Method for Coupling Terahertz Pulses Into a Coaxial Waveguide

• US 20080309577A1
• Filed: 07/13/2005
• Published: 12/18/2008
• Est. Priority Date: 07/14/2004
• Status: Active Grant

• Current Assignee: Rice University
• Original Assignee: Rice University
• Inventors: Mittleman, Daniel M., Wang, Kanglin
• Granted Patent: US 9,178,282 B2
• Time in Patent Office: Days
• US Class Current: 343/850
• CPC Class Codes: G01N 21/3581 using far infrared light; using Terahertz radiation
• CPC Class Codes: H01P 5/02 with invariable factor of coupling H01P5/12 takes precedence choke joints H01P1/04, H01P1/06
• CPC Class Codes: H01Q 13/08 Radiating ends of two-conductor microwave transmission lines, e.g. of coaxial lines, of microstrip lines

Abstract

A system for coupling teraherz (THz) radiation to a coaxial waveguide comprises an antenna that generates THz radiation having a mode that matches the mode of the waveguide. The antenna may comprise a pair of concentric electrodes, at least one of which may be affixed to or formed by one end of the waveguide. The radiation may have wavelengths between approximately 30 μm and 3 mm. The waveguide may comprise an inner core and an outer wall defining an annular region. A terahertz sensor system may comprise a terahertz antenna comprising first and second concentric electrodes, means for generating a field across the trodes and means for triggering the emission of terahertz radiation, a first waveguide having first and second ends, said first end being coupled to said antenna so as to receive at least a portion of said terahertz radiation, and a sensor for detecting said terahertz radiation.

Claims

1. A system for coupling teraherz (THz) radiation to a coaxial waveguide, comprising:

an antenna that generates THz radiation having a mode that matches the mode of the waveguide, said antenna being positioned such that radiation emitted by said antenna is incident upon the waveguide.

2. The system according to claim 1 wherein the antenna comprises a pair of concentric electrodes.

3. The system according to claim 2 wherein at least one of the electrodes is affixed to one end of the waveguide.

4. The system according to claim 2 wherein at least one of said electrodes is formed by an end of the waveguide.

5. The system according to claim 1 wherein the waveguide includes an annular conducting region.

6. The system according to claim 1 wherein the waveguide includes an annular conducting region and the antenna emits radially polarized radiation.

7. A system for transmitting teraherz (THz) radiation, comprising:

an antenna comprising first and second electrodes, said first and second electrodes being substantially concentric and capable of emitting THz radiation in response to an application of energy;

a waveguide coupled to said antenna.

8. The system according to claim 7 wherein said antenna is affixed to one end of said waveguide.

9. The system according to claim 7, further including a second antenna affixed to a second end of said waveguide.

10. The system according to claim 7 wherein said waveguide comprises an inner core and an outer wall, said inner core and said outer wall being concentric and defining therebetween an annular region.

11. The system according to claim 10 wherein said annular region is filled with a gas.

12. The system according to claim 10 wherein said annular region is substantially evacuated.

13. The system according to claim 10, further including at least one support member in said annular region supporting said core relative to said outer wall.

14. The system according to claim 13 wherein said support member includes at least one fluid flow passage therethrough.

15. The system according to claim 10 wherein said outer wall includes at least one fluid flow passage therethrough.

16. The system according to claim 10 wherein said core is between 10⁻

4 and 3×

10<sup>−

2</sup> meters in diameter.

17. The system according to claim 10 wherein said core is between 10⁻

4 and 2×

10<sup>−

2</sup> meters in diameter.

18. The system according to claim 10 wherein said core is between 5×

10<sup>−

4</sup> and 10<sup>−

2</sup> meters in diameter.

19. The imaging system of claim 7 wherein said waveguide is at least 10 cm. in length.

20. The imaging system of claim 7 wherein said waveguide is at least 1 m. in length.

21. The imaging system of claim 7 wherein said waveguide is at least 10 m. in length.

22. A terahertz system, comprising:

a terahertz antenna comprising first and second electrodes, said first and second electrodes being substantially concentric;

means for generating a field across said electrodes and means for triggering the emission of terahertz radiation;

a first waveguide having first and second ends, said first end being coupled to said antenna so as to receive at least a portion of said terahertz radiation; and

a sensor for detecting said terahertz radiation.

23. The terahertz system of claim 22 wherein said sensor comprises a second terahertz antenna.

24. The terahertz system of claim 22, further comprising a second waveguide positioned to receive radiation from said second end of said first waveguide.

25. The terahertz system of claim 24 wherein said second waveguide is a uniaxial waveguide.

26. The terahertz system of claim 24, further including a reflector.

27. The terahertz system of claim 22 wherein said first waveguide is a uniaxial waveguide.

28. The terahertz system of claim 27 wherein said first waveguide includes at least one variation in diameter.

29. The terahertz system of claim 22 wherein said waveguide is at least 10 cm. in length.

30. The terahertz system of claim 22 wherein said waveguide is at least 1 m in length.

31. The terahertz system of claim 22 wherein said terahertz radiation has a frequency between about 0.1 and 50 THz.

32. A method for transmitting a signal, comprising:

generating a radially polarized signal having wavelengths between approximately 30 μ

m and 3 mm;

providing a waveguide having a mode that matches the mode of said beam; and

coupling said beam to said waveguide such that a portion of the energy of said beam is transmitted along said waveguide.

33. The method according to claim 32 wherein said radially polarized signal has wavelengths between approximately 50 μ

m and 800 μ

m.

34. The method according to claim 32 wherein said radially polarized signal has wavelengths between approximately 100 μ

m and 500 μ

m.

35. The method according to claim 32 wherein said portion comprises at least about 50% of the energy of said radially polarized signal.

36. The method according to claim 32 wherein said transmission is essentially dispersionless.

37. The method according to claim 32 wherein said transmission is results in a loss of energy from said coupled energy portion of less than 15% per meter.

38. The method according to claim 32 wherein said transmission is results in a loss of energy from said coupled energy portion of less than 10% per meter.

39. A terahertz near-field scanning optical microscope, comprising:

a terahertz transmitter;

a stage for receiving a sample;

a waveguide coupled to said transmitter, said waveguide including a tip in close proximity to said stage; and

a receiver positioned to receive terahertz radiation emitted from said tip and scattered by said sample.

40. The terahertz near-field scanning optical microscope of claim 39 wherein said waveguide is a wire waveguide.

41. The terahertz near-field scanning optical microscope of claim 39, further including an input coupler.

42. The terahertz near-field scanning optical microscope of claim 39 wherein said transmitter is a coaxial antenna.