Abstract

We report on layer thickness determination down to a thickness of 2.5 microns using terahertz waveguide spectroscopy. Compared to typical single-pass transmission measurements in the time domain, the effective THz pulse delay is considerably increased for a given layer thickness by using the high filling factor of the THz waveguide. This corresponds to a sensitivity increase up to a factor of 50 for the measured delay, allowing the direct measurement of layer thicknesses down to below hundredths of a THz wavelength.

© 2010 Optical Society of America

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  1. C. am Weg, W.  von Spiegel, R. Henneberger, R. Zimmermann, T. Löffler, and H. G. Roskos, “Fast active THz camera with range detection by frequency modulation,” Proc. SPIE 7215, 72150F (2009).
    [CrossRef]
  2. M. van Exter, and D. R. Grischkowsky, “Characterization of an optoelectronic terahertz beam system,” IEEE Trans. Microw. Theory Tech. 38, 1684–1691 (1990).
    [CrossRef]
  3. D. Grischkowsky, S. Keiding, M. Exter, and C. Fattinger, “Far-Infrared Time-Domain Spectroscopy with Terahertz Beams of Dielectrics and Semiconductors,” J. Opt. Soc. Am. B 7, 2006–2015 (1990).
    [CrossRef]
  4. D. Molter, M. Theuer, and R. Beigang, “Nanosecond terahertz optical parametric oscillator with a novel quasi phase matching scheme in lithium niobate,” Opt. Express 8, 6623–6628 (2009).
    [CrossRef]
  5. D. M. Mittleman, S. Hunsche, L. Boivin, and M. C. Nuss, “T-ray tomography,” Opt. Lett. 22, 904–906 (1997).
    [CrossRef] [PubMed]
  6. B. Hils, M. D. Thomson, T. Löffler, W. von Spiegel, C. am Weg, H. G. Roskos, P. de Maagt, D. Doyle, and R. R. Geckeler “Terahertz profilometry at 600 GHz with 0.5 µm depth resolution,” Opt. Express 16, 11289–11293 (2008).
    [CrossRef] [PubMed]
  7. J. L. Johnson, T. D. Dorney, and D. M. Mittleman, “Enhanced depth resolution in terahertz imaging using phase shift interferometry,” Appl. Phys. Lett. 78, 835–837 (2001).
    [CrossRef]
  8. J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
    [CrossRef]
  9. M. Gong, T. I. Jeon, and D. Grischkowsky, “THz surface wave collapse on coated metal surfaces,” Opt. Express 17, 17088–17101 (2009).
    [CrossRef] [PubMed]
  10. M. Theuer, R. Beigang, and D. Grischkowsky, “Adiabatic Compression of Terahertz Waves using Metal Flares,” Appl. Phys. Lett. (accepted for publication).
  11. R. Mendis, and D. Grischkowsky, “Undistorted guided-wave propagation of subpicosecond terahertz pulses,” Opt. Lett. 26, 846–848 (2001).
    [CrossRef]
  12. R. Mendis, “Nature of subpicosecond terahertz pulse propagation in practical dielectric-filled parallel-plate waveguides,” Opt. Lett. 31, 2643–2645 (2006).
    [CrossRef] [PubMed]
  13. G. Gallot, S. P. Jamison, R. W. McGowan, and D. Grischkowsky, “Terahertz waveguides,” J. Opt. Soc. Am. B 5, 851–863 (2000).
    [CrossRef]

2009 (4)

C. am Weg, W.  von Spiegel, R. Henneberger, R. Zimmermann, T. Löffler, and H. G. Roskos, “Fast active THz camera with range detection by frequency modulation,” Proc. SPIE 7215, 72150F (2009).
[CrossRef]

D. Molter, M. Theuer, and R. Beigang, “Nanosecond terahertz optical parametric oscillator with a novel quasi phase matching scheme in lithium niobate,” Opt. Express 8, 6623–6628 (2009).
[CrossRef]

J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
[CrossRef]

M. Gong, T. I. Jeon, and D. Grischkowsky, “THz surface wave collapse on coated metal surfaces,” Opt. Express 17, 17088–17101 (2009).
[CrossRef] [PubMed]

