Abstract

The stand-off imaging properties of a terahertz (THz) interferometric array are examined. For this application, the imaged object is in the near-field region limit of the imaging array. In this region, spherical and circular array architectures can compensate for near-field distortions and increase the field of view and depth of focus. Imaging of THz point sources is emphasized to demonstrate the imaging method and to compare theoretical predictions to experimental performance.

© 2006 Optical Society of America

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  1. D.L.Woolard, W.R.Loerop, and M.Shur, eds., Terahertz Sensing Technology, Vol. 2: Emerging Scientific Applications & Novel Device Concepts (World Scientific, 2003).
  2. D.Mittleman, ed., Sensing with Terahertz Radiation (Springer, 2003).
  3. See for example J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, "THz imaging and sensing for security applications—explosives, weapons, and drugs," Semicond. Sci. Technol. 20, S266-S280 (2005); http://stacks.iop.org/0268-1242/20/S266 and references therein.
    [CrossRef]
  4. B. B. Hu and M. C. Nuss, "Imaging with terahertz waves," Opt. Lett. 20, 1716-1718 (1995).
    [CrossRef] [PubMed]
  5. D. M. Mittleman, S. Hunsche, L. Boivin, and M. C. Nuss, "T-ray tomography," Opt. Lett. 22, 904-906 (1997).
    [CrossRef] [PubMed]
  6. D. A. Zimdars, "Fiber-pigtailed terahertz time-domain spectroscopy instrumentation for package inspection and security imaging," in Proc. SPIE 5070, 108-116 (2003).
    [CrossRef]
  7. W. R. Tribe, D. A. Newnham, P. F. Taday, and M. C. Kemp, "Hidden object detection: security applications of terahertz technology," in Proc. SPIE 5354, 168-176 (2004).
    [CrossRef]
  8. M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, "Security applications of terahertz technology," in Proc. SPIE 5070, 44-52 (2003).
    [CrossRef]
  9. D. Zimdars and J. S. White, "Terahertz reflection imaging for package and personnel inspection," in Proc. SPIE 5411, 78-83 (2004).
    [CrossRef]
  10. C. A. Schuetz and D. W. Prather, "Optical upconversion techniques for high-sensitivity millimeter-wave detection," in Proc. SPIE 5619, 166-174 (2004).
    [CrossRef]
  11. Q. Wu, T. D. Hewitt, and X. C. Zhang, "Two-dimensional electro-optic imaging of THz beams," Appl. Phys. Lett. 69, 1026-1028 (1996).
    [CrossRef]
  12. Z. Jiang and X. C. Zhang, "Single-shot spatiotemporal terahertz field imaging," Opt. Lett. 23, 1114-1116 (1998).
    [CrossRef]
  13. A. R. Thompson, J. M. Moran, and G. W. Swenson,Interferometry and Synthesis in Radio Astronomy, 2nd ed. (Wiley, 2001), p. 50.
    [CrossRef]
  14. K. McKlatchy, M. T. Reiten, and R. A. Cheville, "Time resolved synthetic aperture terahertz impulse imaging," Appl. Phys. Lett. 79, 4485-4487 (2001).
    [CrossRef]
  15. A. B. Ruffin, J. Decker, L. Sanchez-Palencia, L. Le Hors, J. F. Whitaker, T. B. Norris, and J. V. Rudd, "Time reversal and object reconstruction with single-cycle pulses," Opt. Lett. 26, 681-683 (2001).
    [CrossRef]
  16. T. D. Dorney, J. L. Johnson, J. Van Rudd, R. G. Baraniuk, W. W. Symes, and D. M. Mittleman, "Terahertz reflection imaging using Kirchhoff migration," Opt. Lett. 26, 1513-1515 (2001).
    [CrossRef]
  17. J. O'Hara and D. Grischkowsky, "Quasi-optic terahertz imaging," Opt. Lett. 26, 1918-1920 (2001).
    [CrossRef]
  18. J. O'Hara and D. Grischkowsky, "Synthetic phased-array terahertz imaging," Opt. Lett. 27, 1070-1072 (2002).
    [CrossRef]
  19. J. O'Hara and D. Grischkowsky, "Quasi-optic synthetic phased-array terahertz imaging," J. Opt. Soc. Am. B 21, 1178-1191 (2004).
    [CrossRef]
  20. D. H. Johnson and D. E. Dungeon, Array Signal Processing (Prentice Hall, 1993), pp. 114-115.
  21. J. F. Federici, D. Gary, B. Schulkin, F. Huang, H. Altan, R. Barat, and D. Zimdars, "Terahertz imaging using an interferometric array," Appl. Phys. Lett. 83, 2477-2479 (2003).
    [CrossRef]
  22. K. P. Walsh, B. Schulkin, D. Gary, J. F. Federici, R. Barat, and D. Zimdars, "Terahertz near-field interferometric and synthetic aperture imaging," in Proc. SPIE 5411, 9-17 (2004).
    [CrossRef]
  23. M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge U. Press, 1999), pp. 574-579.
  24. K. A. McIntosh, E. R. Brown, K. B. Nichols, O. B. McMahon, W. F. DiNatale, and T. M. Lyszczarz, "Terahertz photomixing with diode lasers in low-temperature-grown GaAs," Appl. Phys. Lett. 67, 3844-3846 (1995).
    [CrossRef]
  25. S. M. Duffy, S. Verghese, and K. A. McIntosh,"Photomixers for continuous-wave terahertz radiation," in Sensing with Terahertz Radiation, D.Mittleman, ed. (Springer, 2002).
  26. T. L. J. Chan, J. E. Bjarnason, A. W. M. Lee, M. A. Celis, and E. R. Brown, "Attenuation contract between biomolecular and inorganic materials at terahertz frequencies," Appl. Phys. Lett. 85, 2523-2525 (2004).
    [CrossRef]
  27. E. R. Brown, "Fundamentals of terrestrial millimeter-wave and THz remote sensing," in Ref. , pp. 93-96.
  28. T. Loffler, K. J. Siebert, H. Quast, N. Hasegawa, G. Lota, R. Wipe, T. Hahn, M. Thomson, R. Leonhardt, and H. G. Roskos, "All-optoelectronic continuous-wave terahertz systems," Philos. Trans. R. Soc. London, Ser. A 362, 263-265 (2004).
    [CrossRef]
  29. K. J. Siebert, T. Loffler, H. Quast, M. Thomason, T. Bauer, R. Leonhardt, S. Czasch, and H. G. Roskos, "All optoelectronic continuous wave THz imaging for biomedical applications," Phys. Med. Biol. 47, 2743-2750 (2002).
    [CrossRef]
  30. K. J. Siebert, H. Quast, R. Leonhardt, T. Loffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, "Continuous-wave all-optoelectronic terahertz imaging," Appl. Phys. Lett. 80, 3003-3005 (2002).
    [CrossRef]
  31. T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffman, M. Breede, M. Hofmann, G. Hain, K. Pierz, M. Sperling, and K. Donhuijsen, "Continuous-wave THz imaging," Electron. Lett. 37, 1461-1463 (2001).
    [CrossRef]
  32. I. S. Gregory, W. R. Tribe, B. E. Cole, C. Baker, M. J. Evans, I. V. Bradley, E. H. Linfiled, A. G. Davies, and M. Missous, "Phase sensitive continuous-wave THz imaging using diode lasers," Electron. Lett. 40, 143-145 (2004).
    [CrossRef]
  33. J. E. Bjarnason, T. L. J. Chan, A. W. M. Lee, E. R. Brown, D. C. Driscoll, M. Hanson, A. C. Gassard, and R. E. Muller, "ErAs:GaAs photomixer with two-decade tunability and 12 μW peak output power," Appl. Phys. Lett. 85, 3983-3985 (2004).
    [CrossRef]
  34. S. Verghese, K. A. McIntosh, and E. R. Brown, "Optical and terahertz power limits in the low-temperature-grown GaAs photomixers," Appl. Phys. Lett. 71, 2743-2745(1997).
    [CrossRef]
  35. V. Ryzhii, I. Khmyrova, and M. Shur, "Terahertz photomixing in quantum well structures using resonant excitation of plasma oscillations," J. Appl. Phys. 91, 1875-1881 (2002).
    [CrossRef]
  36. V. Ryzhii, I. Khmyrova, A. Satou, P. O. Vaccaro, T. Aida, and M. Shur, "Plasma mechanism of terahertz photomixing in high-electron mobility transistor under interband photoexcitation," J. Appl. Phys. 92, 5756-5760 (2002).
    [CrossRef]
  37. A. Malcoci, A. Stohr, A. Sauerwald, S. Schulz, and D. Jager, "Waveguide and antenna coupled traveling-wave 1.55 μm photodetectors for optical (sub)millimeter-wave generation," in Proc. SPIE 5466, 202-209 (2004).
    [CrossRef]
  38. A. Nahata, J. T. Yardley, and T. F. Heinz, "Two-dimensional imaging of continuous-wave terahertz radiation using electro-optic detection," Appl. Phys. Lett. 81, 963-965 (2002).
    [CrossRef]
  39. J. Van Rudd and D. Mittleman, "Influence of substrate-lens design in terahertz time-domain spectroscopy," J. Opt. Soc. Am. B 19, 319-329 (2002).
    [CrossRef]
  40. M. Tani, P. Gu, M. Hyodo, K. Saki, and T. Hidaka, "Generation of coherent terahertz radiation by photomixing of dual-mode lasers," Opt. Quantum Electron. 32, 503-520 (2000).
    [CrossRef]

