Optical devices made from radiation curable fluorinated compositions

Abstract

The invention provides organic optical waveguide devices which employ perfluoropolymeric materials having low optical loss and low birefringence. An optical element has a substrate; a patterned, light transmissive perfluoropolymer core composition; and a light reflecting cladding composition on the pattern of the core. Writing of high-efficiency waveguide gratings is also disclosed.

We claim:  
     
         1 . A method of making an optical element comprising: 
 a) applying a core photopolymerizable composition to a support to form a core photopolymerizable composition layer, said core photopolymerizable composition including at least one photoinitiator and at least one core photopolymerizable monomer, oligomer, or polymer having at least one photopolymerizable group, said core photopolymerizable monomer, oligomer, or polymer including a perfluorinated substituent;    b) imagewise exposing the core photopolymerizable composition layer to sufficient actinic radiation to effect the at least partial polymerization of an imaged portion and to form at least one non-imaged portion of said core photopolymerizable composition layer;    c) removing said at least one non-imaged portion without removing said imaged portion, thereby forming a light transmissive patterned core from said imaged portion;    d) applying an upper cladding polymerizable composition onto the patterned core; and    e) at least partially curing said upper cladding composition, wherein said upper cladding and the core-interfacing surface of said support have a lower refractive index than said core.    
     
     
         2 . The method of  claim 1  wherein said perfluorinated substituent is selected from the group consisting of 
 —(CF 2 ) x —,  
 —CF 2 O—[(CF 2 CF 2 O) m (CF 2 O) n ]—CF 2 —, and  
 —CF(CF 3 )O(CF 2 ) 4 O[CF(CF 3 )CF 2 O] p CF(CF 3 )—,  
 where x is 1-10, m and n designate the number of randomly distributed perfluoroethyleneoxy and perfluoromethyleneoxy backbone repeating subunits, respectively, and p designates the number of —CF(CF 3 )CF 2 O—backbone repeating subunits.  
 
     
     
         3 . The method of  claim 2  wherein said perfluorinated substitutent is —CF 2 O—[(CF 2 CF 2 O) m (CF 2 O) n ]—CF 2 — and the ratio m/n varies from about 0.5 to about 1.4.  
     
     
         4 . The method of  claim 3  wherein the ratio m/n is about 1 and the molecular weight of the core photopolymerizable monomer, oligomer, or polymer lies between about 2000 and about 2800.  
     
     
         5 . The method of  claim 1  wherein the photopolymerizable group is an epoxy or ethylenically unsaturated group.  
     
     
         6 . The method of  claim 5  wherein said epoxy group is selected from the group consisting of  
       
         
           
           
               
               
           
         
       
     
     
         7 . The method of  claim 5  wherein the ethylenically unsaturated group is selected from the group consisting of vinyl ethers, acrylates, and methacrylates.  
     
     
         8 . The method of  claim 1  wherein the core photopolymerizable monomer, oligomer, or polymer has the structure 
       A—R—R f —R′—A where    R and R′ are divalent or trivalent connecting groups selected from the group consisting of alkyl, aromatic, ester, ether, amide, amine, or isocyanate groups;    said photopolymerizable group, A, is selected from the group consisting of                        CY 2 ═C(X)COO—, and    CH 2 ═CHO—;      where 
 Y=H or D, and  
 X=H, D, F, Cl or CH 3 ; and  
   said perfluorinated substitutent, R f , is selected from the group consisting of 
 —(CF 2 ) x ,  
 —CF 2 O—[(CF 2 CF 2 O) m (CF 2 O) n ]—CF 2 —, and  
 —CF(CF3)O(CF 2 ) 4 O[CF(CF 3 )CF 2 O] p CF(CF 3 )—,  
 where x is 1-10, m and n designate the number of randomly distributed perfluoroethyleneoxy and perfluoromethyleneoxy backbone repeating subunits, respectively, and p designates the number of —CF(CF 3 )CF 2 O— backbone repeating subunits.  
   
     
     
         9 . The method of  claim 8  wherein the connecting group R is —CH 2 — or —CH 2 C(A)HCH 2 OCH 2 — and the connecting group R′ is —CH 2 — or —CH 2 OCH 2 C(A)HCH 2 —.  
     
     
         10 . The method of  claim 1  wherein said upper cladding polymerizable composition includes at least one upper cladding photoinitiator and at least one upper cladding photopolymerizable monomer, oligomer, or polymer having at least one upper cladding photopolymerizable group, said upper cladding photopolymerizable monomer, oligomer, or polymer including an upper cladding perfluorinated substituent.  
     
     
         11 . The method of  claim 1  wherein said support includes a silicon wafer substrate.  
     
