Electro-optically tunable filter

• US 20020009251A1
• Filed: 03/30/2001
• Published: 01/24/2002
• Est. Priority Date: 03/31/2000
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Byrne, Dale M.
• Granted Patent: US 6,724,950 B2
• Time in Patent Office: Days
• US Class Current: 385/2
• CPC Class Codes: G02F 1/0316 Electrodes
• CPC Class Codes: G02F 2201/122 having a particular pattern
• CPC Class Codes: G02F 2201/305 diffraction grating
• CPC Class Codes: G02F 2203/055 wavelength filtering

Abstract

The present invention provides configurations for an electro-optically tunable filter. The filter includes an electro-optical crystal, at least one electrically conductive mesh screen, at least one electrode and a voltage source. In one embodiment, an electrical voltage passes from a source to a mesh screen contacting the crystal, through the crystal and an electrode on the crystal'"'"'s opposite end. The mesh screen creates a narrow bandpass. The optical properties of the mesh screen-crystal combination are determined partially by the refractive index of the crystal when a voltage is applied to the mesh screen. Variable voltages change the refractive index of the crystal, creating varying spectral positions of the filter. Application of a voltage between the mesh screen and the electrode creates a field internal to the crystal that changes its refractive index, allowing it to be tunable in the bandpass location thereby affecting a passing light signal.

Claims

1. A tunable electro-optical filter, comprising:

an electro-optical crystal having an input portion and an output portion, the output portion diametric to the input portion, wherein the electro-optical crystal changes its refractive index when an electric field is applied to it;

an electrode covering and in electrical contact with the output portion of the electro-optical crystal; and

an electrically conductive mesh filter covering and in electrical contact with the input portion of the electro-optical crystal, wherein the electrically conductive mesh filter creates a narrow bandpass and carries electrical voltage to and through the electro-optical crystal to a voltage source.

2. The tunable electro-optical filter of claim 1 wherein optical properties of the electrically conductive mesh filter are determined partially by the refractive index of the electro-optical crystal once a voltage is applied to the electrically conductive mesh filter and the electrode.

3. The tunable electro-optical filter of claim 1 wherein the refractive index of the electro-optical crystal can be changed with the application of variable voltages to the electrically conductive mesh filter, thereby creating varying spectral positions of the electrically conductive mesh filter.

4. The tunable electro-optical filter of claim 1 wherein the voltage source is in electrical contact with the electrically conductive mesh filter and the electrode.

5. The tunable electro-optical filter of claim 1 wherein the voltage source is variable.

6. The tunable electro-optical filter of claim 1 wherein a thin film coating is applied to the electro-optical crystal.

7. The tunable electro-optical filter of claim 1 wherein the electrode comprises a semi-transparent conductive film.

8. The tunable electro-optical filter of claim 1 wherein the electrode comprises a thin metal sheet with a centered opening.

9. The tunable electro-optical filter of claim 1 further comprising a second electrically conductive mesh filter covering the electrode.

10. A tunable electro-optical filter, comprising:

an electro-optical crystal having an input portion and an output portion, the output portion diametric to the input portion, wherein the electro-optical crystal changes its refractive index when an electric field is applied to it;

an electrode covering and in electrical contact with the output portion of the electro-optical crystal; and

an electrically conductive mesh filter covering and in electrical contact with the input portion of the electro-optical crystal, wherein the electrically conductive mesh filter creates a narrow bandpass and carries electrical voltage to and through the electro-optical crystal to a voltage source, wherein the voltage source is in electrical contact with the electrically conductive mesh filter and the electrode.

11. The tunable electro-optical filter of claim 10 wherein optical properties of the electrically conductive mesh filter are determined partially by the refractive index of the electro-optical crystal once a voltage is applied to the electrically conductive mesh filter and the electrode.

12. The tunable electro-optical filter of claim 10 wherein the refractive index of the electro-optical crystal can be changed with the application of variable voltages to the electrically conductive mesh filter, thereby creating varying spectral positions of the electrically conductive mesh filter.

13. The tunable electro-optical filter of claim 10 wherein the voltage source is variable.

14. A method of producing a narrow band optical signal from a wider band optical signal, comprising;

applying a voltage to a mesh and an electrode, wherein the mesh further comprises a filter comprised of electrically conductive material and the mesh is disposed in electrical contact on a side of an electro-optical crystal;

providing a light signal through the mesh thereby allowing a light signal to pass through the mesh and the electro-optical crystal, wherein the light signal is transformed into a narrow bandpass optical signal after passing through the mesh and the crystal; and

providing the narrow bandpass optical signal to a measuring device.

15. The method of claim 14 wherein application of a voltage between the mesh and the electrode creates a field internal to the electro-optical crystal that will change the refractive index of the electro-optical crystal thereby enabling it to be tunable in the bandpass location.

16. The method of claim 14 wherein the voltage applied to the electro-optical crystal is variable.

17. A tunable electro-optical filter, comprising:

an electro-optical crystal having in input portion and an output portion, the output portion diametric to the input portion, wherein the electro-optical crystal changes its refractive index when an electric field is applied to it;

an electrically conductive mesh filter covering and in electrical contact with the input portion of the electro-optical crystal, wherein the electrically conductive mesh filter creates a narrow bandpass;

a first electrode covering and in electrical contact with the electro-optical crystal and contiguous to the electrically conductive mesh filter;

a second electrode covering and in electrical contact with the electro-optical crystal, contiguous to the electrically conductive mesh filter and diametric to the first electrode; and

a voltage source in electrical contact with the first electrode and the second electrode.

18. The tunable electro-optical filter of claim 17 wherein the voltage source is variable.

19. The tunable electro-optical filter of claim 17 wherein a thin film coating is applied to the electro-optical crystal.

20. The tunable electro-optical filter of claim 17 wherein the first electrode and the second electrode each comprises a conductive continuous solid thin film.

21. The tunable electro-optical filter of claim 17 wherein the first electrode and the second electrode each comprises a thin metal sheet.