2005 (1)

See for example J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, "THz imaging and sensing for security applications—explosives, weapons, and drugs," Semicond. Sci. Technol. 20, S266-S280 (2005); http://stacks.iop.org/0268-1242/20/S266 and references therein.
[CrossRef]

2004 (10)

W. R. Tribe, D. A. Newnham, P. F. Taday, and M. C. Kemp, "Hidden object detection: security applications of terahertz technology," in Proc. SPIE 5354, 168-176 (2004).
[CrossRef]

D. Zimdars and J. S. White, "Terahertz reflection imaging for package and personnel inspection," in Proc. SPIE 5411, 78-83 (2004).
[CrossRef]

C. A. Schuetz and D. W. Prather, "Optical upconversion techniques for high-sensitivity millimeter-wave detection," in Proc. SPIE 5619, 166-174 (2004).
[CrossRef]

J. O'Hara and D. Grischkowsky, "Quasi-optic synthetic phased-array terahertz imaging," J. Opt. Soc. Am. B 21, 1178-1191 (2004).
[CrossRef]

K. P. Walsh, B. Schulkin, D. Gary, J. F. Federici, R. Barat, and D. Zimdars, "Terahertz near-field interferometric and synthetic aperture imaging," in Proc. SPIE 5411, 9-17 (2004).
[CrossRef]

T. L. J. Chan, J. E. Bjarnason, A. W. M. Lee, M. A. Celis, and E. R. Brown, "Attenuation contract between biomolecular and inorganic materials at terahertz frequencies," Appl. Phys. Lett. 85, 2523-2525 (2004).
[CrossRef]

T. Loffler, K. J. Siebert, H. Quast, N. Hasegawa, G. Lota, R. Wipe, T. Hahn, M. Thomson, R. Leonhardt, and H. G. Roskos, "All-optoelectronic continuous-wave terahertz systems," Philos. Trans. R. Soc. London, Ser. A 362, 263-265 (2004).
[CrossRef]

I. S. Gregory, W. R. Tribe, B. E. Cole, C. Baker, M. J. Evans, I. V. Bradley, E. H. Linfiled, A. G. Davies, and M. Missous, "Phase sensitive continuous-wave THz imaging using diode lasers," Electron. Lett. 40, 143-145 (2004).
[CrossRef]

J. E. Bjarnason, T. L. J. Chan, A. W. M. Lee, E. R. Brown, D. C. Driscoll, M. Hanson, A. C. Gassard, and R. E. Muller, "ErAs:GaAs photomixer with two-decade tunability and 12 μW peak output power," Appl. Phys. Lett. 85, 3983-3985 (2004).
[CrossRef]

A. Malcoci, A. Stohr, A. Sauerwald, S. Schulz, and D. Jager, "Waveguide and antenna coupled traveling-wave 1.55 μm photodetectors for optical (sub)millimeter-wave generation," in Proc. SPIE 5466, 202-209 (2004).
[CrossRef]

2003 (5)

J. F. Federici, D. Gary, B. Schulkin, F. Huang, H. Altan, R. Barat, and D. Zimdars, "Terahertz imaging using an interferometric array," Appl. Phys. Lett. 83, 2477-2479 (2003).
[CrossRef]

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, "Security applications of terahertz technology," in Proc. SPIE 5070, 44-52 (2003).
[CrossRef]

D. A. Zimdars, "Fiber-pigtailed terahertz time-domain spectroscopy instrumentation for package inspection and security imaging," in Proc. SPIE 5070, 108-116 (2003).
[CrossRef]

D.L.Woolard, W.R.Loerop, and M.Shur, eds., Terahertz Sensing Technology, Vol. 2: Emerging Scientific Applications & Novel Device Concepts (World Scientific, 2003).

D.Mittleman, ed., Sensing with Terahertz Radiation (Springer, 2003).

2002 (8)

J. O'Hara and D. Grischkowsky, "Synthetic phased-array terahertz imaging," Opt. Lett. 27, 1070-1072 (2002).
[CrossRef]

S. M. Duffy, S. Verghese, and K. A. McIntosh,"Photomixers for continuous-wave terahertz radiation," in Sensing with Terahertz Radiation, D.Mittleman, ed. (Springer, 2002).

A. Nahata, J. T. Yardley, and T. F. Heinz, "Two-dimensional imaging of continuous-wave terahertz radiation using electro-optic detection," Appl. Phys. Lett. 81, 963-965 (2002).
[CrossRef]

J. Van Rudd and D. Mittleman, "Influence of substrate-lens design in terahertz time-domain spectroscopy," J. Opt. Soc. Am. B 19, 319-329 (2002).
[CrossRef]

K. J. Siebert, T. Loffler, H. Quast, M. Thomason, T. Bauer, R. Leonhardt, S. Czasch, and H. G. Roskos, "All optoelectronic continuous wave THz imaging for biomedical applications," Phys. Med. Biol. 47, 2743-2750 (2002).
[CrossRef]

K. J. Siebert, H. Quast, R. Leonhardt, T. Loffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, "Continuous-wave all-optoelectronic terahertz imaging," Appl. Phys. Lett. 80, 3003-3005 (2002).
[CrossRef]

V. Ryzhii, I. Khmyrova, and M. Shur, "Terahertz photomixing in quantum well structures using resonant excitation of plasma oscillations," J. Appl. Phys. 91, 1875-1881 (2002).
[CrossRef]

V. Ryzhii, I. Khmyrova, A. Satou, P. O. Vaccaro, T. Aida, and M. Shur, "Plasma mechanism of terahertz photomixing in high-electron mobility transistor under interband photoexcitation," J. Appl. Phys. 92, 5756-5760 (2002).
[CrossRef]

2001 (6)

T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffman, M. Breede, M. Hofmann, G. Hain, K. Pierz, M. Sperling, and K. Donhuijsen, "Continuous-wave THz imaging," Electron. Lett. 37, 1461-1463 (2001).
[CrossRef]

A. R. Thompson, J. M. Moran, and G. W. Swenson,Interferometry and Synthesis in Radio Astronomy, 2nd ed. (Wiley, 2001), p. 50.
[CrossRef]

K. McKlatchy, M. T. Reiten, and R. A. Cheville, "Time resolved synthetic aperture terahertz impulse imaging," Appl. Phys. Lett. 79, 4485-4487 (2001).
[CrossRef]

A. B. Ruffin, J. Decker, L. Sanchez-Palencia, L. Le Hors, J. F. Whitaker, T. B. Norris, and J. V. Rudd, "Time reversal and object reconstruction with single-cycle pulses," Opt. Lett. 26, 681-683 (2001).
[CrossRef]

T. D. Dorney, J. L. Johnson, J. Van Rudd, R. G. Baraniuk, W. W. Symes, and D. M. Mittleman, "Terahertz reflection imaging using Kirchhoff migration," Opt. Lett. 26, 1513-1515 (2001).
[CrossRef]

J. O'Hara and D. Grischkowsky, "Quasi-optic terahertz imaging," Opt. Lett. 26, 1918-1920 (2001).
[CrossRef]

2000 (1)

M. Tani, P. Gu, M. Hyodo, K. Saki, and T. Hidaka, "Generation of coherent terahertz radiation by photomixing of dual-mode lasers," Opt. Quantum Electron. 32, 503-520 (2000).
[CrossRef]

1999 (1)

M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge U. Press, 1999), pp. 574-579.