2008 (1)

2006 (1)

2001 (2)

J. L. Johnson, T. D. Dorney, and D. M. Mittleman, “Enhanced depth resolution in terahertz imaging using phase shift interferometry,” Appl. Phys. Lett. 78, 835–837 (2001).
[CrossRef]

R. Mendis, and D. Grischkowsky, “Undistorted guided-wave propagation of subpicosecond terahertz pulses,” Opt. Lett. 26, 846–848 (2001).
[CrossRef]

2000 (1)

G. Gallot, S. P. Jamison, R. W. McGowan, and D. Grischkowsky, “Terahertz waveguides,” J. Opt. Soc. Am. B 5, 851–863 (2000).
[CrossRef]

1997 (1)

1990 (2)

M. van Exter, and D. R. Grischkowsky, “Characterization of an optoelectronic terahertz beam system,” IEEE Trans. Microw. Theory Tech. 38, 1684–1691 (1990).
[CrossRef]

D. Grischkowsky, S. Keiding, M. Exter, and C. Fattinger, “Far-Infrared Time-Domain Spectroscopy with Terahertz Beams of Dielectrics and Semiconductors,” J. Opt. Soc. Am. B 7, 2006–2015 (1990).
[CrossRef]

Spiegel, W.

C. am Weg, W.  von Spiegel, R. Henneberger, R. Zimmermann, T. Löffler, and H. G. Roskos, “Fast active THz camera with range detection by frequency modulation,” Proc. SPIE 7215, 72150F (2009).
[CrossRef]

am Weg, C.

C. am Weg, W.  von Spiegel, R. Henneberger, R. Zimmermann, T. Löffler, and H. G. Roskos, “Fast active THz camera with range detection by frequency modulation,” Proc. SPIE 7215, 72150F (2009).
[CrossRef]

B. Hils, M. D. Thomson, T. Löffler, W. von Spiegel, C. am Weg, H. G. Roskos, P. de Maagt, D. Doyle, and R. R. Geckeler “Terahertz profilometry at 600 GHz with 0.5 µm depth resolution,” Opt. Express 16, 11289–11293 (2008).
[CrossRef] [PubMed]

Beigang, R.

D. Molter, M. Theuer, and R. Beigang, “Nanosecond terahertz optical parametric oscillator with a novel quasi phase matching scheme in lithium niobate,” Opt. Express 8, 6623–6628 (2009).
[CrossRef]

M. Theuer, R. Beigang, and D. Grischkowsky, “Adiabatic Compression of Terahertz Waves using Metal Flares,” Appl. Phys. Lett. (accepted for publication).

Boivin, L.

de Maagt, P.

Dorney, T. D.

J. L. Johnson, T. D. Dorney, and D. M. Mittleman, “Enhanced depth resolution in terahertz imaging using phase shift interferometry,” Appl. Phys. Lett. 78, 835–837 (2001).
[CrossRef]

Doyle, D.

Exter, M.

Fattinger, C.

Gallot, G.

G. Gallot, S. P. Jamison, R. W. McGowan, and D. Grischkowsky, “Terahertz waveguides,” J. Opt. Soc. Am. B 5, 851–863 (2000).
[CrossRef]

Geckeler, R. R.

Gong, M.

Grischkowsky, D.

Grischkowsky, D. R.

M. van Exter, and D. R. Grischkowsky, “Characterization of an optoelectronic terahertz beam system,” IEEE Trans. Microw. Theory Tech. 38, 1684–1691 (1990).
[CrossRef]

Henneberger, R.

C. am Weg, W.  von Spiegel, R. Henneberger, R. Zimmermann, T. Löffler, and H. G. Roskos, “Fast active THz camera with range detection by frequency modulation,” Proc. SPIE 7215, 72150F (2009).
[CrossRef]

Hils, B.

Hunsche, S.

Ichino, S.

J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
[CrossRef]

Jamison, S. P.

