High-speed wide field-of-view electro-optic system and method

Patent metadata

Field	Value
Publication number	US-9817253-B2
Application number	US-201514747084-A
Country	US
Kind code	B2
Filing date	Jun 23, 2015
Priority date	Jul 8, 2014
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

An electro-optic modulator comprising at least one nanodisordered potassium tantalate niobate crystal; first and second conductors operatively connected to the nanodisordered potassium tantalate niobate crystal adapted to be connected to a voltage source to modulate light passing there through; whereby light is modulated by passing through the nanodisordered potassium tantalate niobate crystal. A method for modulating light comprising providing at least one at least one nanodisordered potassium tantalate niobate crystal; providing first and second conductors operatively connected to the nanodisordered potassium tantalate niobate crystal adapted to be connected to a voltage source to modulate light passing there through; providing an interrogating light beam striking at least one nanodisordered potassium tantalate niobate crystal; modulating light passing through the nanodisordered potassium tantalate niobate crystal; and receiving a modulated light beam.

First claim

What is claimed is:

1. An electro-optic system comprising:
a plurality of nanodisordered potassium tantalate niobate crystals;
first and second conductors configured to connect the nanodisordered potassium tantalate niobate crystals in series and adapted to be connected to drive circuitry to modulate light passing therethrough;
a retroreflector that reflects the modulated light through the array of nanodisordered potassium tantalate niobate crystals;
whereby light is intensity or phase modulated through the nanodisordered potassium tantalate niobate crystals in accordance with the voltage produced by the drive circuitry.

2. The system of claim 1 where the light passing through the plurality of potassium tantalate niobate crystals comprises an interrogation beam emitted by a light source and wherein the light reflected by the retroreflector comprises a phase or intensity modulated beam which is received by a receiver.

3. The system of claim 1 wherein the system is a free space modulator and further comprising polarizers configured to provide an intensity modulator.

4. The system of claim 1 wherein prior to operation the temperature of the plurality of nanodisordered potassium tantalate niobate crystals is reduced to the Curie temperature, causing them to become nanodisordered, in order to realize a higher electro-optic Kerr coefficient; the Curie temperature corresponding to the temperature at which the permittivity and Kerr coefficients reach a maximum value, such that the electro-optic Kerr coefficient can be substantially enhanced due to the nanodisordered effect in KTN crystals and the half-wave driving voltage can be correspondingly reduced.

5. The system of claim 1 wherein the plurality of nanodisordered potassium tantalate niobate crystals operates as a phase or intensity modulator that is oriented so as to modulate an interrogation beam and transmit the modulated interrogation beam to the retroreflector, and wherein said retroreflector is oriented so as to reflect the modulated interrogation beam through the nanodisordered potassium tantalate niobate crystals to a receiver.

6. The system of claim 1 further comprising drive circuitry that operates to produce an input signal such that the voltage of the input signal causes the nanodisordered potassium tantalate niobate crystals to shutter the interrogation light passing therethrough, resulting in a modulated interrogation beam.

7. The system of claim 1 wherein the system is a high-speed, wide field-of-view, large aperture shutter that is configured to operate as a free-space modulator for high-speed, long distance line-of-sight laser communications.

8. An electro-optic modulator comprising:
a plurality of nanodisordered potassium tantalate niobate crystals; the nanodisordered potassium tantalate niobate crystals becoming nanodisordered by reducing the temperature of the nanodisordered potassium tantalate niobate crystals to the Curie temperature to realize a higher electro-optic Kerr coefficient such that the driving voltage can be correspondingly reduced; the Curie temperature corresponding to the temperature at which the permittivity and electro optic Kerr coefficient reaches a maximum value;
first and second conductors operatively connected to the plurality of nanodisordered potassium tantalate niobate crystals adapted to be connected to a voltage source to modulate light passing therethrough;
a retroreflector for reflecting light back through the plurality of nanodisordered potassium tantalate niobate crystals;
whereby light is modulated by passing through the plurality of nanodisordered potassium tantalate niobate crystals.