1998 (1)

1997 (2)

D. M. Mittleman, S. Hunsche, L. Boivin, and M. C. Nuss, "T-ray tomography," Opt. Lett. 22, 904-906 (1997).
[CrossRef] [PubMed]

S. Verghese, K. A. McIntosh, and E. R. Brown, "Optical and terahertz power limits in the low-temperature-grown GaAs photomixers," Appl. Phys. Lett. 71, 2743-2745(1997).
[CrossRef]

1996 (1)

Q. Wu, T. D. Hewitt, and X. C. Zhang, "Two-dimensional electro-optic imaging of THz beams," Appl. Phys. Lett. 69, 1026-1028 (1996).
[CrossRef]

1995 (2)

B. B. Hu and M. C. Nuss, "Imaging with terahertz waves," Opt. Lett. 20, 1716-1718 (1995).
[CrossRef] [PubMed]

K. A. McIntosh, E. R. Brown, K. B. Nichols, O. B. McMahon, W. F. DiNatale, and T. M. Lyszczarz, "Terahertz photomixing with diode lasers in low-temperature-grown GaAs," Appl. Phys. Lett. 67, 3844-3846 (1995).
[CrossRef]

1993 (1)

D. H. Johnson and D. E. Dungeon, Array Signal Processing (Prentice Hall, 1993), pp. 114-115.

Aida, T.

V. Ryzhii, I. Khmyrova, A. Satou, P. O. Vaccaro, T. Aida, and M. Shur, "Plasma mechanism of terahertz photomixing in high-electron mobility transistor under interband photoexcitation," J. Appl. Phys. 92, 5756-5760 (2002).
[CrossRef]

Altan, H.

J. F. Federici, D. Gary, B. Schulkin, F. Huang, H. Altan, R. Barat, and D. Zimdars, "Terahertz imaging using an interferometric array," Appl. Phys. Lett. 83, 2477-2479 (2003).
[CrossRef]

Baker, C.

I. S. Gregory, W. R. Tribe, B. E. Cole, C. Baker, M. J. Evans, I. V. Bradley, E. H. Linfiled, A. G. Davies, and M. Missous, "Phase sensitive continuous-wave THz imaging using diode lasers," Electron. Lett. 40, 143-145 (2004).
[CrossRef]

Baraniuk, R. G.

Barat, R.

See for example J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, "THz imaging and sensing for security applications—explosives, weapons, and drugs," Semicond. Sci. Technol. 20, S266-S280 (2005); http://stacks.iop.org/0268-1242/20/S266 and references therein.
[CrossRef]

K. P. Walsh, B. Schulkin, D. Gary, J. F. Federici, R. Barat, and D. Zimdars, "Terahertz near-field interferometric and synthetic aperture imaging," in Proc. SPIE 5411, 9-17 (2004).
[CrossRef]

J. F. Federici, D. Gary, B. Schulkin, F. Huang, H. Altan, R. Barat, and D. Zimdars, "Terahertz imaging using an interferometric array," Appl. Phys. Lett. 83, 2477-2479 (2003).
[CrossRef]

Bauer, T.

K. J. Siebert, T. Loffler, H. Quast, M. Thomason, T. Bauer, R. Leonhardt, S. Czasch, and H. G. Roskos, "All optoelectronic continuous wave THz imaging for biomedical applications," Phys. Med. Biol. 47, 2743-2750 (2002).
[CrossRef]

K. J. Siebert, H. Quast, R. Leonhardt, T. Loffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, "Continuous-wave all-optoelectronic terahertz imaging," Appl. Phys. Lett. 80, 3003-3005 (2002).
[CrossRef]

Bjarnason, J. E.

J. E. Bjarnason, T. L. J. Chan, A. W. M. Lee, E. R. Brown, D. C. Driscoll, M. Hanson, A. C. Gassard, and R. E. Muller, "ErAs:GaAs photomixer with two-decade tunability and 12 μW peak output power," Appl. Phys. Lett. 85, 3983-3985 (2004).
[CrossRef]

T. L. J. Chan, J. E. Bjarnason, A. W. M. Lee, M. A. Celis, and E. R. Brown, "Attenuation contract between biomolecular and inorganic materials at terahertz frequencies," Appl. Phys. Lett. 85, 2523-2525 (2004).
[CrossRef]

Boivin, L.

Born, M.

M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge U. Press, 1999), pp. 574-579.

Bradley, I. V.

I. S. Gregory, W. R. Tribe, B. E. Cole, C. Baker, M. J. Evans, I. V. Bradley, E. H. Linfiled, A. G. Davies, and M. Missous, "Phase sensitive continuous-wave THz imaging using diode lasers," Electron. Lett. 40, 143-145 (2004).
[CrossRef]

Breede, M.

T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffman, M. Breede, M. Hofmann, G. Hain, K. Pierz, M. Sperling, and K. Donhuijsen, "Continuous-wave THz imaging," Electron. Lett. 37, 1461-1463 (2001).
[CrossRef]

Brown, E. R.

J. E. Bjarnason, T. L. J. Chan, A. W. M. Lee, E. R. Brown, D. C. Driscoll, M. Hanson, A. C. Gassard, and R. E. Muller, "ErAs:GaAs photomixer with two-decade tunability and 12 μW peak output power," Appl. Phys. Lett. 85, 3983-3985 (2004).
[CrossRef]

T. L. J. Chan, J. E. Bjarnason, A. W. M. Lee, M. A. Celis, and E. R. Brown, "Attenuation contract between biomolecular and inorganic materials at terahertz frequencies," Appl. Phys. Lett. 85, 2523-2525 (2004).
[CrossRef]

S. Verghese, K. A. McIntosh, and E. R. Brown, "Optical and terahertz power limits in the low-temperature-grown GaAs photomixers," Appl. Phys. Lett. 71, 2743-2745(1997).
[CrossRef]

K. A. McIntosh, E. R. Brown, K. B. Nichols, O. B. McMahon, W. F. DiNatale, and T. M. Lyszczarz, "Terahertz photomixing with diode lasers in low-temperature-grown GaAs," Appl. Phys. Lett. 67, 3844-3846 (1995).
[CrossRef]

E. R. Brown, "Fundamentals of terrestrial millimeter-wave and THz remote sensing," in Ref. , pp. 93-96.

Celis, M. A.

T. L. J. Chan, J. E. Bjarnason, A. W. M. Lee, M. A. Celis, and E. R. Brown, "Attenuation contract between biomolecular and inorganic materials at terahertz frequencies," Appl. Phys. Lett. 85, 2523-2525 (2004).
[CrossRef]

Chan, T. L. J.