G. Gallot, S. P. Jamison, R. W. McGowan, and D. Grischkowsky, “Terahertz waveguides,” J. Opt. Soc. Am. B 5, 851–863 (2000).
[CrossRef]

Jeon, T. I.

Jinno, H.

J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
[CrossRef]

Johnson, J. L.

J. L. Johnson, T. D. Dorney, and D. M. Mittleman, “Enhanced depth resolution in terahertz imaging using phase shift interferometry,” Appl. Phys. Lett. 78, 835–837 (2001).
[CrossRef]

Kasai, S.

J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
[CrossRef]

Kawase, K.

J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
[CrossRef]

Keiding, S.

Löffler, T.

C. am Weg, W.  von Spiegel, R. Henneberger, R. Zimmermann, T. Löffler, and H. G. Roskos, “Fast active THz camera with range detection by frequency modulation,” Proc. SPIE 7215, 72150F (2009).
[CrossRef]

B. Hils, M. D. Thomson, T. Löffler, W. von Spiegel, C. am Weg, H. G. Roskos, P. de Maagt, D. Doyle, and R. R. Geckeler “Terahertz profilometry at 600 GHz with 0.5 µm depth resolution,” Opt. Express 16, 11289–11293 (2008).
[CrossRef] [PubMed]

McGowan, R. W.

G. Gallot, S. P. Jamison, R. W. McGowan, and D. Grischkowsky, “Terahertz waveguides,” J. Opt. Soc. Am. B 5, 851–863 (2000).
[CrossRef]

Mendis, R.

Mittleman, D. M.

J. L. Johnson, T. D. Dorney, and D. M. Mittleman, “Enhanced depth resolution in terahertz imaging using phase shift interferometry,” Appl. Phys. Lett. 78, 835–837 (2001).
[CrossRef]

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

Molter, D.

D. Molter, M. Theuer, and R. Beigang, “Nanosecond terahertz optical parametric oscillator with a novel quasi phase matching scheme in lithium niobate,” Opt. Express 8, 6623–6628 (2009).
[CrossRef]

Nishizawa, N.

J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
[CrossRef]

Nuss, M. C.

Ohtake, H.

J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
[CrossRef]

Ouchi, T.

J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
[CrossRef]

Roskos, H. G.

C. am Weg, W.  von Spiegel, R. Henneberger, R. Zimmermann, T. Löffler, and H. G. Roskos, “Fast active THz camera with range detection by frequency modulation,” Proc. SPIE 7215, 72150F (2009).
[CrossRef]

B. Hils, M. D. Thomson, T. Löffler, W. von Spiegel, C. am Weg, H. G. Roskos, P. de Maagt, D. Doyle, and R. R. Geckeler “Terahertz profilometry at 600 GHz with 0.5 µm depth resolution,” Opt. Express 16, 11289–11293 (2008).
[CrossRef] [PubMed]

Suizu, K.

J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
[CrossRef]

Takayanagi, J.

J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
[CrossRef]

Theuer, M.

D. Molter, M. Theuer, and R. Beigang, “Nanosecond terahertz optical parametric oscillator with a novel quasi phase matching scheme in lithium niobate,” Opt. Express 8, 6623–6628 (2009).
[CrossRef]

M. Theuer, R. Beigang, and D. Grischkowsky, “Adiabatic Compression of Terahertz Waves using Metal Flares,” Appl. Phys. Lett. (accepted for publication).

Thomson, M. D.

Uchida, H.

J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
[CrossRef]

van Exter, M.

M. van Exter, and D. R. Grischkowsky, “Characterization of an optoelectronic terahertz beam system,” IEEE Trans. Microw. Theory Tech. 38, 1684–1691 (1990).
[CrossRef]

von Spiegel, W.

Yamashita, M.

J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
[CrossRef]

Zimmermann, R.

C. am Weg, W.  von Spiegel, R. Henneberger, R. Zimmermann, T. Löffler, and H. G. Roskos, “Fast active THz camera with range detection by frequency modulation,” Proc. SPIE 7215, 72150F (2009).
[CrossRef]

Appl. Phys. Lett. (2)

J. L. Johnson, T. D. Dorney, and D. M. Mittleman, “Enhanced depth resolution in terahertz imaging using phase shift interferometry,” Appl. Phys. Lett. 78, 835–837 (2001).
[CrossRef]

M. Theuer, R. Beigang, and D. Grischkowsky, “Adiabatic Compression of Terahertz Waves using Metal Flares,” Appl. Phys. Lett. (accepted for publication).

