US4779959A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid crystal electro-optic modulator in a fabry-perot interferometer
Assignee: UK Secretary of State for Defence
•
Filing: 1987-09-04
•
Granted: 1988-10-25
•
Expires: 2007-09-04
Abstract
Abstract An electro-optic modulator consists of a Fabry-Perot etalon containing intra-cavity liquid crystal material between mirror layers. Each mirror bears a respective rubbed polyimide layer, which provides homogeneous alignment of the liquid crystal molecules. The mirror layers are connected to a bias voltage source, which provide an electrical bias variable between two values both above the threshold for refractive index sensitivity to applied voltage. For nematic materials, this is the Freedricks threshold or transition. The bias variation provides optical modulation of the etalon transmission with a time constant which is much shorter than devices switching between voltages either side of the threshold.
Inventors
- 👤 Frances C. Saunders
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:55
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/21; G02F1/216; G02F1/13; G02F1/137; G02F1/139; G02F1/1393; G02F1/1396; G02F1/1397; G02F1/141; G02F2203/00; G02F2203/05; G02F2203/055
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
55 words
An electro-optic modulator including a Fabry-Perot etalon containing intra-cavity liquid crystal material and biasing means for applying a bias voltage to the material, the bias voltage being variable between two values both of which are above an etalon threshold voltage V T above which the liquid crystal material refractive index is sensitive to electrical bias.
Claim 2
Dependent Claim
55 words
An electro-optic modulator including a Fabry-Perot etalon containing intra-cavity liquid crystal material and biasing means for applying a bias voltage to the material, the bias voltage being variable between two values both of which are above an etalon threshold voltage V T above which the liquid crystal material refractive index is sensitive to electrical bias.
Claim 3
Dependent Claim
40 words
A modulator according to claim 1 wherein the bias voltage is variable between two values of which are in the range 2 V T to 20 V T , and between which the etalon exhibits a monotonically changing optical transmission.
Claim 4
Dependent Claim
27 words
A modulator according to claim 2 wherein the bias voltage is variable between two voltages both in the range 5 V T to 10 V T .
Claim 5
Dependent Claim
39 words
A modulator according to claim 2 wherein the etalon has a cavity width in the range 5 to 20 microns and the liquid crystal material is nematic with positive dielectric anisotropy and homogeneous alignment relative to internal etalon walls.
Claim 6
Dependent Claim
50 words
A modulator according to claim 2 wherein the etalon has a cavity width in the range 5 to 20 microns and the liquid crystal material has negative dielectric anisotropy and a tilted homeotropic alignment inclined to the perpendicular to etalon walls at an angle in the range 2° to 10°.
Claim 7
Dependent Claim
34 words
A modulator according to claim 2 wherein the etalon has a cavity width in the range 5 to 20 microns and the liquid crystal material has positive dielectric anisotropy and has hybrid molecular alignment.
Claim 8
Dependent Claim
35 words
A modulator according to claim 2 wherein the etalon has a cavity width in the range 5 to 20 microns and the liquid crystal material has a positive dielectric anisotropy and a π-cell alignment twist.
Claim 9
Dependent Claim
34 words
A modulator according to claim 2 wherein the etalon has a cavity width in the range 5 to 20 microns and the liquid crystal material has low birefringence and has a 2π alignment twist.
Claim 10
Dependent Claim
32 words
A modulator according to claim 2 wherein the etalon has a cavity width in the range 1 to 6 microns and the liquid crystal material is a ferroelectric smectic with homogeneous alignment.
Claim 11
Independent Claim
92 words
A method of obtaining optical modulation including the steps of: (1) providing a Fabry-Perot etalon containing intra-cavity liquid crystal material and bias electrodes arranged to bias the material, (2) passing light through the etalon cavity, the light having an intensity below that at which optical bistability would occur in the liquid crystal material, and (3) applying bias voltage to the bias electrodes, the bias voltage being variable between two values both of which are above an etalon threshold voltage above which the liquid crystal material refractive index is sensitive to electrical bias.
Claim 12
Independent Claim
92 words
A method of obtaining optical modulation including the steps of: (1) providing a Fabry-Perot etalon containing intra-cavity liquid crystal material and bias electrodes arranged to bias the material, (2) passing light through the etalon cavity, the light having an intensity below that at which optical bistability would occur in the liquid crystal material, and (3) applying bias voltage to the bias electrodes, the bias voltage being variable between two values both of which are above an etalon threshold voltage above which the liquid crystal material refractive index is sensitive to electrical bias.
References Cited (Backward Citations)
US32521A
Cited
US3694053A
Cited
US3891307A
Cited
USRE32521E
Cited
USRE32521F1
Cited
US4272195A
Cited
US4444469A
Cited
US4566758A
Cited
US4595292A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-10-25 | 1992-04-25 | 1992-10-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-25 | 1996-04-25 | 1996-10-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-25 | 2000-04-25 | 2000-10-25 | $7700.00 | Window Closed / Lapsed |