T. L. J. Chan, J. E. Bjarnason, A. W. M. Lee, M. A. Celis, and E. R. Brown, "Attenuation contract between biomolecular and inorganic materials at terahertz frequencies," Appl. Phys. Lett. 85, 2523-2525 (2004).
[CrossRef]

J. E. Bjarnason, T. L. J. Chan, A. W. M. Lee, E. R. Brown, D. C. Driscoll, M. Hanson, A. C. Gassard, and R. E. Muller, "ErAs:GaAs photomixer with two-decade tunability and 12 μW peak output power," Appl. Phys. Lett. 85, 3983-3985 (2004).
[CrossRef]

Cheville, R. A.

K. McKlatchy, M. T. Reiten, and R. A. Cheville, "Time resolved synthetic aperture terahertz impulse imaging," Appl. Phys. Lett. 79, 4485-4487 (2001).
[CrossRef]

Cluff, J. A.

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, "Security applications of terahertz technology," in Proc. SPIE 5070, 44-52 (2003).
[CrossRef]

Cole, B. E.

I. S. Gregory, W. R. Tribe, B. E. Cole, C. Baker, M. J. Evans, I. V. Bradley, E. H. Linfiled, A. G. Davies, and M. Missous, "Phase sensitive continuous-wave THz imaging using diode lasers," Electron. Lett. 40, 143-145 (2004).
[CrossRef]

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, "Security applications of terahertz technology," in Proc. SPIE 5070, 44-52 (2003).
[CrossRef]

Czasch, S.

K. J. Siebert, H. Quast, R. Leonhardt, T. Loffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, "Continuous-wave all-optoelectronic terahertz imaging," Appl. Phys. Lett. 80, 3003-3005 (2002).
[CrossRef]

K. J. Siebert, T. Loffler, H. Quast, M. Thomason, T. Bauer, R. Leonhardt, S. Czasch, and H. G. Roskos, "All optoelectronic continuous wave THz imaging for biomedical applications," Phys. Med. Biol. 47, 2743-2750 (2002).
[CrossRef]

Davies, A. G.

I. S. Gregory, W. R. Tribe, B. E. Cole, C. Baker, M. J. Evans, I. V. Bradley, E. H. Linfiled, A. G. Davies, and M. Missous, "Phase sensitive continuous-wave THz imaging using diode lasers," Electron. Lett. 40, 143-145 (2004).
[CrossRef]

Decker, J.

DiNatale, W. F.

K. A. McIntosh, E. R. Brown, K. B. Nichols, O. B. McMahon, W. F. DiNatale, and T. M. Lyszczarz, "Terahertz photomixing with diode lasers in low-temperature-grown GaAs," Appl. Phys. Lett. 67, 3844-3846 (1995).
[CrossRef]

Donhuijsen, K.

T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffman, M. Breede, M. Hofmann, G. Hain, K. Pierz, M. Sperling, and K. Donhuijsen, "Continuous-wave THz imaging," Electron. Lett. 37, 1461-1463 (2001).
[CrossRef]

Dorney, T. D.

Driscoll, D. C.

J. E. Bjarnason, T. L. J. Chan, A. W. M. Lee, E. R. Brown, D. C. Driscoll, M. Hanson, A. C. Gassard, and R. E. Muller, "ErAs:GaAs photomixer with two-decade tunability and 12 μW peak output power," Appl. Phys. Lett. 85, 3983-3985 (2004).
[CrossRef]

Duffy, S. M.

S. M. Duffy, S. Verghese, and K. A. McIntosh,"Photomixers for continuous-wave terahertz radiation," in Sensing with Terahertz Radiation, D.Mittleman, ed. (Springer, 2002).

Dungeon, D. E.

D. H. Johnson and D. E. Dungeon, Array Signal Processing (Prentice Hall, 1993), pp. 114-115.

Evans, M. J.

I. S. Gregory, W. R. Tribe, B. E. Cole, C. Baker, M. J. Evans, I. V. Bradley, E. H. Linfiled, A. G. Davies, and M. Missous, "Phase sensitive continuous-wave THz imaging using diode lasers," Electron. Lett. 40, 143-145 (2004).
[CrossRef]

Federici, J. F.

See for example J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, "THz imaging and sensing for security applications—explosives, weapons, and drugs," Semicond. Sci. Technol. 20, S266-S280 (2005); http://stacks.iop.org/0268-1242/20/S266 and references therein.
[CrossRef]

K. P. Walsh, B. Schulkin, D. Gary, J. F. Federici, R. Barat, and D. Zimdars, "Terahertz near-field interferometric and synthetic aperture imaging," in Proc. SPIE 5411, 9-17 (2004).
[CrossRef]

J. F. Federici, D. Gary, B. Schulkin, F. Huang, H. Altan, R. Barat, and D. Zimdars, "Terahertz imaging using an interferometric array," Appl. Phys. Lett. 83, 2477-2479 (2003).
[CrossRef]

Fitzgerald, A. J.

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, "Security applications of terahertz technology," in Proc. SPIE 5070, 44-52 (2003).
[CrossRef]

Gary, D.

See for example J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, "THz imaging and sensing for security applications—explosives, weapons, and drugs," Semicond. Sci. Technol. 20, S266-S280 (2005); http://stacks.iop.org/0268-1242/20/S266 and references therein.
[CrossRef]

K. P. Walsh, B. Schulkin, D. Gary, J. F. Federici, R. Barat, and D. Zimdars, "Terahertz near-field interferometric and synthetic aperture imaging," in Proc. SPIE 5411, 9-17 (2004).
[CrossRef]

J. F. Federici, D. Gary, B. Schulkin, F. Huang, H. Altan, R. Barat, and D. Zimdars, "Terahertz imaging using an interferometric array," Appl. Phys. Lett. 83, 2477-2479 (2003).
[CrossRef]

Gassard, A. C.

J. E. Bjarnason, T. L. J. Chan, A. W. M. Lee, E. R. Brown, D. C. Driscoll, M. Hanson, A. C. Gassard, and R. E. Muller, "ErAs:GaAs photomixer with two-decade tunability and 12 μW peak output power," Appl. Phys. Lett. 85, 3983-3985 (2004).
[CrossRef]

Gregory, I. S.

I. S. Gregory, W. R. Tribe, B. E. Cole, C. Baker, M. J. Evans, I. V. Bradley, E. H. Linfiled, A. G. Davies, and M. Missous, "Phase sensitive continuous-wave THz imaging using diode lasers," Electron. Lett. 40, 143-145 (2004).
[CrossRef]

Grischkowsky, D.

Gu, P.

M. Tani, P. Gu, M. Hyodo, K. Saki, and T. Hidaka, "Generation of coherent terahertz radiation by photomixing of dual-mode lasers," Opt. Quantum Electron. 32, 503-520 (2000).
[CrossRef]

Hahn, T.

T. Loffler, K. J. Siebert, H. Quast, N. Hasegawa, G. Lota, R. Wipe, T. Hahn, M. Thomson, R. Leonhardt, and H. G. Roskos, "All-optoelectronic continuous-wave terahertz systems," Philos. Trans. R. Soc. London, Ser. A 362, 263-265 (2004).
[CrossRef]

Hain, G.

T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffman, M. Breede, M. Hofmann, G. Hain, K. Pierz, M. Sperling, and K. Donhuijsen, "Continuous-wave THz imaging," Electron. Lett. 37, 1461-1463 (2001).
[CrossRef]

Hanson, M.

J. E. Bjarnason, T. L. J. Chan, A. W. M. Lee, E. R. Brown, D. C. Driscoll, M. Hanson, A. C. Gassard, and R. E. Muller, "ErAs:GaAs photomixer with two-decade tunability and 12 μW peak output power," Appl. Phys. Lett. 85, 3983-3985 (2004).
[CrossRef]

Hasegawa, N.

T. Loffler, K. J. Siebert, H. Quast, N. Hasegawa, G. Lota, R. Wipe, T. Hahn, M. Thomson, R. Leonhardt, and H. G. Roskos, "All-optoelectronic continuous-wave terahertz systems," Philos. Trans. R. Soc. London, Ser. A 362, 263-265 (2004).
[CrossRef]

Heinz, T. F.