9. The modulator of claim 8 further comprising an enclosure comprising windows allowing light to enter while operating to prevent condensation of water on the plurality of nanodisordered potassium tantalate niobate crystals; and wherein the retroreflector that reflects the modulated light comprises a prism.

10. The modulator of claim 9 further comprising a receiver and wherein light passing through the plurality of potassium tantalate niobate crystals comprises a light beam emitted by a light source and wherein the light reflected by the retroreflector comprises a phase or intensity modulated beam that is received by the receiver.

11. The modulator of claim 8 , wherein the modulator is a high-speed, wide field-of-view, large aperture shutter that is configured to operate as a free-space modulator for high-speed, long distance line-of-sight laser communications.

12. The modulator of claim 8 configured as a phase modulator wherein the intensity of the light passing through remains substantially constant but the phase of two components of the electric field with respect to the y and z directions is modulated.

13. An electro-optic modulator comprising:
an array of nanodisordered potassium tantalate niobate crystals; the potassium tantalate niobate crystals becoming nanodisordered by reducing the temperature of the nanodisordered potassium tantalate niobate crystal to the Curie temperature to realize a higher electro-optic Kerr coefficient such that the driving voltage can be correspondingly reduced; the Curie temperature corresponding to the temperature at which the permittivity and electro optic Kerr coefficient reaches a maximum value;
first and second conductors operatively connected to the array of nanodisordered potassium tantalate niobate crystals adapted to be connected to a voltage source comprising drive circuitry operating to modulate the light passing through the array of potassium tantalate niobate crystals.

14. The modulator of claim 13 further comprising at least one polarizer and wherein the array of nanodisordered potassium tantalate niobate crystals operates as an intensity modulator that is oriented so as to modulate an incoming beam and transmit a modulated beam to a receiver.

15. An electro-optic modulator comprising:
a plurality of nanodisordered potassium tantalate niobate crystals arranged in an array;
first and second conductors configured to connect the plurality of nanodisordered potassium tantalate niobate crystals in series and adapted to be connected to a voltage source to modulate light passing therethrough; the first and second conductors configured such that during operation when a high voltage is applied across the first and second conductors the voltage drops evenly;
a housing surrounding the modulator and a thermoelectric heat exchanger configured to maintain the temperature of the modulator within a predetermined range;
whereby light is modulated by passing through the nanodisordered potassium tantalate niobate crystals.

16. An electro-optic modulator comprising:
a plurality of nanodisordered potassium tantalate niobate crystals arranged in an array; the nanodisordered potassium tantalate niobate crystals becoming nanodisordered by reducing the temperature of the nanodisordered potassium tantalate niobate crystal to the Curie temperature to realize a higher electro-optic Kerr coefficient such that the driving voltage can be correspondingly reduced; the Curie temperature corresponding to the temperature at which the permittivity and electro optic Kerr coefficient reaches a maximum value;
first and second conductive strips placed between and connecting the plurality of nanodisordered potassium tantalate niobate crystals in series and configured such that during operation when a high voltage is applied across the first and second conductive strips the voltage drops evenly across conductive strips;
whereby light is modulated by passing through the nanodisordered potassium tant

Assignees

• U S Army Res Laboratory Attn: Rdrl-Loc-I
• Us Army

Inventors

• Hoffman Robert C
• Yin Shizhuo

Classifications

• G02F1/0316

  Electrodes · CPC title

• G02F1/0311

  Structural association of optical elements, e.g. lenses, polarizers, phase plates, with the crystal · CPC title

• G02F1/0018

  Electro-optical materials · CPC title

• G02B5/122

  cube corner, trihedral or triple reflector type · CPC title

• G02F1/0327 Primary

  Operation of the cell; Circuit arrangements (G02F1/05 takes precedence) · CPC title