Dispersive precompensator for use in an electromagnetic radiation generation and detection system

• US 6,320,191 B1
• Filed: 02/25/1999
• Issued: 11/20/2001
• Est. Priority Date: 03/27/1998
• Status: Expired due to Term

• Current Assignee: Picometrix LLC (Luna Innovations, Inc.)
• Original Assignee: Picometrix LLC (Luna Innovations, Inc.)
• Inventors: Rudd, James V.
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): Israel, Andrew
• Application Number:
  US09/257,421
• Time in Patent Office: 999 Days
• Field of Search: 250/330, 250/341.1
• US Class Current: 250/341.1
• CPC Class Codes: G02B 6/2931 Diffractive element operating in reflection
• CPC Class Codes: G02B 6/29311 Diffractive element operating in transmission
• CPC Class Codes: G02B 6/29317 Light guides of the optical fibre type
• CPC Class Codes: G02B 6/29358 Multiple beam interferometer external to a light guide, e.g. Fabry-Pérot, etalon, VIPA plate, OTDL plate, continuous interferometer, parallel plate resonator G02B6/29347, G02B6/29349, G02B6/2935, G02B6/29361 take precedence; resonator evanescently coupled to light guide G02B6/29335
• CPC Class Codes: G02B 6/29373 utilising a bulk dispersive element, e.g. prism
• CPC Class Codes: G02B 6/29394 Compensating wavelength dispersion G02B6/29376 takes precedence; dispersion compensated optical transmission systems H04B10/2507
• CPC Class Codes: H01S 1/02 solid
• CPC Class Codes: H04B 10/25133 including a lumped electrical or optical dispersion compensator H04B10/2519, H04B10/2525 takes precedence
• CPC Class Codes: H04B 2210/254 before the transmission line, i.e. pre-compensation

Abstract

An electromagnetic radiation emitter which utilizes a precompensator, pulsed light signal, optical fiber cable, and a terahertz radiation generator. The present invention incorporates an optical precompensator to correct for the stretching of an optical signal as it travels through an optical fiber cable. The dispersion characteristics of the precompensator will be equal and opposite to the dispersion characteristics of the optical fiber cable, maintaining the fidelity of optical pulses as they travel through and exit the optical fiber cable striking a device that generates terahertz electromagnetic radiation.

Claims

1. A system for transmitting terahertz electromagnetic radiation, the system comprising:

an optical fiber for transmitting an optical pulse, wherein the optical pulse has a plurality of known original dimensions;

a precompensator in communication with the optical fiber for receiving the optical pulse and configured to provide a sufficient amount of dispersion to restore the plurality of known original dimensions that have been changed as the pulse propagates through the optical fiber; and

a terahertz transmitter having an antenna, wherein the transmitter is in communication with the precompensator for detecting the optical pulse and generating the terahertz electromagnetic radiation.

2. The system of claim 1 further comprising a terahertz receiver for detecting the terahertz electromagnetic radiation transmitted by the terahertz transmitter.

3. The system of claim 1, wherein said precompensator is a prism pair.

4. The system of claim 1, wherein said precompensator is a grism pair.

5. The system of claim 1, wherein said precompensator is a three bounce grating system arrangement.

6. The system of claim 1, wherein said precompensator is a Treacy Grating pair.

7. The system of claim 1, wherein said precompensator is a Bragg-fiber grating.

8. The system of claim 1, wherein said optical fiber is a single mode fiber.

9. The system of claim 1, wherein said optical receiving means is a photoconductive element.

10. The system of claim 1, wherein said optical receiving means is an element that exhibits optical rectification.

11. The system of claim 1, wherein said antenna is a dipole antenna.

12. An optical distortion compensation apparatus comprising:

an optical fiber for transmitting an optical pulse, wherein the optical fiber positively disperses the optical pulse;

a precompensator in communication with the optical fiber for adding negative dispersion to the optical pulse to substantially eliminate the positive dispersion introduced by the optical fiber;

an optical switching means in communication with the precompensator and actuated by the optical pulse; and

an electrical circuit coupled to the optical switching means for generating a terahertz electromagnetic radiation.

13. The optical distortion compensation apparatus of claim 12 further comprising a terahertz receiver for detecting the terahertz electromagnetic radiation transmitted by the electrical circuit.

14. The optical distortion compensation apparatus of claim 12, wherein said precompensator is a prism pair.

15. The optical distortion compensation apparatus of claim 12, wherein said precompensator is a grism pair.

16. The optical distortion compensation apparatus of claim 12, wherein said precompensator is a three bounce arrangement.

17. The optical distortion compensation apparatus of claim 12, wherein said precompensator is a Treacy grating pair.

18. The optical distortion compensation apparatus of claim 12, wherein said precompensator is a Bragg-fiber grating.

19. The optical distortion compensation of claim 12, wherein said optical fiber is a single mode fiber.

20. The optical distortion compensation of claim 12, wherein said optical switching means is a photoconductive element.

21. The optical distortion compensation apparatus of claim 12, wherein said optical switching means is an element that exhibits the inverse electro-optic or Franz-Keldysh effect.

22. An optical system comprising:

an optical fiber for transmitting an optical pulse, wherein the optical pulse has a plurality of original dimensions; and

a grism pair coupled to the optical fiber for introducing dispersion of the optical pulse to compensate for dispersion caused by the optical fiber to substantially restore the optical pulse to the plurality of original dimensions; and

an optical transmitter for detecting the optical pulse and generating terahertz electromagnetic radiation.

23. A method for compensating for distortion in an optical pulse caused by transmitting the optical pulse through an optical medium, the method comprising:

identifying an amount of dispersion created in the optical pulse by the optical medium;

transmitting the optical pulse through the optical medium;

introducing a sufficient amount of dispersion into the optical pulse to eliminate the dispersion caused by the optical medium to create a restored optical pulse;

receiving the restored optical pulse; and

transmitting a terahertz electromagnetic radiation signal using an electric circuit excited by the restored optical pulse.