Abstract

We describe the experimental realization of planar plasmonic THz guided-wave devices using periodically perforated metal films. These perforated films behave as effective media for which the dielectric function can be broadly engineered. We initially use transmission measurements to measure the complex dielectric constants of these effective media and show experimentally that the effective plasma frequency corresponds to the cutoff frequency of the rectangular apertures. Using these structures, we demonstrate not only straight planar THz waveguides, but also more complex devices such as Y-splitters and 3-dB couplers. In each of these embodiments, we demonstrate that the propagating THz radiation is well confined in both the in-plane and out-of-plane axes. This approach opens exciting new avenues for both passive and active THz guided-wave devices and circuits.

© 2008 Optical Society of America

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  1. S. P. Jamison, R. W. McGowan, and D. Grischkowsky, "Single-mode waveguide propagation and reshaping of sub-ps terahertz pulses in sapphire fiber," Appl. Phys. Lett. 76, 1987-1989 (2000).
    [CrossRef]
  2. H. Han, H. Park, M. Cho, and J. Kim, "Terahertz pulse propagation in a plastic photonic crystal fiber," Appl. Phys. Lett. 80, 2634-2636 (2002).
    [CrossRef]
  3. R. Mendis and D. Grischkowsky, "Undistorted guided wave propagation of sub-picosecond THz pulses," Opt. Lett. 26, 846-848 (2001).
    [CrossRef]
  4. J. A. Harrington, R. George, P. Pedersen, and E. Mueller, "Hollow polycarbonate waveguides with inner Cu coatings for delivery of terahertz radiation," Opt. Express 12, 5263-5268 (2004).
    [CrossRef] [PubMed]
  5. K. Wang and D. M. Mittleman, "Metal wires for terahertz wave guiding," Nature 432, 376 (2004).
    [CrossRef] [PubMed]
  6. M. Nagel, A. Marchewka and H. Kurz, "Low-index discontinuity terahertz waveguides," Opt. Express 14, 9944-9954 (2006).
    [CrossRef] [PubMed]
  7. M. A. Ordal, L. L. Long, R. J. Bell, S. E. Bell, R. R. Bell, R. W. Alexander, Jr., and C. A. Ward, "Optical properties of the metals Al, Co, Cu, Au, Fe, Pb, Ni, Pd, Pt, Ag, Ti, and W in the infrared and far infrared," Appl. Opt. 22, 1099-1120 (1983).
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    [CrossRef]
  10. W. Zhu and A. Nahata, "Electric field vector characterization of terahertz surface plasmons," Opt. Express 15, 5616-5624 (2007).
    [CrossRef] [PubMed]
  11. J. B. Pendry, L. Martin-Moreno, and F. J. Garcia-Vidal, "Mimicking surface plasmons with structured surfaces," Science 305, 847-848 (2004).
    [CrossRef] [PubMed]
  12. F. J. Garcia-Vidal, L. Martin-Moreno, and J. B. Pendry, "Surfaces with holes in them: new plasmonic metamaterials," J. Opt. A: Pure Appl. Opt. 7, S97-S101 (2005).
    [CrossRef]
  13. S. A. Maier and S. R. Andrews, "Terahertz pulse propagation using plasmon-polariton-like surface modes on structured conductive surfaces," Appl. Phys. Lett. 88, 251120 (2006).
    [CrossRef]
  14. J. T. Shen, P. B. Catrysse, and S. Fan, "Mechanism for designing metallic metamaterials with a high index of refraction," Phys. Rev. Lett. 94, 197401 (2005).
    [CrossRef] [PubMed]
  15. Z. Ruan and M. Qiu, "Slow electromagnetic wave guided in subwavelength region along one-dimensional periodically structured metal surface," Appl. Phys. Lett. 90, 201906 (2007).
    [CrossRef]
  16. Y. Shin, J. So, J. Won, and G. Park, "Frequency-dependent refractive index of one-dimensionally structured thick metal film," Appl. Phys. Lett. 91, 031102 (2007).
    [CrossRef]
  17. N. Marcuvitz, Waveguide Handbook (New York: McGraw-Hill, 1951).
  18. T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature 391, 667-669 (1998).
    [CrossRef]
  19. L. Duvillaret, F. Garet, and J. Coutaz, "A reliable method for extraction of material parameters in terahertz time-domain spectroscopy," IEEE J. Sel. Tops. Quantum Electron. 2, 739-746 (1996).
    [CrossRef]
  20. W. Zhu, A. Agrawal, and A. Nahata, "Direct measurement of the Gouy phase shift for surface plasmon-polaritons," Opt. Express 15, 9995-10001 (2007).
    [CrossRef] [PubMed]
  21. A. Agrawal, H. Cao, and A. Nahata, "Excitation and scattering of surface plasmon-polaritons on structured metal films and their application to pulse shaping and enhanced transmission," New J. Phys.  7, 249 (2005).
    [CrossRef]
  22. A. Agrawal, T. Matsui, Z. V. Vardeny, and A. Nahata, "Terahertz transmission properties of quasiperiodic and aperiodic aperture arrays," J. Opt. Soc. Am. B 24, 2545-2555 (2007).
    [CrossRef]
  23. C. R. Williams, S. R. Andrews, S. A. Maier, A. I. Fernández-Domínguez, L. Martín-Moreno and F. J. García-Vidal, "Highly confined guiding of terahertz surface plasmon polaritons on structured metal surfaces," Nature Photonics 2, 175-179 (2008).
    [CrossRef]
  24. K. Okamoto, Fundamentals of Optical Waveguides, (Academic Press, New York, 2005).