     
         12 . The method of  claim 1  where said support is a laminate formed by: 
 f) applying a coating of a lower cladding polymerizable composition to a substrate, said lower cladding composition including at least one lower cladding photoinitiator and at least one lower cladding photopolymerizable monomer, oligomer, or polymer having at least one lower cladding photopolymerizable group, said lower cladding photopolymerizable monomer, oligomer, or polymer including a lower cladding perfluorinated substituent; and  
 g) at least partially curing said lower cladding composition to form a lower cladding layer.  
 
     
     
         13 . The method of  claim 12  wherein said at least partial curing includes exposing said coating of a lower cladding polymerizable composition to heat and/or actinic radiation.  
     
     
         14 . The method of  claim 1  wherein said core photopolymerizable composition includes a first photopolymerizable monomer, oligomer, or polymer compound and a second photopolymerizable monomer, oligomer, or polymer compound, both of which compounds include at least two photopolymerizable groups and a perfluorinated substituent.  
     
     
         15 . The method of  claim 14  wherein the difference between the functionality of said second photopolymerizable compound and said first photopolymerizable compound is at least one.  
     
     
         16 . The method of  claim 15  wherein said second photopolymerizable compound is a tetra-functional or higher functionality compound and said first photopolymerizable compound is a di-functional or higher functionality compound.  
     
     
         17 . The method of  claim 16  wherein said first photopolymerizable compound is a di-acrylate compound and said second photopolymerizable compound is a tetra-acrylate compound.  
     
     
         18 . The method of  claim 15  wherein said core photopolymerizable composition comprises from about 40 to about 60 wt. % of said first photopolymerizable compound and from about 40 to about 60 wt. % of said second photopolymerizable compound based on the weight of said core photopolymerizable composition.  
     
     
         19 . The method of  claim 18  wherein said core photopolymerizable composition comprises about 50 wt. % of said first photopolymerizable compound and about 50 wt. % of said second photopolymerizable compound based on the total weight of said first and second core photopolymerizable compounds.  
     
     
         20 . The method of  claim 1  further comprising: 
 1) exposing said at least partially cured core to light through a phase mask to write a grating in said core; and  
 2) thereafter sustantially fully curing said core with actinic radiation, heat, or both heat and actinic radiation.  
 
     
     
         21 . A light-guiding optical element comprising: 
 a) an organic upper cladding layer;    b) an organic light transmissive core comprising a fluoropolymer including at least one perfluorinated substituent;    c) an organic lower cladding layer; and    d) a substrate.    
     
     
         22 . The optical element of  claim 21  wherein said perfluorinated substituent is selected from the group consisting of 
 —(CF 2 ) x ,  
 —CF 2 O—[(CF 2 CF 2 O) m (CF 2 O) n ]—CF 2 —, and  
 —CF(CF 3 )O(CF 2 ) 4 O[CF(CF 3 )CF 2 O] p CF(CF 3 )—,  
 where x is 1-10, m and n designate the number of randomly distributed perfluoroethyleneoxy and perfluoromethyleneoxy backbone repeating subunits, respectively, and p designates the number of —CF(CF 3 )CF 2 O— backbone repeating subunits.  
 
     
     
         23 . The optical element of  claim 22  wherein the fluoropolymer is produced from a core photopolymerizable composition including the compound  
       
         
           
           
               
               
           
         
       
       where m and n designate the number of randomly distributed perfluoroethyleneoxy and perfluoromethyleneoxy backbone repeating subunits, respectively, and the ratio m/n falls within the range of about 0.5 to about 1.4.  
     
     
         24 . The optical element of  claim 23  wherein said core photopolymerizable composition further includes the compound 
       CH 2 ═CHCO 2 CH 2 (CF 2 CF 2 O) m (CF 2 O) n CF 2 CH 2 O 2 CCH=CH 2   
     
     
         25 . The optical element of  claim 22  wherein the optical loss of 1550 nm light through said light transmissive core is less than 0.75 dB/cm.  
     
     
         26 . The optical element of  claim 25  wherein the optical loss of 1550 nm light through said light transmissive core is less than 0.5 dB/cm.  
     
     
         27 . The optical element of  claim 21  wherein the glass transition point of said upper cladding layer and lower cladding layer is about 40° C. or less and that of the light transmissive core is about 50° C. or less.  
     
     
         28 . The optical element of  claim 27  wherein the glass transition point of said light transmissive core is less than 0° C.  
     
     
         29 . A method of transmitting optical information comprising: 
 a) providing an information-bearing optical signal; and    b) passing said optical signal through a light-transmissive polymer formed from a perfluorinated radiation curable monomer, oligomer, or polymer having at least one radiation curable group selected from the group consisting of epoxy or ethylenically unsaturated group.    
     
     
         30 . The method of  claim 29  wherein said signal is at a wavelength of about 1550 nm.  
     
     
         31 . The method of  claim 29  further comprising passing said optical signal through a diffraction grating written in said light-transmissive polymer.  
     
