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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 18, Iss. 16 — Aug. 2, 2010
  • pp: 16452–16459

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Giant nonlinear response of terahertz nanoresonators on VO2 thin film

Jisoo Kyoung, Minah Seo, Hyeongryeol Park, Sukmo Koo, Hyun-sun Kim, Youngmi Park, Bong-Jun Kim, Kwangjun Ahn, Namkyoo Park, Hyun-Tak Kim, and Dai-Sik Kim  »View Author Affiliations


Optics Express, Vol. 18, Issue 16, pp. 16452-16459 (2010)
http://dx.doi.org/10.1364/OE.18.016452


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Abstract

We report on an order of magnitude enhanced nonlinear response of vanadium dioxide thin film patterned with nanoresonators – nano slot antennas fabricated on the gold film. Transmission of terahertz radiation, little affected by an optical pumping for the case of bulk thin film, can now be completely switched-off: ΔT/T≈-0.9999 by the same optical pumping power. This unprecedentedly large optical pump-terahertz probe nonlinearity originates from the insulator-to-metal phase transition drastically reducing the antenna cross sections of the nanoresonators. Our scheme enables nanoscale-thin film technology to be used for all-optical switching of long wavelength light.

© 2010 OSA

1. Introduction

Nonlinearities in optics have been of considerable interest for both science and engineering, for instance in quantum-to-classical transition and in all-optical switching or optical computing [1

K. Jacobs and A. J. Landahl, “Engineering giant nonlinearities in quantum nanosystems,” Phys. Rev. Lett. 103(6), 067201 (2009). [CrossRef] [PubMed]

,2

X. Hu, P. Jiang, C. Ding, H. Yang, and Q. Gong, “Picosecond and low-power all-optical switching based on an organic photonic-bandgap microcavity,” Nat. Photonics 2(3), 185–189 (2008). [CrossRef]

]. In most nonlinear materials, the complex index of refraction can be written as n^=n+iα/2 k0 ( k0 = vacuum wave vector) where n and αare, respectively, the real part of the refractive index and the absorption coefficient, both of which experience pump-induced nonlinear changes [3

R. Lopez, R. F. Haglund, L. C. Feldman, L. A. Boatner, and T. E. Haynes, “Optical nonlinearities in VO[sub 2] nanoparticles and thin films,” Appl. Phys. Lett. 85(22), 5191–5193 (2004). [CrossRef]

–5

N. I. Zheludev, “Nonlinear optics on the nanoscale,” Contemp. Phys. 43(5), 365–377 (2002). [CrossRef]

]. Thin layers of semiconductors and strongly correlated electron systems have been powerful candidates for all-optical switching devices at long wavelength regime, due to their excellent optical properties such as fast carrier dynamics and pump-induced large nonlinearity.

For the thin film, however, despite the large nonlinearity, corresponding nonlinear response ΔT/T (the ratio between the differential transmission and the transmission through the film) is too small, limiting potential photonic applications because nearly constructive multiple interference in the thin film tends to push the transmittance towards unity [6

M. Born, and E. Wolf, Principles of Optics (Cambridge University Press, Cambridge UK, 1999).

] even when the thin film dielectric constants are large. In other words, the product of the pump-induced change of the absorption coefficient Δα and the film thickness or nonlinear interaction length L is much less than one [4

K. F. MacDonald, V. A. Fedotov, and N. I. Zheludev, “Optical nonlinearity resulting from a light-induced structural transition in gallium nanoparticles,” Appl. Phys. Lett. 82(7), 1087–1089 (2003). [CrossRef]

,5

N. I. Zheludev, “Nonlinear optics on the nanoscale,” Contemp. Phys. 43(5), 365–377 (2002). [CrossRef]

]. For example, the optical constants of a few μm-thick semiconductor thin films are dramatically changed at terahertz range by optical pumping, but the corresponding transmission or reflection change is just a few percents [7