IEEE Trans. Microw. Theory Tech. (1)

M. van Exter, and D. R. Grischkowsky, “Characterization of an optoelectronic terahertz beam system,” IEEE Trans. Microw. Theory Tech. 38, 1684–1691 (1990).
[CrossRef]

J. Opt. Soc. Am. B (2)

Opt. Express (4)

D. Molter, M. Theuer, and R. Beigang, “Nanosecond terahertz optical parametric oscillator with a novel quasi phase matching scheme in lithium niobate,” Opt. Express 8, 6623–6628 (2009).
[CrossRef]

J. Takayanagi, H. Jinno, S. Ichino, K. Suizu, M. Yamashita, T. Ouchi, S. Kasai, H. Ohtake, H. Uchida, N. Nishizawa, and K. Kawase, “High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser,” Opt. Express 9, 7533–7539 (2009).
[CrossRef]

M. Gong, T. I. Jeon, and D. Grischkowsky, “THz surface wave collapse on coated metal surfaces,” Opt. Express 17, 17088–17101 (2009).
[CrossRef] [PubMed]

B. Hils, M. D. Thomson, T. Löffler, W. von Spiegel, C. am Weg, H. G. Roskos, P. de Maagt, D. Doyle, and R. R. Geckeler “Terahertz profilometry at 600 GHz with 0.5 µm depth resolution,” Opt. Express 16, 11289–11293 (2008).
[CrossRef] [PubMed]

Opt. Lett. (3)

Proc. SPIE (1)

C. am Weg, W.  von Spiegel, R. Henneberger, R. Zimmermann, T. Löffler, and H. G. Roskos, “Fast active THz camera with range detection by frequency modulation,” Proc. SPIE 7215, 72150F (2009).
[CrossRef]

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Figures (6)

Fig. 1.
Fig. 1.

Cross section of THz-TDS system used for the investigation of coated cylinders. A parallel-plate waveguide launches the THz surface wave on top of the coated metal sheet waveguide. This guided evanescent field interacts with the dielectric coating T of the metal cylinder. The propagation distance from the output face of the waveguide to the point of closest approach is 14cm, and from that point to the receiver is 8cm. The approach distance d is the free-space separation (air gap) between the coated cylinder and the coated metal sheet.

Fig. 2.
Fig. 2.

Comparison of THz amplitude transmission for a 32mm diameter aluminum cylinder and a 3mm-thick metal plate slit on top of the dielectric coated waveguide. For small approach distances the round cylinder gives rise to a higher transmission than the slit, the adiabatic increase.

Fig. 3.
Fig. 3.

Measured delay for an uncoated, a 12.5μm and a 127μm (Parafilm® M) coated, 32mm diameter metal cylinders as a function of the approach distance d.

Fig. 4.
Fig. 4.

The measured reference electric field (upper trace) is for the undisturbed THz surface wave, the uncoated electric field is for the uncoated 32mm diameter aluminum cylinder. Stepwise layers of PET plastic sheet (Mylar® with 2.5μm thickness) are attached, shown here for 1, 5 and 10 layers, offset for clarity. All cylinders are in contact.

Fig. 5.
Fig. 5.

Delay at contact caused by the 32mm diameter aluminum cylinder on which step-wise layers of Mylar® are attached.

Fig. 6.
Fig. 6.

Theoretically expected delay caused by dielectric coatings on a cylinder of 32mm diameter in contact and within a homogeneous field of 1 mm extent (see inset sketch). The related sensitivity increase is calculated with respect to the single pass delay.

Equations (3)

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δ t = ( n 1 ) T c ,
n eff ( x ) = 1 1 T + S T + d ( x ) + S ( 1 1 n 2 )
Δt = interaction n eff ( x ) 1 c dx .

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