2008

C. R. Williams, S. R. Andrews, S. A. Maier, A. I. Fernández-Domínguez, L. Martín-Moreno and F. J. García-Vidal, "Highly confined guiding of terahertz surface plasmon polaritons on structured metal surfaces," Nature Photonics 2, 175-179 (2008).
[CrossRef]

2007

2006

S. A. Maier and S. R. Andrews, "Terahertz pulse propagation using plasmon-polariton-like surface modes on structured conductive surfaces," Appl. Phys. Lett. 88, 251120 (2006).
[CrossRef]

M. Nagel, A. Marchewka and H. Kurz, "Low-index discontinuity terahertz waveguides," Opt. Express 14, 9944-9954 (2006).
[CrossRef] [PubMed]

T.-I. Jeon and D. Grischkowsky, "THz Zenneck surface wave (THz surface plasmon) propagation on a metal sheet," Appl. Phys. Lett. 88, 061113 (2006).
[CrossRef]

2005

J. T. Shen, P. B. Catrysse, and S. Fan, "Mechanism for designing metallic metamaterials with a high index of refraction," Phys. Rev. Lett. 94, 197401 (2005).
[CrossRef] [PubMed]

F. J. Garcia-Vidal, L. Martin-Moreno, and J. B. Pendry, "Surfaces with holes in them: new plasmonic metamaterials," J. Opt. A: Pure Appl. Opt. 7, S97-S101 (2005).
[CrossRef]

A. Agrawal, H. Cao, and A. Nahata, "Excitation and scattering of surface plasmon-polaritons on structured metal films and their application to pulse shaping and enhanced transmission," New J. Phys.  7, 249 (2005).
[CrossRef]

2004

J. B. Pendry, L. Martin-Moreno, and F. J. Garcia-Vidal, "Mimicking surface plasmons with structured surfaces," Science 305, 847-848 (2004).
[CrossRef] [PubMed]

J. A. Harrington, R. George, P. Pedersen, and E. Mueller, "Hollow polycarbonate waveguides with inner Cu coatings for delivery of terahertz radiation," Opt. Express 12, 5263-5268 (2004).
[CrossRef] [PubMed]

