Active optical switch system with anti-wetting coating
An optical switch includes a substrate with a waveguide-coupling area and a fluid channel with an anti-wetting layer on a first surface. First and second fluids are on the anti-wetting layer in the fluid channel and at least one fluid is selectively movable relative to the waveguide-fluid coupling area. A fluidic driving mechanism has at least one electrode positioned to apply an electric field to at least one of the fluids in the fluid channel and is capable of moving at least one of the fluids in the fluid channel. The anti-wetting layer has an alkyl silane coating, which includes alkyl silane molecules covalently bonded to the first surface of the fluid channel.
1. An active optical switch system, comprising:
a substrate having a waveguide-fluid coupling region;
a fluid channel adjacent the substrate, the fluid channel having a first surface, the first surface being a silicon surface;
an anti-wetting layer on the first surface of the fluid channel;
at least a first fluid within the fluid channel and contacting the anti-wetting layer, the first fluid being a first liquid;
wherein the anti-wetting layer comprises an alkyl silane coating, the alkyl silane coating comprising alkyl silane molecules covalently bonded to the first surface of the fluid channel.
2. The system of claim 1 , further comprising a second fluid in the fluid channel, and a fluidic driving mechanism for moving at least one of the first and second fluids within the fluid channel, the fluidic driving mechanism comprising at least one electrode positioned to apply an electric field to at least the first fluid in the fluid channel.
3. The system of claim 1 , wherein the alkyl silane molecules comprise unbranched alkyl groups.
4. The system of claim 1 , wherein the alkyl silane molecules comprise alkyl groups that are at least partially fluorinated.
5. The system of claim 1 , wherein the alkyl silane molecules comprise alkyl groups having between one and eighteen carbon atoms.
6. A method of making an optical switch, comprising:
providing a substrate with a fluid-optical coupling area and a waveguide proximate the fluid-optical coupling area;
providing a fluid channel proximate the fluid-optical coupling area and the substrate, the fluid channel having a first surface, the first surface being a silicon surface;
providing an alkyl silane, the alkyl silane having an alkyl group and a silicon atom with at least one active group;
reacting the alkyl silane with the first surface to covalently bond the alkyl silane to the first surface, thereby forming an alkyl silane anti-wetting coating on the first surface.
7. The method of claim 6 , wherein the alkyl silane anti-wetting coating is substantially a mono-layer of alkyl silane on the first surface.
8. The method of claim 6 , wherein the at least one active group comprises at least one of a halogen atom and an alkoxy group.
9. The method of claim 6 , wherein the alkyl group is unbranched.
10. The method of claim 6 , wherein the alkyl group is at least partially fluorinated.
11. The method of claim 6 , wherein the alkyl group comprises between one and eighteen carbon atoms.
12. The method of claim 6 , wherein, before reacting the alkyl silane with the first surface, the first surface comprises hydroxylated silicon.
13. The method of claim 6 , wherein reacting the alkyl silane comprises reacting the alkyl silane in a vapor phase with the first surface.
14. The method of claim 6 , wherein the alkyl silane is a fluorinated alkyl chlorosilane.
15. The method of claim 6 , wherein the alkyl silane is a fluorinated alkyl trichlorosilane.
16. The method of claim 15 , wherein the fluorinated alkyl chlorosilane is 1H,1H,2H,2H-perfluorodecyltrichlorosilane.
17. The method of claim 6 , wherein reacting the alkyl silane with the first surface comprises heating the first surface and the alkyl silane to a coating temperature between 40 and 300° C.
18. The method of claim 17 , wherein reacting the alkyl silane with the first surface further comprises maintaining the first surface and the alkyl silane at the coating temperature for between one to three hours.
19. The method of claim 6 , wherein reacting the alkyl silane with the first surface comprises reacting the alkyl silane in a liquid phase.
20. The method of claim 6 , wherein the alkyl silane comprises an alkoxy active group, and wherein reacting the alkyl silane with the first surface further comprises:
hydroxylating the alkyl silane in a first hydroxylating solution;
exposing the first surface to the hydroxylated alkyl silane;
rinsing the first surface; and
drying the first surface.
21. The method of claim 6 , wherein the alkyl silane comprises a chloro active group, and wherein reacting the alkyl silane with the first surface further comprises:
hydroxylating the alkyl silane in a first hydroxylating solution;
hydroxylating the alkyl silane;
exposing the first surface to the hydroxylated alkyl silane;
rinsing the first surface; and
drying the first surface.
22. An optical switch comprising:
a substrate having at least a first optical waveguide;
a fluid channel adjacent the substrate, the fluid channel containing a first fluid and a second fluid, at least one surface of the fluid channel being a silicon surface coated with an anti-wetting layer; and
wherein at least one of the first and second fluids are selectively movable within the fluid channel relative to a waveguide-fluid interaction region, an optical characteristic of the first waveguide being dependent on whether the first fluid or second fluid is located at the waveguide-fluid interaction region; and
wherein the anti-wetting layer comprises an alkyl silane coating, the alkyl silane coating comprising alkyl silane molecules covalently bonded to the at least one surface.