A. Nahata, J. T. Yardley, and T. F. Heinz, "Two-dimensional imaging of continuous-wave terahertz radiation using electro-optic detection," Appl. Phys. Lett. 81, 963-965 (2002).
[CrossRef]

Hewitt, T. D.

Q. Wu, T. D. Hewitt, and X. C. Zhang, "Two-dimensional electro-optic imaging of THz beams," Appl. Phys. Lett. 69, 1026-1028 (1996).
[CrossRef]

Hidaka, T.

M. Tani, P. Gu, M. Hyodo, K. Saki, and T. Hidaka, "Generation of coherent terahertz radiation by photomixing of dual-mode lasers," Opt. Quantum Electron. 32, 503-520 (2000).
[CrossRef]

Hoffman, S.

T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffman, M. Breede, M. Hofmann, G. Hain, K. Pierz, M. Sperling, and K. Donhuijsen, "Continuous-wave THz imaging," Electron. Lett. 37, 1461-1463 (2001).
[CrossRef]

Hofmann, M.

T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffman, M. Breede, M. Hofmann, G. Hain, K. Pierz, M. Sperling, and K. Donhuijsen, "Continuous-wave THz imaging," Electron. Lett. 37, 1461-1463 (2001).
[CrossRef]

Hu, B. B.

Huang, F.

See for example J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, "THz imaging and sensing for security applications—explosives, weapons, and drugs," Semicond. Sci. Technol. 20, S266-S280 (2005); http://stacks.iop.org/0268-1242/20/S266 and references therein.
[CrossRef]

J. F. Federici, D. Gary, B. Schulkin, F. Huang, H. Altan, R. Barat, and D. Zimdars, "Terahertz imaging using an interferometric array," Appl. Phys. Lett. 83, 2477-2479 (2003).
[CrossRef]

Hunsche, S.

Hyodo, M.

M. Tani, P. Gu, M. Hyodo, K. Saki, and T. Hidaka, "Generation of coherent terahertz radiation by photomixing of dual-mode lasers," Opt. Quantum Electron. 32, 503-520 (2000).
[CrossRef]

Jager, D.

A. Malcoci, A. Stohr, A. Sauerwald, S. Schulz, and D. Jager, "Waveguide and antenna coupled traveling-wave 1.55 μm photodetectors for optical (sub)millimeter-wave generation," in Proc. SPIE 5466, 202-209 (2004).
[CrossRef]

Jiang, Z.

Johnson, D. H.

D. H. Johnson and D. E. Dungeon, Array Signal Processing (Prentice Hall, 1993), pp. 114-115.

Johnson, J. L.

Kemp, M. C.

W. R. Tribe, D. A. Newnham, P. F. Taday, and M. C. Kemp, "Hidden object detection: security applications of terahertz technology," in Proc. SPIE 5354, 168-176 (2004).
[CrossRef]

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, "Security applications of terahertz technology," in Proc. SPIE 5070, 44-52 (2003).
[CrossRef]

Khmyrova, I.

V. Ryzhii, I. Khmyrova, and M. Shur, "Terahertz photomixing in quantum well structures using resonant excitation of plasma oscillations," J. Appl. Phys. 91, 1875-1881 (2002).
[CrossRef]

V. Ryzhii, I. Khmyrova, A. Satou, P. O. Vaccaro, T. Aida, and M. Shur, "Plasma mechanism of terahertz photomixing in high-electron mobility transistor under interband photoexcitation," J. Appl. Phys. 92, 5756-5760 (2002).
[CrossRef]

Kleine-Ostmann, T.

T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffman, M. Breede, M. Hofmann, G. Hain, K. Pierz, M. Sperling, and K. Donhuijsen, "Continuous-wave THz imaging," Electron. Lett. 37, 1461-1463 (2001).
[CrossRef]

Knobloch, P.

T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffman, M. Breede, M. Hofmann, G. Hain, K. Pierz, M. Sperling, and K. Donhuijsen, "Continuous-wave THz imaging," Electron. Lett. 37, 1461-1463 (2001).
[CrossRef]

Koch, M.

T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffman, M. Breede, M. Hofmann, G. Hain, K. Pierz, M. Sperling, and K. Donhuijsen, "Continuous-wave THz imaging," Electron. Lett. 37, 1461-1463 (2001).
[CrossRef]

Le Hors, L.

Lee, A. W. M.

J. E. Bjarnason, T. L. J. Chan, A. W. M. Lee, E. R. Brown, D. C. Driscoll, M. Hanson, A. C. Gassard, and R. E. Muller, "ErAs:GaAs photomixer with two-decade tunability and 12 μW peak output power," Appl. Phys. Lett. 85, 3983-3985 (2004).
[CrossRef]

T. L. J. Chan, J. E. Bjarnason, A. W. M. Lee, M. A. Celis, and E. R. Brown, "Attenuation contract between biomolecular and inorganic materials at terahertz frequencies," Appl. Phys. Lett. 85, 2523-2525 (2004).
[CrossRef]

Leonhardt, R.

T. Loffler, K. J. Siebert, H. Quast, N. Hasegawa, G. Lota, R. Wipe, T. Hahn, M. Thomson, R. Leonhardt, and H. G. Roskos, "All-optoelectronic continuous-wave terahertz systems," Philos. Trans. R. Soc. London, Ser. A 362, 263-265 (2004).
[CrossRef]

K. J. Siebert, T. Loffler, H. Quast, M. Thomason, T. Bauer, R. Leonhardt, S. Czasch, and H. G. Roskos, "All optoelectronic continuous wave THz imaging for biomedical applications," Phys. Med. Biol. 47, 2743-2750 (2002).
[CrossRef]

K. J. Siebert, H. Quast, R. Leonhardt, T. Loffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, "Continuous-wave all-optoelectronic terahertz imaging," Appl. Phys. Lett. 80, 3003-3005 (2002).
[CrossRef]

Linfiled, E. H.

I. S. Gregory, W. R. Tribe, B. E. Cole, C. Baker, M. J. Evans, I. V. Bradley, E. H. Linfiled, A. G. Davies, and M. Missous, "Phase sensitive continuous-wave THz imaging using diode lasers," Electron. Lett. 40, 143-145 (2004).
[CrossRef]

Loffler, T.

T. Loffler, K. J. Siebert, H. Quast, N. Hasegawa, G. Lota, R. Wipe, T. Hahn, M. Thomson, R. Leonhardt, and H. G. Roskos, "All-optoelectronic continuous-wave terahertz systems," Philos. Trans. R. Soc. London, Ser. A 362, 263-265 (2004).
[CrossRef]

K. J. Siebert, T. Loffler, H. Quast, M. Thomason, T. Bauer, R. Leonhardt, S. Czasch, and H. G. Roskos, "All optoelectronic continuous wave THz imaging for biomedical applications," Phys. Med. Biol. 47, 2743-2750 (2002).
[CrossRef]

K. J. Siebert, H. Quast, R. Leonhardt, T. Loffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, "Continuous-wave all-optoelectronic terahertz imaging," Appl. Phys. Lett. 80, 3003-3005 (2002).
[CrossRef]

Lota, G.

T. Loffler, K. J. Siebert, H. Quast, N. Hasegawa, G. Lota, R. Wipe, T. Hahn, M. Thomson, R. Leonhardt, and H. G. Roskos, "All-optoelectronic continuous-wave terahertz systems," Philos. Trans. R. Soc. London, Ser. A 362, 263-265 (2004).
[CrossRef]

Lyszczarz, T. M.

K. A. McIntosh, E. R. Brown, K. B. Nichols, O. B. McMahon, W. F. DiNatale, and T. M. Lyszczarz, "Terahertz photomixing with diode lasers in low-temperature-grown GaAs," Appl. Phys. Lett. 67, 3844-3846 (1995).
[CrossRef]

Malcoci, A.