K. Wang and D. M. Mittleman, "Metal wires for terahertz wave guiding," Nature 432, 376 (2004).
[CrossRef] [PubMed]

2002

H. Han, H. Park, M. Cho, and J. Kim, "Terahertz pulse propagation in a plastic photonic crystal fiber," Appl. Phys. Lett. 80, 2634-2636 (2002).
[CrossRef]

2001

2000

S. P. Jamison, R. W. McGowan, and D. Grischkowsky, "Single-mode waveguide propagation and reshaping of sub-ps terahertz pulses in sapphire fiber," Appl. Phys. Lett. 76, 1987-1989 (2000).
[CrossRef]

1998

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature 391, 667-669 (1998).
[CrossRef]

1996

L. Duvillaret, F. Garet, and J. Coutaz, "A reliable method for extraction of material parameters in terahertz time-domain spectroscopy," IEEE J. Sel. Tops. Quantum Electron. 2, 739-746 (1996).
[CrossRef]

1983

Agrawal, A.

Alexander, R. W.

Andrews, S. R.

C. R. Williams, S. R. Andrews, S. A. Maier, A. I. Fernández-Domínguez, L. Martín-Moreno and F. J. García-Vidal, "Highly confined guiding of terahertz surface plasmon polaritons on structured metal surfaces," Nature Photonics 2, 175-179 (2008).
[CrossRef]

S. A. Maier and S. R. Andrews, "Terahertz pulse propagation using plasmon-polariton-like surface modes on structured conductive surfaces," Appl. Phys. Lett. 88, 251120 (2006).
[CrossRef]

Bell, R. J.

Bell, R. R.

Bell, S. E.

Cao, H.

A. Agrawal, H. Cao, and A. Nahata, "Excitation and scattering of surface plasmon-polaritons on structured metal films and their application to pulse shaping and enhanced transmission," New J. Phys.  7, 249 (2005).
[CrossRef]

Catrysse, P. B.

J. T. Shen, P. B. Catrysse, and S. Fan, "Mechanism for designing metallic metamaterials with a high index of refraction," Phys. Rev. Lett. 94, 197401 (2005).
[CrossRef] [PubMed]

Cho, M.

H. Han, H. Park, M. Cho, and J. Kim, "Terahertz pulse propagation in a plastic photonic crystal fiber," Appl. Phys. Lett. 80, 2634-2636 (2002).
[CrossRef]

Coutaz, J.

L. Duvillaret, F. Garet, and J. Coutaz, "A reliable method for extraction of material parameters in terahertz time-domain spectroscopy," IEEE J. Sel. Tops. Quantum Electron. 2, 739-746 (1996).
[CrossRef]

Duvillaret, L.

L. Duvillaret, F. Garet, and J. Coutaz, "A reliable method for extraction of material parameters in terahertz time-domain spectroscopy," IEEE J. Sel. Tops. Quantum Electron. 2, 739-746 (1996).
[CrossRef]

Ebbesen, T. W.

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature 391, 667-669 (1998).
[CrossRef]

Fan, S.

J. T. Shen, P. B. Catrysse, and S. Fan, "Mechanism for designing metallic metamaterials with a high index of refraction," Phys. Rev. Lett. 94, 197401 (2005).
[CrossRef] [PubMed]

Fernández-Domínguez, A. I.

C. R. Williams, S. R. Andrews, S. A. Maier, A. I. Fernández-Domínguez, L. Martín-Moreno and F. J. García-Vidal, "Highly confined guiding of terahertz surface plasmon polaritons on structured metal surfaces," Nature Photonics 2, 175-179 (2008).
[CrossRef]

Garcia-Vidal, F. J.

F. J. Garcia-Vidal, L. Martin-Moreno, and J. B. Pendry, "Surfaces with holes in them: new plasmonic metamaterials," J. Opt. A: Pure Appl. Opt. 7, S97-S101 (2005).
[CrossRef]

J. B. Pendry, L. Martin-Moreno, and F. J. Garcia-Vidal, "Mimicking surface plasmons with structured surfaces," Science 305, 847-848 (2004).
[CrossRef] [PubMed]

García-Vidal, F. J.

