in the propagation path of a propagating optical signal a 1×2 planar optical waveguide signal splitter in the form of a Y-branch comprising a trunk and two branches conjoined thereto to form a vertex said branches diverging from one another, at least one of said branches being provided with a heating means, said heating means being disposed with respect to said at least one of said branches such that upon activation of said heating means, a spatially non-uniform heat flux will be incident upon said at least one of said branches; and    (b) energizing said heating means to effect the imposition of a spatially non uniform heat-flux upon the surface of said at least one of said branches in order to effect a rise in the temperature of said at least one of said branches an amount sufficient to cause a change in the relative intensity of the propagating optical signal in the two said branches.    
   
   
       14 . The method of  claim 13  wherein each of said branches further comprises an outer edge and wherein further said spatially non-uniform heat flux is imposed preponderantly on said outer edge of said at least one of said branches.  
   
   
       15 . The method of  claim 13  wherein said heating means is of non-uniform cross-section.  
   
   
       16 . The method of  claim 13  wherein said vertex is characterized by an angle of 0.05-4°.  
   
   
       17 . The method of  claim 16  wherein said vertex is characterized by an angle of 0.4-1°.  
   
   
       18 . The method of  claim 13  wherein said rise in temperature is sufficient to effect a digital optical switching function.  
   
   
       19 . The method of  claim 13  wherein said rise in temperature is insufficient to effect a digital optical switching function, so that said 1×2 planar optical waveguide signal splitter serves as a variable optical attenuator.  
   
   
       20 . The method of  claim 13  wherein said 1×2 planar optical waveguide signal splitter further comprises a polymeric core.  
   
   
       21 . The method of  claim 16  wherein said polymeric core comprises a polymer selected from the group consisting of polyacrylates, polyfluoroacrylates, polymethacrylates, and polycarbonates.  
   
   
       22 . The method of  claim 21  wherein the polymer is a polyfluoroacrylate.  
   
   
       23 . The method of  claim 13  wherein said heating means is an electrical resistance heater.  
   
   
       24 . The method of  claim 23  wherein said electrical resistance heater is of non-uniform cross-section.  
   
   
       25 . The method of  claim 23  wherein the highest heat flux is imposed at a minimum distance from said vertex.  
   
   
       26 . A digital optical spatial switch comprising the 1×2 planar optical waveguide signal splitter of  claim 1 .  
   
   
       27 . A variable optical attenuator comprising the 1×2 planar optical waveguide signal splitter of  claim 1.