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1. WO2020112709 - FAST OPTICAL SWITCH

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

CLAIMS:

1 . An optical switch for a liquid crystal device comprising in sequence:

a first transparent substrate;

a first transparent electrode;

a first alignment layer;

a first liquid crystal film comprising a first antiferroelectric liquid crystal doped with a first dichroic dye;

a second liquid crystal film comprising a second antiferroelectric liquid crystal doped with a second dichroic dye;

optionally a second alignment layer;

a second transparent electrode; and

a second transparent substrate.

2. The optical switch of claim 1 , wherein the first liquid crystal film and the second liquid crystal film are aligned perpendicular to each other.

3. The optical switch of claim 1 , wherein the first liquid crystal film and the second liquid crystal film are smectic layers.

4. The optical switch of claim 1 , wherein the first antiferroelectric liquid crystal and the second antiferroelectric liquid crystal are the same.

5. The optical switch of claim 1 , wherein the first dichroic dye and the second dichroic dye are the same.

6. The optical switch of claim 1 , wherein the first antiferroelectric liquid crystal and the second antiferroelectric liquid crystal have a tilt angle in the range of about 40° to about 50°.

7. The optical switch of claim 6, wherein the tilt angle is about 45°.

8. The optical switch of claim 1 , wherein the switch is switchable in less than 1 millisecond.

9. The optical switch of claim 1 , wherein the switch is switchable in less than 200 microseconds.

10. A device comprising the optical switch of claim 1.

11. The device of claim 10, wherein the normal state is a dark state.

12. The device of claim 10, wherein the normal state is a bright state.

13. The device of claim 10, wherein the device is a privacy window, a refrigerator, an oven, a microwave, a windshield, or goggles.

14. A method for switching an electronic device from a first state to a second state, the method comprising:

applying an electric field to the electronic device;

wherein the electronic device comprises:

a first transparent substrate;

a first transparent electrode;

a first alignment layer;

a first liquid crystal film comprising a first antiferroelectric liquid crystal doped with a first dichroic dye;

a second liquid crystal film comprising a second antiferroelectric liquid crystal doped with a second dichroic dye;

optionally a second alignment layer;

a second transparent electrode; and

a second transparent substrate.

15. The method of claim 14, wherein the first state is a bright state and the second state is a dark state.

16. The method of claim 14, wherein the first state is a dark state and the second state is a bright state.

17. The method of claim 14, wherein electric field comprises a square wave AC field having an amplitude greater than about 2 V/pm and a frequency in the range of about 100 Hz to about 500 Hz.

18. The method of claim 14, wherein the first antiferroelectric liquid crystal and the second antiferroelectric liquid crystal have a tilt angle of about 45°.

19. The method of claim 14, wherein the switching occurs in a time period of less than 1 millisecond.

20. A method of forming an optical switch comprising:

sandwiching a first liquid crystal film and a second liquid crystal film between two transparent substrates;

wherein both the first liquid crystal film and the second liquid crystal film comprise an antiferroelectric liquid crystal doped with a dichroic dye; and

wherein the first liquid crystal film and the second liquid crystal film are aligned perpendicular to each other.