A. Malcoci, A. Stohr, A. Sauerwald, S. Schulz, and D. Jager, "Waveguide and antenna coupled traveling-wave 1.55 μm photodetectors for optical (sub)millimeter-wave generation," in Proc. SPIE 5466, 202-209 (2004).
[CrossRef]

McIntosh, K. A.

S. M. Duffy, S. Verghese, and K. A. McIntosh,"Photomixers for continuous-wave terahertz radiation," in Sensing with Terahertz Radiation, D.Mittleman, ed. (Springer, 2002).

S. Verghese, K. A. McIntosh, and E. R. Brown, "Optical and terahertz power limits in the low-temperature-grown GaAs photomixers," Appl. Phys. Lett. 71, 2743-2745(1997).
[CrossRef]

K. A. McIntosh, E. R. Brown, K. B. Nichols, O. B. McMahon, W. F. DiNatale, and T. M. Lyszczarz, "Terahertz photomixing with diode lasers in low-temperature-grown GaAs," Appl. Phys. Lett. 67, 3844-3846 (1995).
[CrossRef]

McKlatchy, K.

K. McKlatchy, M. T. Reiten, and R. A. Cheville, "Time resolved synthetic aperture terahertz impulse imaging," Appl. Phys. Lett. 79, 4485-4487 (2001).
[CrossRef]

McMahon, O. B.

K. A. McIntosh, E. R. Brown, K. B. Nichols, O. B. McMahon, W. F. DiNatale, and T. M. Lyszczarz, "Terahertz photomixing with diode lasers in low-temperature-grown GaAs," Appl. Phys. Lett. 67, 3844-3846 (1995).
[CrossRef]

Missous, M.

I. S. Gregory, W. R. Tribe, B. E. Cole, C. Baker, M. J. Evans, I. V. Bradley, E. H. Linfiled, A. G. Davies, and M. Missous, "Phase sensitive continuous-wave THz imaging using diode lasers," Electron. Lett. 40, 143-145 (2004).
[CrossRef]

Mittleman, D.

Mittleman, D. M.

Moran, J. M.

A. R. Thompson, J. M. Moran, and G. W. Swenson,Interferometry and Synthesis in Radio Astronomy, 2nd ed. (Wiley, 2001), p. 50.
[CrossRef]

Muller, R. E.

J. E. Bjarnason, T. L. J. Chan, A. W. M. Lee, E. R. Brown, D. C. Driscoll, M. Hanson, A. C. Gassard, and R. E. Muller, "ErAs:GaAs photomixer with two-decade tunability and 12 μW peak output power," Appl. Phys. Lett. 85, 3983-3985 (2004).
[CrossRef]

Nahata, A.

A. Nahata, J. T. Yardley, and T. F. Heinz, "Two-dimensional imaging of continuous-wave terahertz radiation using electro-optic detection," Appl. Phys. Lett. 81, 963-965 (2002).
[CrossRef]

Newnham, D. A.

W. R. Tribe, D. A. Newnham, P. F. Taday, and M. C. Kemp, "Hidden object detection: security applications of terahertz technology," in Proc. SPIE 5354, 168-176 (2004).
[CrossRef]

Nichols, K. B.

K. A. McIntosh, E. R. Brown, K. B. Nichols, O. B. McMahon, W. F. DiNatale, and T. M. Lyszczarz, "Terahertz photomixing with diode lasers in low-temperature-grown GaAs," Appl. Phys. Lett. 67, 3844-3846 (1995).
[CrossRef]

Norris, T. B.

Nuss, M. C.

O'Hara, J.

Oliveira, F.

See for example J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, "THz imaging and sensing for security applications—explosives, weapons, and drugs," Semicond. Sci. Technol. 20, S266-S280 (2005); http://stacks.iop.org/0268-1242/20/S266 and references therein.
[CrossRef]

Pierz, K.

T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffman, M. Breede, M. Hofmann, G. Hain, K. Pierz, M. Sperling, and K. Donhuijsen, "Continuous-wave THz imaging," Electron. Lett. 37, 1461-1463 (2001).
[CrossRef]

Prather, D. W.

C. A. Schuetz and D. W. Prather, "Optical upconversion techniques for high-sensitivity millimeter-wave detection," in Proc. SPIE 5619, 166-174 (2004).
[CrossRef]

Quast, H.

T. Loffler, K. J. Siebert, H. Quast, N. Hasegawa, G. Lota, R. Wipe, T. Hahn, M. Thomson, R. Leonhardt, and H. G. Roskos, "All-optoelectronic continuous-wave terahertz systems," Philos. Trans. R. Soc. London, Ser. A 362, 263-265 (2004).
[CrossRef]

K. J. Siebert, T. Loffler, H. Quast, M. Thomason, T. Bauer, R. Leonhardt, S. Czasch, and H. G. Roskos, "All optoelectronic continuous wave THz imaging for biomedical applications," Phys. Med. Biol. 47, 2743-2750 (2002).
[CrossRef]

K. J. Siebert, H. Quast, R. Leonhardt, T. Loffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, "Continuous-wave all-optoelectronic terahertz imaging," Appl. Phys. Lett. 80, 3003-3005 (2002).
[CrossRef]

Reiten, M. T.

K. McKlatchy, M. T. Reiten, and R. A. Cheville, "Time resolved synthetic aperture terahertz impulse imaging," Appl. Phys. Lett. 79, 4485-4487 (2001).
[CrossRef]

Roskos, H. G.

T. Loffler, K. J. Siebert, H. Quast, N. Hasegawa, G. Lota, R. Wipe, T. Hahn, M. Thomson, R. Leonhardt, and H. G. Roskos, "All-optoelectronic continuous-wave terahertz systems," Philos. Trans. R. Soc. London, Ser. A 362, 263-265 (2004).
[CrossRef]

K. J. Siebert, H. Quast, R. Leonhardt, T. Loffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, "Continuous-wave all-optoelectronic terahertz imaging," Appl. Phys. Lett. 80, 3003-3005 (2002).
[CrossRef]

K. J. Siebert, T. Loffler, H. Quast, M. Thomason, T. Bauer, R. Leonhardt, S. Czasch, and H. G. Roskos, "All optoelectronic continuous wave THz imaging for biomedical applications," Phys. Med. Biol. 47, 2743-2750 (2002).
[CrossRef]

Rudd, J. V.

Ruffin, A. B.

Ryzhii, V.

V. Ryzhii, I. Khmyrova, and M. Shur, "Terahertz photomixing in quantum well structures using resonant excitation of plasma oscillations," J. Appl. Phys. 91, 1875-1881 (2002).
[CrossRef]

V. Ryzhii, I. Khmyrova, A. Satou, P. O. Vaccaro, T. Aida, and M. Shur, "Plasma mechanism of terahertz photomixing in high-electron mobility transistor under interband photoexcitation," J. Appl. Phys. 92, 5756-5760 (2002).
[CrossRef]

Saki, K.

M. Tani, P. Gu, M. Hyodo, K. Saki, and T. Hidaka, "Generation of coherent terahertz radiation by photomixing of dual-mode lasers," Opt. Quantum Electron. 32, 503-520 (2000).
[CrossRef]

Sanchez-Palencia, L.

Satou, A.

V. Ryzhii, I. Khmyrova, A. Satou, P. O. Vaccaro, T. Aida, and M. Shur, "Plasma mechanism of terahertz photomixing in high-electron mobility transistor under interband photoexcitation," J. Appl. Phys. 92, 5756-5760 (2002).
[CrossRef]

Sauerwald, A.

A. Malcoci, A. Stohr, A. Sauerwald, S. Schulz, and D. Jager, "Waveguide and antenna coupled traveling-wave 1.55 μm photodetectors for optical (sub)millimeter-wave generation," in Proc. SPIE 5466, 202-209 (2004).
[CrossRef]

Schuetz, C. A.

