Photosensitive acrylate composition and waveguide device
View Patent ↗A photosensitive composition suitable for practical waveguide devices is provided. The photosensitive composition comprises at least one multifunctional acrylate prepared from a fluorinated multifunctional alcohol and at least one photoinitiator. The said composition has high photo contrast, high curing speed, controllable refractive index, low curing shrinkage, high thermo-optic coefficient, low volatility and high viscosity. A waveguide device is formed by patterning the photosensitive composition.
1. A waveguide device comprising a photosensitive composition wherein the photosensitive composition comprises a) at least one fluorinated non-urethane containing multifunctional acrylate prepared from at least one multifunctional alcohol, said alcohol being synthesized from a core molecule having at least two equivalents of hydroxyl-reacting functional groups and a fluorinated molecule having at least two hydroxyl groups; and b) at least one initiator, wherein the non-urethane containing multifunctional acrylate is prepared using the following reaction scheme:
wherein A is a fluorinated monomer or polymer having two hydroxyl groups, wherein Rf is a monomeric or polymeric perfluorinated alkylenediyl, alkylene oxide, arylenediyl, arylene oxide, or mixtures thereof, and R 1 and R 2 are monomeric or polymeric divalent moieties such as alkylenediyl, alkylene oxide, alkylene sulfide, arylenediyl, arylene oxide, arylene sulfide, siloxane or mixtures thereof; B is a multifunctional molecule wherein I is a multivalent radical, W stands for one equivalent of hydroxy-reacting functional group and n 1 is at least 2; C is the multifunctional alcohol product mixture from A and B, wherein L is an ether link and n 2 is at least 2; D is an acryloylation agent, wherein X is selected from OH, Cl or alkoxy; and E is the acrylate product mixture from C and D, wherein R 3 is H or CH 3 and n 3 is at least 2, wherein there are at least 2.5 equivalents of OH groups from A for every equivalent of hydroxyl-reacting group, W, from B.
2. The waveguide device of claim 1 , wherein the waveguide structure is patterned with an actinic radiation.
3. The waveguide device of claim 1 , wherein the waveguide structure is patterned with reactive ion etching (RIE).
4. A thermo-optic device comprising a waveguide structure of claim 1 and at least one resistive heater.
5. The waveguide device of claim 1 wherein said waveguide structure contains at least one optical grating element.
6. The waveguide device of claim 5 wherein said device comprises at least one resistive heater.
7. A method to produce a waveguide device having a light-transmitting structure formed on a substrate by forming a coating of the photosensitive composition of claim 1 on a substrate and patterning the coating with an actinic radiation.
8. A method to produce a waveguide device having a light-transmitting structure formed on a substrate comprising:
a) coating a layer of the composition of claim 1 on a substrate and exposing the layer to an actinic radiation to form a bottom cladding layer with a first refractive index;
b) coating a thin layer of the composition of claim 1 on top of the bottom cladding layer and patternwise exposing the thin layer to an actinic radiation through a photomask with a desired feature to form a latent image in a core layer;
c) removing the non-exposed portions in the core layer with an organic solvent to form a waveguide rib with a second refractive index that is higher than the first refractive index; and
d) coating a thin layer of the composition of claim 1 on top of the core layer and the bottom cladding layer and exposing the layer of the third composition to an actinic radiation to form a top cladding layer with a third refractive index that is lower than the second refractive index.
9. A waveguide device fabricated using the method of claim 8 .
10. The waveguide device of claim 9 , wherein the first refractive index=the third refractive index.