C. R. Williams, S. R. Andrews, S. A. Maier, A. I. Fernández-Domínguez, L. Martín-Moreno and F. J. García-Vidal, "Highly confined guiding of terahertz surface plasmon polaritons on structured metal surfaces," Nature Photonics 2, 175-179 (2008).
[CrossRef]

Garet, F.

L. Duvillaret, F. Garet, and J. Coutaz, "A reliable method for extraction of material parameters in terahertz time-domain spectroscopy," IEEE J. Sel. Tops. Quantum Electron. 2, 739-746 (1996).
[CrossRef]

George, R.

Ghaemi, H. F.

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature 391, 667-669 (1998).
[CrossRef]

Grischkowsky, D.

T.-I. Jeon and D. Grischkowsky, "THz Zenneck surface wave (THz surface plasmon) propagation on a metal sheet," Appl. Phys. Lett. 88, 061113 (2006).
[CrossRef]

R. Mendis and D. Grischkowsky, "Undistorted guided wave propagation of sub-picosecond THz pulses," Opt. Lett. 26, 846-848 (2001).
[CrossRef]

S. P. Jamison, R. W. McGowan, and D. Grischkowsky, "Single-mode waveguide propagation and reshaping of sub-ps terahertz pulses in sapphire fiber," Appl. Phys. Lett. 76, 1987-1989 (2000).
[CrossRef]

Han, H.

H. Han, H. Park, M. Cho, and J. Kim, "Terahertz pulse propagation in a plastic photonic crystal fiber," Appl. Phys. Lett. 80, 2634-2636 (2002).
[CrossRef]

Harrington, J. A.

Jamison, S. P.

S. P. Jamison, R. W. McGowan, and D. Grischkowsky, "Single-mode waveguide propagation and reshaping of sub-ps terahertz pulses in sapphire fiber," Appl. Phys. Lett. 76, 1987-1989 (2000).
[CrossRef]

Jeon, T.-I.

T.-I. Jeon and D. Grischkowsky, "THz Zenneck surface wave (THz surface plasmon) propagation on a metal sheet," Appl. Phys. Lett. 88, 061113 (2006).
[CrossRef]

Kim, J.

H. Han, H. Park, M. Cho, and J. Kim, "Terahertz pulse propagation in a plastic photonic crystal fiber," Appl. Phys. Lett. 80, 2634-2636 (2002).
[CrossRef]

Kurz, H.

Lezec, H. J.

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature 391, 667-669 (1998).
[CrossRef]

Long, L. L.

Maier, S. A.

C. R. Williams, S. R. Andrews, S. A. Maier, A. I. Fernández-Domínguez, L. Martín-Moreno and F. J. García-Vidal, "Highly confined guiding of terahertz surface plasmon polaritons on structured metal surfaces," Nature Photonics 2, 175-179 (2008).
[CrossRef]

S. A. Maier and S. R. Andrews, "Terahertz pulse propagation using plasmon-polariton-like surface modes on structured conductive surfaces," Appl. Phys. Lett. 88, 251120 (2006).
[CrossRef]

Marchewka, A.

Martin-Moreno, L.

F. J. Garcia-Vidal, L. Martin-Moreno, and J. B. Pendry, "Surfaces with holes in them: new plasmonic metamaterials," J. Opt. A: Pure Appl. Opt. 7, S97-S101 (2005).
[CrossRef]

J. B. Pendry, L. Martin-Moreno, and F. J. Garcia-Vidal, "Mimicking surface plasmons with structured surfaces," Science 305, 847-848 (2004).
[CrossRef] [PubMed]

Martín-Moreno, L.

C. R. Williams, S. R. Andrews, S. A. Maier, A. I. Fernández-Domínguez, L. Martín-Moreno and F. J. García-Vidal, "Highly confined guiding of terahertz surface plasmon polaritons on structured metal surfaces," Nature Photonics 2, 175-179 (2008).
[CrossRef]

Matsui, T.