C. A. Schuetz and D. W. Prather, "Optical upconversion techniques for high-sensitivity millimeter-wave detection," in Proc. SPIE 5619, 166-174 (2004).
[CrossRef]

Schulkin, B.

See for example J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, "THz imaging and sensing for security applications—explosives, weapons, and drugs," Semicond. Sci. Technol. 20, S266-S280 (2005); http://stacks.iop.org/0268-1242/20/S266 and references therein.
[CrossRef]

K. P. Walsh, B. Schulkin, D. Gary, J. F. Federici, R. Barat, and D. Zimdars, "Terahertz near-field interferometric and synthetic aperture imaging," in Proc. SPIE 5411, 9-17 (2004).
[CrossRef]

J. F. Federici, D. Gary, B. Schulkin, F. Huang, H. Altan, R. Barat, and D. Zimdars, "Terahertz imaging using an interferometric array," Appl. Phys. Lett. 83, 2477-2479 (2003).
[CrossRef]

Schulz, S.

A. Malcoci, A. Stohr, A. Sauerwald, S. Schulz, and D. Jager, "Waveguide and antenna coupled traveling-wave 1.55 μm photodetectors for optical (sub)millimeter-wave generation," in Proc. SPIE 5466, 202-209 (2004).
[CrossRef]

Shur, M.

V. Ryzhii, I. Khmyrova, A. Satou, P. O. Vaccaro, T. Aida, and M. Shur, "Plasma mechanism of terahertz photomixing in high-electron mobility transistor under interband photoexcitation," J. Appl. Phys. 92, 5756-5760 (2002).
[CrossRef]

V. Ryzhii, I. Khmyrova, and M. Shur, "Terahertz photomixing in quantum well structures using resonant excitation of plasma oscillations," J. Appl. Phys. 91, 1875-1881 (2002).
[CrossRef]

Siebert, K. J.

T. Loffler, K. J. Siebert, H. Quast, N. Hasegawa, G. Lota, R. Wipe, T. Hahn, M. Thomson, R. Leonhardt, and H. G. Roskos, "All-optoelectronic continuous-wave terahertz systems," Philos. Trans. R. Soc. London, Ser. A 362, 263-265 (2004).
[CrossRef]

K. J. Siebert, T. Loffler, H. Quast, M. Thomason, T. Bauer, R. Leonhardt, S. Czasch, and H. G. Roskos, "All optoelectronic continuous wave THz imaging for biomedical applications," Phys. Med. Biol. 47, 2743-2750 (2002).
[CrossRef]

K. J. Siebert, H. Quast, R. Leonhardt, T. Loffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, "Continuous-wave all-optoelectronic terahertz imaging," Appl. Phys. Lett. 80, 3003-3005 (2002).
[CrossRef]

Sperling, M.

T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffman, M. Breede, M. Hofmann, G. Hain, K. Pierz, M. Sperling, and K. Donhuijsen, "Continuous-wave THz imaging," Electron. Lett. 37, 1461-1463 (2001).
[CrossRef]

Stohr, A.

A. Malcoci, A. Stohr, A. Sauerwald, S. Schulz, and D. Jager, "Waveguide and antenna coupled traveling-wave 1.55 μm photodetectors for optical (sub)millimeter-wave generation," in Proc. SPIE 5466, 202-209 (2004).
[CrossRef]

Swenson, G. W.

A. R. Thompson, J. M. Moran, and G. W. Swenson,Interferometry and Synthesis in Radio Astronomy, 2nd ed. (Wiley, 2001), p. 50.
[CrossRef]

Symes, W. W.

Taday, P. F.

W. R. Tribe, D. A. Newnham, P. F. Taday, and M. C. Kemp, "Hidden object detection: security applications of terahertz technology," in Proc. SPIE 5354, 168-176 (2004).
[CrossRef]

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, "Security applications of terahertz technology," in Proc. SPIE 5070, 44-52 (2003).
[CrossRef]

Tani, M.

M. Tani, P. Gu, M. Hyodo, K. Saki, and T. Hidaka, "Generation of coherent terahertz radiation by photomixing of dual-mode lasers," Opt. Quantum Electron. 32, 503-520 (2000).
[CrossRef]

Thomason, M.

K. J. Siebert, T. Loffler, H. Quast, M. Thomason, T. Bauer, R. Leonhardt, S. Czasch, and H. G. Roskos, "All optoelectronic continuous wave THz imaging for biomedical applications," Phys. Med. Biol. 47, 2743-2750 (2002).
[CrossRef]

Thompson, A. R.

A. R. Thompson, J. M. Moran, and G. W. Swenson,Interferometry and Synthesis in Radio Astronomy, 2nd ed. (Wiley, 2001), p. 50.
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M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, "Security applications of terahertz technology," in Proc. SPIE 5070, 44-52 (2003).
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T. Loffler, K. J. Siebert, H. Quast, N. Hasegawa, G. Lota, R. Wipe, T. Hahn, M. Thomson, R. Leonhardt, and H. G. Roskos, "All-optoelectronic continuous-wave terahertz systems," Philos. Trans. R. Soc. London, Ser. A 362, 263-265 (2004).
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See for example J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, "THz imaging and sensing for security applications—explosives, weapons, and drugs," Semicond. Sci. Technol. 20, S266-S280 (2005); http://stacks.iop.org/0268-1242/20/S266 and references therein.
[CrossRef]

D. Zimdars and J. S. White, "Terahertz reflection imaging for package and personnel inspection," in Proc. SPIE 5411, 78-83 (2004).
[CrossRef]

K. P. Walsh, B. Schulkin, D. Gary, J. F. Federici, R. Barat, and D. Zimdars, "Terahertz near-field interferometric and synthetic aperture imaging," in Proc. SPIE 5411, 9-17 (2004).
[CrossRef]

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[CrossRef]

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D. A. Zimdars, "Fiber-pigtailed terahertz time-domain spectroscopy instrumentation for package inspection and security imaging," in Proc. SPIE 5070, 108-116 (2003).
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[CrossRef]

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[CrossRef]

S. Verghese, K. A. McIntosh, and E. R. Brown, "Optical and terahertz power limits in the low-temperature-grown GaAs photomixers," Appl. Phys. Lett. 71, 2743-2745(1997).
[CrossRef]

A. Nahata, J. T. Yardley, and T. F. Heinz, "Two-dimensional imaging of continuous-wave terahertz radiation using electro-optic detection," Appl. Phys. Lett. 81, 963-965 (2002).
[CrossRef]

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[CrossRef]

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[CrossRef]

J. Appl. Phys. (2)

V. Ryzhii, I. Khmyrova, and M. Shur, "Terahertz photomixing in quantum well structures using resonant excitation of plasma oscillations," J. Appl. Phys. 91, 1875-1881 (2002).
[CrossRef]

V. Ryzhii, I. Khmyrova, A. Satou, P. O. Vaccaro, T. Aida, and M. Shur, "Plasma mechanism of terahertz photomixing in high-electron mobility transistor under interband photoexcitation," J. Appl. Phys. 92, 5756-5760 (2002).
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[CrossRef]

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[CrossRef]

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[CrossRef]

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[CrossRef]

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, "Security applications of terahertz technology," in Proc. SPIE 5070, 44-52 (2003).
[CrossRef]

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[CrossRef]

C. A. Schuetz and D. W. Prather, "Optical upconversion techniques for high-sensitivity millimeter-wave detection," in Proc. SPIE 5619, 166-174 (2004).
[CrossRef]

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[CrossRef]

Semicond. Sci. Technol. (1)

See for example J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, "THz imaging and sensing for security applications—explosives, weapons, and drugs," Semicond. Sci. Technol. 20, S266-S280 (2005); http://stacks.iop.org/0268-1242/20/S266 and references therein.
[CrossRef]

Other (7)

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S. M. Duffy, S. Verghese, and K. A. McIntosh,"Photomixers for continuous-wave terahertz radiation," in Sensing with Terahertz Radiation, D.Mittleman, ed. (Springer, 2002).

