Abstract

We have measured the enhanced transmission properties of periodic arrays of subwavelength apertures fabricated in thin metal films as a function of the metal film thickness. In doing so, we determine the minimum metal film thickness for an array that exhibits resonantly enhanced transmission and observe the transmission properties as the metal film thickness is increased. The thickness range explored extends from δ/15, where δ is the skin depth, to approximately 2δ. Using terahertz time-domain spectroscopy, we measure both the amplitude and phase of the transmitted broadband THz pulses. Experimentally, we find that there is negligible transmission enhancement for metal films as thin as δ/15. As the film thickness increases, there is a sublinear increase in the enhancement until the film thickness is equal to the skin depth. For metal films thicker than one skin depth, there appears to be little additional enhancement at the resonant frequencies. We also observe that as the thickness of metal films increases, there is a corresponding increase in the resonance frequencies.

© 2005 Optical Society of America

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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]

Appl. Opt. (1)

Appl. Phys. Lett. (1)

D.E. Grupp, H.J. Lezec, T.W. Ebbesen, K.M. Pellerin, and T. Thio, “Crucial role of metal surface in enhanced transmission through subwavelength apertures,” Appl. Phys. Lett. 77, 1569-1571 (2000).
[CrossRef]

J. Opt. Soc. Am. B (1)

Nature (1)

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

Opt. Express (5)

N. Bonod, S. Enoch, L. Li, P. Evgeny, and M. Neviere, "Resonant optical transmission through thin metallic films with and without holes," Opt. Express 11, 482-490 (2003), <a href="http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-5-482">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-5-482</a>.

H. Cao and A. Nahata, "Resonantly enhanced transmission of terahertz radiation through a periodic array of subwavelength apertures," Opt. Express 12, 1004-1010 (2004), <a href="http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-6-1004">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-6-1004</a>.
[CrossRef]

H. Cao and A. Nahata, "Influence of aperture shape on the transmission properties of a periodic array of subwavelength apertures," Opt. Express 12, 3664-3672 (2004), <a href="http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-16-3664">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-16-3664</a>.
[CrossRef]

A. Degiron and T. W. Ebbesen, "Analysis of the transmission process through single apertures surrounded by periodic corrugations," Opt. Express 12, 3694-3700 (2004), <a href="http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-16-3694">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-16-3694</a>.
[CrossRef]

A. Agrawal, H. Cao, and A. Nahata, "Time-domain analysis of enhanced transmission through a single subwavelength aperture," Opt. Express 13, 3535-3542 (2005), <a href="http://www.opticsexpress.org/abstract.cfm?URI=OPEX-13-9-3535">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-13-9-3535</a>.
[CrossRef]

Opt. Lett. (1)

Phys. Rev. B (1)

H.F. Ghaemi, T. Thio, D.E. Grupp, T.W. Ebbesen, and H.J. Lezec, “Surface plasmons enhance optical transmission through subwavelength holes,” Phys. Rev. B 83, 6779-6782 (1998).

Phys. Rev. Lett. (3)

K.J.K. Koerkamp, S. Enoch, F.B. Segerink, N.F. van Hulst, and L. Kuipers, “Strong influence of hole shape on extraordinary transmission through periodic arrays of subwavelength holes,” Phys. Rev. Lett. 92, 183901/1-4 (2004).
[CrossRef]

R. Gordon, A.G. Brolo, A. McKinnon, A. Rajora, B. Leatham, and K.L. Kavanagh, “Strong polarization in the optical transmission through elliptical nanohole arrays,” Phys. Rev. Lett. 92, 037401 (2004).
[CrossRef]

D. Qu, D. Grischkowsky, “Observation of a new type of THz resonance of surface plasmons propagating on metal-film hole arrays,” Phys. Rev. Lett. 93, 196804/1-4 (2004).
[CrossRef]

Other (2)

D. Grischkowsky, in Frontiers in Nonlinear Optics, edited by H. Walther, N. Koroteev, and M.O. Scully (Institute of Physics Publishing, Philadelphia, 1992) and references therein.

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

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