McGowan, R. W.

S. P. Jamison, R. W. McGowan, and D. Grischkowsky, "Single-mode waveguide propagation and reshaping of sub-ps terahertz pulses in sapphire fiber," Appl. Phys. Lett. 76, 1987-1989 (2000).
[CrossRef]

Mendis, R.

Mittleman, D. M.

K. Wang and D. M. Mittleman, "Metal wires for terahertz wave guiding," Nature 432, 376 (2004).
[CrossRef] [PubMed]

Mueller, E.

Nagel, M.

Nahata, A.

Ordal, M. A.

Park, G.

Y. Shin, J. So, J. Won, and G. Park, "Frequency-dependent refractive index of one-dimensionally structured thick metal film," Appl. Phys. Lett. 91, 031102 (2007).
[CrossRef]

Park, H.

H. Han, H. Park, M. Cho, and J. Kim, "Terahertz pulse propagation in a plastic photonic crystal fiber," Appl. Phys. Lett. 80, 2634-2636 (2002).
[CrossRef]

Pedersen, P.

Pendry, J. B.

F. J. Garcia-Vidal, L. Martin-Moreno, and J. B. Pendry, "Surfaces with holes in them: new plasmonic metamaterials," J. Opt. A: Pure Appl. Opt. 7, S97-S101 (2005).
[CrossRef]

J. B. Pendry, L. Martin-Moreno, and F. J. Garcia-Vidal, "Mimicking surface plasmons with structured surfaces," Science 305, 847-848 (2004).
[CrossRef] [PubMed]

Qiu, M.

Z. Ruan and M. Qiu, "Slow electromagnetic wave guided in subwavelength region along one-dimensional periodically structured metal surface," Appl. Phys. Lett. 90, 201906 (2007).
[CrossRef]

Ruan, Z.

Z. Ruan and M. Qiu, "Slow electromagnetic wave guided in subwavelength region along one-dimensional periodically structured metal surface," Appl. Phys. Lett. 90, 201906 (2007).
[CrossRef]

Shen, J. T.

J. T. Shen, P. B. Catrysse, and S. Fan, "Mechanism for designing metallic metamaterials with a high index of refraction," Phys. Rev. Lett. 94, 197401 (2005).
[CrossRef] [PubMed]

Shin, Y.

Y. Shin, J. So, J. Won, and G. Park, "Frequency-dependent refractive index of one-dimensionally structured thick metal film," Appl. Phys. Lett. 91, 031102 (2007).
[CrossRef]

So, J.

Y. Shin, J. So, J. Won, and G. Park, "Frequency-dependent refractive index of one-dimensionally structured thick metal film," Appl. Phys. Lett. 91, 031102 (2007).
[CrossRef]

Thio, T.

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature 391, 667-669 (1998).
[CrossRef]

Vardeny, Z. V.

Wang, K.

K. Wang and D. M. Mittleman, "Metal wires for terahertz wave guiding," Nature 432, 376 (2004).
[CrossRef] [PubMed]

Ward, C. A.

Williams, C. R.

C. R. Williams, S. R. Andrews, S. A. Maier, A. I. Fernández-Domínguez, L. Martín-Moreno and F. J. García-Vidal, "Highly confined guiding of terahertz surface plasmon polaritons on structured metal surfaces," Nature Photonics 2, 175-179 (2008).
[CrossRef]

Wolff, P. A.

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature 391, 667-669 (1998).
[CrossRef]

Won, J.

Y. Shin, J. So, J. Won, and G. Park, "Frequency-dependent refractive index of one-dimensionally structured thick metal film," Appl. Phys. Lett. 91, 031102 (2007).
[CrossRef]

Zhu, W.

Appl. Opt.

Appl. Phys. Lett.