M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge U. Press, 1999), pp. 574-579.

D. H. Johnson and D. E. Dungeon, Array Signal Processing (Prentice Hall, 1993), pp. 114-115.

A. R. Thompson, J. M. Moran, and G. W. Swenson,Interferometry and Synthesis in Radio Astronomy, 2nd ed. (Wiley, 2001), p. 50.
[CrossRef]

D.L.Woolard, W.R.Loerop, and M.Shur, eds., Terahertz Sensing Technology, Vol. 2: Emerging Scientific Applications & Novel Device Concepts (World Scientific, 2003).

D.Mittleman, ed., Sensing with Terahertz Radiation (Springer, 2003).

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Figures (14)

Fig. 1
Fig. 1

(a) Parallel wavefronts incident on a planar arrangement of detectors. The wavefront is detected simultaneously at all detectors indicating the presence of a point source at infinite distance from the detection array. (b) For a THz source at finite distance D from the detector array, the wave fronts are curved. There is a phase delay between the different detectors as they sample the wavefront. Since the standard Fourier inversion procedure of interferometric imaging assumes planar wavefronts, the reconstructed image is distorted. (c) By adjusting the placement of the detectors to match the circular wavefronts, the detectors detect the same wavefronts simultaneously. This configuration (a point source at finite distance D) is analogous to a planar arrangement of detectors with the source at infinity [Fig. 1a].

Fig. 2
Fig. 2

Source d S on surface of z = z plane irradiating a pair of detectors on the imaging array plane located at ( x 1 , y 1 , Z 0 ) and ( x 2 , y 1 , Z 0 ) .

Fig. 3
Fig. 3

Element of surface d S producing wavefronts at two points on the surface of a spherical array. The detectors are located at spherical coordinates ( R 0 , ϕ 1 , θ 1 ) and ( R 0 , ϕ 2 , θ 2 ) . ( R 0 , ϕ 1 , θ 1 ) denote the distance from the point to the origin, the angle relative to the x axis in the x y plane, and the angle relative to the z axis, respectively.

Fig. 4
Fig. 4

Schematic representation of interferometric imaging array receiver. Two infrared lasers power the THz photo-mixer receivers through fiber-optic cables.

Fig. 5
Fig. 5

Schematic diagram of cw photo-mixing apparatus.

Fig. 6
Fig. 6

Geometry and location of detector array positions (solid squares) and source location (point O at an angle of θ) for near-field correction. For the near-field correction, the appropriate phase is added to the measured THz phase such that the position of the detectors is moved from the line of solid squares to positions (open squares) along the curved path. The radius of curvature of the curved path is R 0 . The distance from the source to each detector position ( x n ) is given by R n . The value of x 0 represents distance from the x n = 0 detector to the origin.

Fig. 7
Fig. 7

(a) Homodyne waveform as acquired by changing the separation between the Tx and Rx in Fig. 5. The solid curve shows a numerical fit to the data. The fundamental extracted frequency, 0.535 THz , compares well with the expected frequency based on the frequency difference of the two ECDL lasers. The extracted E field amplitudes and phases are 3.37 × 10 4 and 2.17 radians for 0.535 THz and 5.61 × 10 5 and 3.94 radians for the 1.605 THz third harmonic, respectively. (b) A similar waveform is obtained with an ECDL difference frequency of 0.354 THz .

Fig. 8
Fig. 8

Symbols represent the data that are extracted from the homodyne waveforms (e.g., Fig. 7). The solid curves are theoretical values assuming that the source is a point source located at R 0 (i.e., incoming spherical waves of constant amplitude). (a) The measured THz amplitude as a function of lateral detector position. (b) The measured phase as a function of lateral detector position. The extracted parameters from Eq. (8) for R 0 , x 0 , θ, and ϕ off are 14.4 cm , 0.275 cm , 0.29°, and 3.38 radians, respectively.

Fig. 9
Fig. 9

(a) Reconstructed image of 0.535 THz source located directly in front of the detector a distance of 14.4 cm away. The dashed curve is the expected image reconstruction assuming a point source at infinity ( FWHM = 4.8 ° ) . (b) Similar reconstructed image for 1.602 THz . Note that the resolution of the central peak FWHM = 1.6 ° is improved by a factor of three corresponding to a 1 3 reduction in the THz wavelength.

Fig. 10
Fig. 10

Measured THz amplitude (a) and phase (b) as a function of lateral detector position in the imaging array. The measured THz phase (diamonds) can be well fitted (solid curve) assuming a point source. The extracted parameters from Eq. (8) for R 0 , x 0 , θ, and ϕ off are 40.9 cm , 0.520 cm , 0.01°, and 1.55 radians, respectively. The curvature of the phase (b) is indicative of spherical THz wavefronts. The corrected phase (measured minus theoretical fit) is indicated by squares.

Fig. 11
Fig. 11

Similar figure to Fig. 10b. The diamonds are the unwrapped phases extracted from the homodyne waveforms. The curvature of the data is indicative of a curved wavefront while the tilted slope is indicative of an inclined wavefront. The triangles represent the near-field correction [from Figure 10b]. The squares represent the near-field corrected phase. The curvature of the phase as a function of lateral detector position has been removed by the near-field correction.

Fig. 12
Fig. 12

(a) Comparison of a reconstructed line image (solid curve) without near-field correction and theoretical image (dashed curve) for a point source at infinity. (b) Comparison of reconstructed line image (solid curve) including a near-field correction. The measured FWHM of 0.6° is about an order of magnitude smaller than in Fig. 9a corresponding to a factor of 10 increase in the largest baseline.

Fig. 13
Fig. 13

(a) Comparison of the image of an ideal point source with constant amplitude (dashed curve) with the experimental data (solid curve). (b) Comparison of the experimental image (solid curve) with a theoretical image (dashed curve) where only a near-field correction to the phase has been applied, while the (nonconstant) amplitudes were used as measured.

Fig. 14
Fig. 14

(a) Comparison of a reconstructed line image (solid curve) without near-field correction and theoretical point image (dashed curve) for the data of Fig. 11. (b) Comparison of reconstructed line image (solid curve) including a near-field correction.

Tables (1)

Tables Icon

Table 1 Estimated Phase Error δ in Imaging a 2.5 cm Object at Various Distances Using 1 THz Radiation

Equations (12)

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d E 1 = ( ψ 0 r 1 ) exp ( i ω t i k r 1 ) d S ,
d E 2 = ( ψ 0 r 2 ) exp ( i ω t i k r 2 ) d S ,
r j = [ ( x x j ) 2 + ( y y j ) 2 + Z 0 2 ] 1 2 .
C 1 , 2 = S σ E ( x , y ) exp [ i k ( r 1 r 2 ) ] r 1 r 2 d S ,
r 1 r 2 = x 1 2 x 2 2 + y 1 2 y 2 2 2 Z 0 + ( x 2 x 1 ) x + ( y 2 y 1 ) y Z 0 .
C 1 , 2 ( u , v ) = exp ( i δ ) σ E ( ξ , η ) exp [ i 2 π ( u ξ + v η ) ] d ξ d η ,
C 1 , 2 = exp i δ ¯ σ E ( ξ , η ) exp ( i 2 π ( u ξ + v η ) ) d ξ d η ,
ϕ = k ( R ( R 0 tan θ ) 2 + R 0 2 ) + ϕ off ,
σ E ( ξ ) = i = 1 N ( N 1 ) 2 { Re [ C ( u i ) ] cos ( 2 π u i ξ ) Im [ C ( u i ) ] sin ( 2 π u i ξ ) } ,
u i = ( x n x m ) λ ,
C ( u i ) = A i e i Δ ϕ i ,
x n = 0.125 ( 1.7 n 1.7 6 ) .

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