D. G. Cooke, F. A. Hegmann, E. C. Young, and T. Tiedje, “Electron mobility in dilute GaAs bismide and nitride alloys measured by time-resolved terahertz spectroscopy,” Appl. Phys. Lett. 89(12), 122103 (2006). [CrossRef]

–9

S. Lysenko, A. J. Rua, V. Vikhnin, J. Jimenez, F. Fernandez, and H. Liu, “Light-induced ultrafast phase transitions in VO2 thin film,” Appl. Surf. Sci. 252(15), 5512–5515 (2006). [CrossRef]

]. Consequently, to have a huge transmission change, all the way to the complete extinction case of ΔT/T≈1 induced by optical pumping, one should force the effective nonlinear response ΔαL to be close to one.

In this regards, many attempts were made to overcome the small nonlinear response of thin film. Forming a composite of one material with another, which has different optical characteristics compared with the previous one, is a common approach to induce enhanced nonlinearity in the visible and the near infrared regime [10

G. L. Fischer, R. W. Boyd, R. J. Gehr, S. A. Jenekhe, J. A. Osaheni, J. E. Sipe, and L. A. Weller-Brophy, “Enhanced nonlinear optical response of composite materials,” Phys. Rev. Lett. 74(10), 1871–1874 (1995). [CrossRef] [PubMed]

–12

R. L. Nelson and R. W. Boyd, “Enhanced electro-optic response of layered composite materials,” Appl. Phys. Lett. 74(17), 2417–2419 (1999). [CrossRef]

]. For the longer wavelength regime, one effective way is to fabricate metamaterials on semiconductor substrates. Since the resonance wavelength and also transmission are strongly affected by the refractive index of the substrate [13

J. H. Kang, J.-H. Choe, D. S. Kim, and Q. H. Park, “Substrate effect on aperture resonances in a thin metal film,” Opt. Express 17(18), 15652–15658 (2009). [CrossRef] [PubMed]

], patterning of the rectangular hole arrays on a thin film can enhance performance of the devices at the shape resonance. In particular, a factor of 2~5 improvement, compared with bare film, in nonlinear response was achieved by fabricating metallic antenna structure arrays [14

E. Hendry, M. J. Lockyear, J. G. Rivas, L. Kuipers, and M. Bonn, “Ultrafast optical switching of the THz transmission through metallic subwavelength hole arrays,” Phys. Rev. B 75(23), 235305 (2007). [CrossRef]

–16

W. J. Padilla, A. J. Taylor, C. Highstrete, M. Lee, and R. D. Averitt, “Dynamical electric and magnetic metamaterial response at terahertz frequencies,” Phys. Rev. Lett. 96(10), 107401 (2006). [CrossRef] [PubMed]

]. However, the perfect transmission control of the long wavelength light is essential to fully utilize the excellent optical properties of the thin film, for instance for Fourier optical, spatial and temporal pulse shaping or a terahertz filter [17

W. L. Chan, H.-T. Chen, A. J. Taylor, I. Brener, M. J. Cich, and D. M. Mittleman, “A spatial light modulator for terahertz beams,” Appl. Phys. Lett. 94(21), 213511 (2009). [CrossRef]

–19

W. L. Chan, M. L. Moravec, R. G. Baraniuk, and D. M. Mittleman, “Terahertz imaging with compressed sensing and phase retrieval,” Opt. Lett. 33(9), 974–976 (2008). [CrossRef] [PubMed]

]. In this work, we show that the absolute switching of terahertz electromagnetic wave with optical pump can be achieved by fabricating nanoresonators [20

H. R. Park, Y. M. Park, H. S. Kim, J. S. Kyoung, M. A. Seo, D. J. Park, Y. H. Ahn, K. J. Ahn, and D. S. Kim, “Terahertz nanoresonators: Giant field enhancement and ultrabroadband performance,” Appl. Phys. Lett. 96(12), 121106 (2010). [CrossRef]

] whose width is in nanometer scale, on a vanadium dioxide (VO2) thin film.