T.-I. Jeon and D. Grischkowsky, "THz Zenneck surface wave (THz surface plasmon) propagation on a metal sheet," Appl. Phys. Lett. 88, 061113 (2006).
[CrossRef]

S. P. Jamison, R. W. McGowan, and D. Grischkowsky, "Single-mode waveguide propagation and reshaping of sub-ps terahertz pulses in sapphire fiber," Appl. Phys. Lett. 76, 1987-1989 (2000).
[CrossRef]

H. Han, H. Park, M. Cho, and J. Kim, "Terahertz pulse propagation in a plastic photonic crystal fiber," Appl. Phys. Lett. 80, 2634-2636 (2002).
[CrossRef]

S. A. Maier and S. R. Andrews, "Terahertz pulse propagation using plasmon-polariton-like surface modes on structured conductive surfaces," Appl. Phys. Lett. 88, 251120 (2006).
[CrossRef]

Z. Ruan and M. Qiu, "Slow electromagnetic wave guided in subwavelength region along one-dimensional periodically structured metal surface," Appl. Phys. Lett. 90, 201906 (2007).
[CrossRef]

Y. Shin, J. So, J. Won, and G. Park, "Frequency-dependent refractive index of one-dimensionally structured thick metal film," Appl. Phys. Lett. 91, 031102 (2007).
[CrossRef]

IEEE J. Sel. Tops. Quantum Electron.

L. Duvillaret, F. Garet, and J. Coutaz, "A reliable method for extraction of material parameters in terahertz time-domain spectroscopy," IEEE J. Sel. Tops. Quantum Electron. 2, 739-746 (1996).
[CrossRef]

J. Opt. A: Pure Appl. Opt.

F. J. Garcia-Vidal, L. Martin-Moreno, and J. B. Pendry, "Surfaces with holes in them: new plasmonic metamaterials," J. Opt. A: Pure Appl. Opt. 7, S97-S101 (2005).
[CrossRef]

J. Opt. Soc. Am. B

Nature

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature 391, 667-669 (1998).
[CrossRef]

K. Wang and D. M. Mittleman, "Metal wires for terahertz wave guiding," Nature 432, 376 (2004).
[CrossRef] [PubMed]

Nature Photonics

C. R. Williams, S. R. Andrews, S. A. Maier, A. I. Fernández-Domínguez, L. Martín-Moreno and F. J. García-Vidal, "Highly confined guiding of terahertz surface plasmon polaritons on structured metal surfaces," Nature Photonics 2, 175-179 (2008).
[CrossRef]

New J. Phys.

A. Agrawal, H. Cao, and A. Nahata, "Excitation and scattering of surface plasmon-polaritons on structured metal films and their application to pulse shaping and enhanced transmission," New J. Phys.  7, 249 (2005).
[CrossRef]

Opt. Express

Opt. Lett.

Phys. Rev. Lett.

J. T. Shen, P. B. Catrysse, and S. Fan, "Mechanism for designing metallic metamaterials with a high index of refraction," Phys. Rev. Lett. 94, 197401 (2005).
[CrossRef] [PubMed]

Science

J. B. Pendry, L. Martin-Moreno, and F. J. Garcia-Vidal, "Mimicking surface plasmons with structured surfaces," Science 305, 847-848 (2004).
[CrossRef] [PubMed]

Other

H. Raether, Surface Plasmons on Smooth and Rough Surfaces and on Gratings, Springer Tracts in Modern Physics, (Springer-Verlag, Berlin, 1988) Vol. 111.

N. Marcuvitz, Waveguide Handbook (New York: McGraw-Hill, 1951).

K. Okamoto, Fundamentals of Optical Waveguides, (Academic Press, New York, 2005).

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Figures (6)

Fig. 1.
Fig. 1.

