High-response electro-optic modulator based on an intrinsically acentric, layer-by-layer self-assembled molecular superlattice

Abstract

A new electro-optic (EO) phase modulator constructed from a combination of a low-loss passive polymer waveguide and a self-assembled chromophore superlattice (SAS) with an intrinsically polar microstructure. In contrast to typical polymer-based modulators, the present invention utilizes a siloxane SA methodology that enables the acentric alignment of constituent chromophores during film growth without the need for post-deposition electric field poling. The guiding layer is constructed of the SAS and the glassy polymer Cyclotene™. The use of SiO 2 , Cytop™ and Cyclotene™ glassy polymers, results in a straightforward device fabrication process that is compatible with the thermally and photochemically robust SAS. Thus, nanoscale control of the film architecture results in greatly simplified macroscopic device fabrication. The present invention provides a SAS-based electro-optic modulator demonstrating excellent electro-optic response properties and a π phase shift.

What is claimed is:  
     
         1 . An electro-optic modulator comprising a waveguide having a glassy polymer layer having a first refractive index and being disposed on a self-assembled superlattice (SAS) with an intrinsic polar microstructure and having a second refractive index that is approximately equal to said first refractive index at a predetermined wavelength.  
     
     
         2 . An electro-optic modulator as recited by  claim 1 , wherein said glassy polymer layer is Cyclotene™ and wherein said second refractive index is approximately equal to 1.56.  
     
     
         3 . An electro-optic modulator as recited by  claim 1 , wherein said glassy polymer layer has a first width and wherein said SAS has a second width that is greater than or equal to said first width.  
     
     
         4 . An electro-optic modulator as recited by  claim 4 , wherein said first width is approximately equal to 4.0 μm.  
     
     
         5 . An electro-optic modulator as recited by  claim 1 , wherein said SAS comprises a plurality of molecular chromophore fragments each consisting of a plurality of electron donating and accepting groups interconnected by a conjugated π-electron system and exhibiting a large molecular hyperpolarizability, said donating and accepting groups of one molecular chromophore fragment being connected to said donating and accepting groups of another molecular chromophore fragment by silicon-oxygen linkages to form an acentric layered structure exhibiting a large electro-optic coefficient.  
     
     
         6 . An electro-optic modulator as recited by  claim 1 , wherein said glassy polymer is Cyclotene™ and wherein said predetermined wavelength is approximately equal to one of 1064 nm, 1300 nm and 1550 nm.  
     
     
         7 . An electro-optic phase modulator comprising: 
 a substrate;    a first electrode disposed on top of said substrate;    a bottom cladding layer disposed on top of said first electrode having a first refractive index;    a waveguide disposed on said bottom cladding layer and comprising: 
 a self-assembled superlattice (SAS) chemically bonded to said bottom cladding layer and having a second refractive index; and  
 a first glassy polymer having a third refractive index approximately equal to said second refractive index at a predetermined wavelength;  
   a second glassy polymer top cladding layer disposed on top of said SAS film and having a fourth refractive index; and    a second electrode disposed on top of said top cladding layer.    
     
     
         8 . An electro-optic phase modulator as recited by  claim 7 , wherein said SAS comprises a plurality of molecular chromophore fragments each consisting of a plurality of electron donating and accepting groups interconnected by a conjugated π-electron system and exhibiting a large molecular hyperpolarizability, said donating and accepting groups of one molecular chromophore fragment being connected to said donating and accepting groups of another molecular chromophore fragment by silicon-oxygen linkages to form an acentric layered structure exhibiting a large electro-optic coefficient.  
     
     
         9 . An electro-optic phase modulator as recited by  claim 7 , wherein said first glassy polymer is Cyclotene™ and wherein said second refractive index is approximately equal to 1.56.  
     
     
         10 . An electro-optic phase modulator as recited by  claim 9 , wherein said predetermined wavelength is approximately equal to one of 1064 nm, 1300 nm, and 1550 nm.  
     
     
         11 . An electro-optic phase modulator as recited by  claim 9 , wherein said second glassy polymer is Cytop™ and wherein said fourth refractive index is approximately equal to 1.34.  
     
     
         12 . An electro-optic phase modulator as recited by  claim 7 , wherein said first cladding layer is SiO 2 .  
     
     
         13 . An electro-optic phase modulator as recited by  claim 7 , wherein said first and said second electrodes are gold.  
     
     
         14 . A method of forming an electro-optic phase modulator on a substrate and having first and second electrodes, said method comprising the steps of: 
 providing a first cladding layer having a first refractive index on the substrate;    providing a self-assembled chromophore superlattice (SAS) having an intrinsic polar structure and a second refractive index on the first cladding layer;    providing a first glassy polymer having a third refractive index on the SAS, the third refractive index being approximately equal to the second refractive index at a predetermined wavelength; and    providing a second glassy polymer second cladding layer having a fourth refractive index on the SAS and about the first glassy polymer.    
     
     
         15 . A method as recited by  claim 14 , wherein the second and third refractive indices are greater than the first and fourth refractive indices.  
     
     
         16 . A method as recited by  claim 15 , wherein the second and third refractive indices are approximately equal to 1.54.  
     
     
         17 . A method as recited by  claim 14 , wherein the first glassy polymer is Cyclotene™ and wherein the third refractive index is approximately equal to 1.54.  
     
     
         18 . A method as recited by  claim 14 , wherein the second glassy polymer is Cytop™ and wherein the fourth refractive index is approximately equal to 1.34.