     
         32 . A method of making an optical element comprising: 
 a) applying a photopolymerizable composition to a support to form a photopolymerizable composition layer, said photopolymerizable composition including an effective amount of at least one photoinitiator and at least one photopolymerizable monomer, oligomer, or polymer having at least one photopolymerizable group, said photopolymerizable monomer, oligomer, or polymer including a perfluorinated substituent;    b) at least partially curing said layer;    c) forming a core by a method selected from the group consisting of reactive ion etching, micro replication, direct laser writing, and laser ablation    d) applying an upper cladding polymerizable composition onto said core; and    e) at least partially curing said upper cladding composition to form an upper cladding.    
     
     
         33 . The method of  claim 32  wherein 
 said polymerizable composition is a core polymerizable composition; and forming said core includes 
 1) protecting a region of said layer with a reactive ion etching-resistant material; and  
 2) removing unprotected regions of said at least partially cured layer to form a raised rib core.  
 
 
     
     
         34 . The method of  claim 32  wherein 
 said polymerizable composition is a lower cladding polymerizable composition; and  
 forming said core includes  
 1) protecting a region of said layer with a reactive ion etching-resistant material; and  
 2) removing unprotected regions of said at least partially cured layer to form a trench in said lower cladding layer.  
 
     
     
         35 . The method of  claim 34  further comprising applying a core polymerizable composition to said trench and at least partially curing said core composition.  
     
     
         36 . The method of  claim 35  further comprising applying an upper cladding composition to said core and at least partially curing said upper cladding composition.  
     
     
         37 . The method of  claim 32  wherein said photopolymerizable composition is applied to an at least partially cured lower cladding layer in contact with said support.  
     
     
         38 . The method of  claim 32  wherein said photopolymerizable composition is applied in direct contact with said support.  
     
     
         39 . The method of  claim 32  further comprising applying an electrode to said upper cladding in alignment with said core.  
     
     
         40 . The method of  claim 32  wherein said perfluorinated substituent is selected from the group consisting of 
 —(CF 2 ) x —,  
 —CF 2 O—[(CF 2 CF 2 O) m (CF 2 O) n ]—CF 2 —, and  
 —CF(CF 3 )O(CF 2 ) 4 O[CF(CF 3 )CF 2 O] p CF(CF 3 )—,  
 where x is 1-10, m and n designate the number of randomly distributed perfluoroethyleneoxy and perfluoromethyleneoxy backbone repeating subunits, respectively, and p designates the number of —CF(CF 3 )CF 2 O— backbone repeating subunits.  
 
     
     
         41 . The method of  claim 32  wherein the said polymerizable monomer, oligomer, or polymer has the structure 
       A—R—R f —R′—A where    R and R′ are divalent or trivalent connecting groups selected from the group consisting of alkyl, aromatic, ester, ether, amide, amine, or isocyanate groups;    said polymerizable group, A, is selected from the group consisting of                        CY 2 ═C(X)COO—, and    CH 2 ═CHO—;      where 
 Y=H or D, and  
 X=H, D, F, Cl or CH 3 ; and  
   said perfluorinated substitutent, R f , is selected from the group consisting of 
 —(CF 2 ) x —,  
 —CF 2 O—[(CF 2 CF 2 O) m (CF 2 O) n ]—CF 2 —, and  
 —CF(CF 3 )O(CF 2 ) 4 O[CF(CF 3 )CF 2 O] p CF(CF 3 )—,  
   where x is 1-10, m and n designate the number of randomly distributed perfluoroethyleneoxy and perfluoromethyleneoxy backbone repeating subunits, respectively, and p designates the number of —CF(CF 3 )CF 2 O— backbone repeating subunits.    
     
     
         42 . The method of  claim 41  wherein the connecting group R is —CH 2 — or —CH 2 C(A)HCH 2 OCH 2 — and the connecting group R′ is —CH 2 — or —CH 2 OCH 2 C(A)HCH 2 —.  
     
     
         43 . A composition comprising: 
 a) a first photocurable multifunctional perfluorinated compound having a first functionality;    b) a second photocurable multifunctional perfluorinated compound having a second functionality, wherein the difference between said second functionality and said first functionality is at least one; and    c) an effective amount of a photoinitiator.    
     
     
         44 . The composition of  claim 43  wherein each of said first and second compounds is an acrylate.  
     
     
         45 . The composition of  claim 44  wherein from about 40 to about 60 wt. % of said composition is said first compound and from about 40 to about 60 wt. % of said composition is said second compound.  
     
     
         46 . The composition of  claim 43  wherein said difference is at least two.  
     
     
         47 . The composition of  claim 43  wherein said first compound is a di-acrylate and said second compound is a tetra-acrylate.  
     
     
         48 . The composition of  claim 43  wherein said first compound is octafluorohexanediol di-acrylate.  
     
     
         49 . The composition of  claim 48  wherein said second compound is a polyether tetra-acrylate.  
     
     
         50 . A waveguide grating made from the composition of claim  42 .