Transmission properties of a linear row of periodically spaced rectangular apertures for a TM-polarized incident THz field. (a) Schematic diagram showing the experimental configuration to measure the dielectric properties of the effective plasmonic media. The TM-polarized THz radiation is normally incident on the structured metal film. The dimensions of the apertures are: length s=500 µm, width a=50 µm, periodicity d=250 µm and thickness l=635 µm. The total length of this structure is 8 cm, corresponding to approximately 320 apertures. (b) A top-view photograph of the actual row of apertures. (c) The amplitude transmittance spectra, t(ω)measured using THz time-domain spectroscopy (red trace). The black trace corresponds to the calculated transmittance through an equivalent dispersive dielectric slab using the FDTD technique. (d) The corresponding measured phase spectra φ(ω). (e) Change in the resonance frequencies ωmnp as a function of incident angle θ. The three traces correspond to the different resonances in the perforated medium: TM100 (red), TM101 (blue), and TM102 (black).

Fig. 2.
Fig. 2.

Dielectric properties of a linear row of periodically spaced rectangular apertures (shown in Fig. 1) for a TM-polarized incident THz field. The real and imaginary components of the effective dielectric constant, εreal(ω) and εimag(ω) calculated from the measured t(ω) and φ(ω) spectra shown in Fig. 1. The black traces shows the fit to εreal(ω) and εimag(ω) using the Drude model of Eq. (3).

Fig. 3.
Fig. 3.

Linear waveguiding properties of the planar plasmonic waveguide fabricated using periodically spaced rectangular apertures. (a) Schematic diagram showing the experimental configuration. A semi-circular groove is used to couple a single-cycle THz pulse to a surface wave pulse, which is subsequently focused at the input of the waveguide. The guided wave is then detected by electro-optic sampling using a (110) ZnTe crystal placed at the output of the waveguide. (b) The guided-wave transmission spectrum, tWG(ω) measured after propagation along the entire waveguide (red trace). The black trace corresponds to the guided-wave transmission spectrum calculated using the FDTD technique. (c)–(e) shows the total electric field distributions in the yz-plane in the rectangular aperture, corresponding to the resonance modes of (c) TM100, (d) TM101 and (e) TM102.

Fig. 4.
Fig. 4.

Propagation properties of the TM100 mode in the planar plasmonic waveguide shown in Fig. 3. (a) The field amplitude |Ez| measured along the x-axis at different positions along the length of the waveguide. (b) The |Ez| component of the electric field measured along the y-axis at two different positions along the waveguide: 5 cm and 7 cm from the waveguide input. (c) The |Ez| component of the electric field measured along the z-axis at different heights above the sample surface. It is apparent from the figures that the plasmonic mode propagates with very low-loss and remains tightly confined to the waveguide.

Fig. 5.
Fig. 5.

Passive plasmonic guided-wave Y-splitter fabricated using the effective medium concept. Upper panel - A schematic diagram of the Y-splitter structure; a semi-circular groove is used to couple a free-space THz radiation into the guiding structure. For clarity, the splitter section of the Y-splitter is expanded in the figure panel. Lower panel: The field amplitude |Ez| measured along y-axis at the end of the Y-splitter (red dots), marked as a black dashed line in the upper panel. The solid red trace is a fit to the experimental data using a sum of two spatially offset Gaussian functions.

Fig. 6.
Fig. 6.

Passive plasmonic guided-wave 3-dB coupler fabricated using the effective medium concept. Upper panel: A schematic diagram of the 3-dB coupler structure; again, a semicircular groove is used to couple a free-space THz radiation into the guiding structure. For clarity the coupling section of the 3-dB coupler is expanded in the figure panel. Lower panel: The field amplitude |Ez| measured along y-axis at the end of the 3dB-coupler (red dots), marked as a black dashed line in the upper panel. The solid red trace is a fit to the experimental data using a sum of two spatially offset Gaussian functions.

Equations (5)

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t ( ω ) = t ( ω ) exp [ i φ ( ω ) ] = E transmitted ( ω ) E incident ( ω )
f mnp TM = c 2 π ( m π s ) 2 + ( n π a ) 2 + ( p π 1 ) 2 ,
ε ( ω ) = ε ( 1 ω ~ p 2 ω 2 + i γ ω ) ,
z = 1 α z = Im [ 1 k z ]
z = 1 ( π d ) 2 ( ω c ) 2 .

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