2. Experimental results and discussions

Vanadium dioxide (VO2), a strongly-correlated compound, undergoes first-order insulator-to-metal phase transition at critical temperature Tc = 340 K [21

F. J. Morin, “Oxides Which Show a Metal-to-Insulator Transition at the Neel Temperature,” Phys. Rev. Lett. 3(1), 34–36 (1959). [CrossRef]

,22

M. Nakajima, N. Takubo, Z. Hiroi, Y. Ueda, and T. Suemoto, “Photoinduced metallic state in VO2 proved by the terahertz pump-probe spectroscopy,” Appl. Phys. Lett. 92(1), 011907 (2008). [CrossRef]

]. This phase transition is reversible and during this transition, the crystal structure changes from monoclinic at low temperature to rutile at high temperature [Fig. 1(a) ]. The conductivity jumps by several orders of magnitude and optical constants experience large changes through this transition [23

D. J. Hilton, R. P. Prasankumar, S. Fourmaux, A. Cavalleri, D. Brassard, M. A. El Khakani, J. C. Kieffer, A. J. Taylor, and R. D. Averitt, “Enhanced photosusceptibility near Tc for the light-induced insulator-to-metal phase transition in vanadium dioxide,” Phys. Rev. Lett. 99(22), 226401 (2007). [CrossRef]

,24

P. U. Jepsen, B. M. Fischer, A. Thoman, H. Helm, J. Y. Suh, R. Lopez, and R. F. Haglund, “Metal-insulator phase transition in a VO2 thin film observed with terahertz spectroscopy,” Phys. Rev. B 74(20), 205103 (2006). [CrossRef]

], which can also be induced optically or electrically [22

M. Nakajima, N. Takubo, Z. Hiroi, Y. Ueda, and T. Suemoto, “Photoinduced metallic state in VO2 proved by the terahertz pump-probe spectroscopy,” Appl. Phys. Lett. 92(1), 011907 (2008). [CrossRef]

,25

A. Cavalleri, T. Dekorsy, H. H. W. Chong, J. C. Kieffer, and R. W. Schoenlein, “Evidence for a structurally-driven insulator-to-metal transition in VO2: A view from the ultrafast timescale,” Phys. Rev. B 70, 161102 (2004). [CrossRef]

–27

H.-T. Kim, B.-G. Chae, D.-H. Youn, S.-L. Maeng, G. Kim, K.-Y. Kang, and Y.-S. Lim, “Mechanism and observation of Mott transition in VO2-based two- and three-terminal devices,” N. J. Phys. 6, 52 (2004). [CrossRef]

]. Our 100-nm-thick VO2 thin films were grown on 430-μm-thick C-plane Al2O3 substrates by radio-frequency magnetron sputtering method whereas the sol-gel method is used to grow 25-nm-thick VO2 thin films on the same substrate [28

Y. Shin, J. Moon, H. Ju, and C. Park, “Growth and electrical properties of vanadium-dioxide thin films fabricated by magnetron sputtering,” J. Korean Phys. Soc. 52(6), 1828–1831 (2008). [CrossRef]

–30

B. G. Chae, H. T. Kim, and S. J. Yun, “Characteristics of W- and Ti-Doped VO2 Thin Films Prepared by Sol-Gel Method,” Electrochem. Solid State 11(6), D53–D55 (2008). [CrossRef]

].

Fig. 1 (a) Schematic description of the two crystal structures of VO2: the insulator (monoclinic) phase below the critical temperature Tc = 340 K and the metal (rutile) phase above Tc. Only vanadium atoms are visualized in the figure and each atom is surrounded by an oxygen octahedron. (b) The temperature-dependent hysteresis of the THz transmittance through an un-patterned 100-nm-thick VO2 thin film at 0.4 THz (raising (lowering) temperature: filled (empty) circle). Hysteresis curve shows that the critical temperature Tc of our sample is about 345 K.

Terahertz time-domain spectroscopy (THz - TDS) is a powerful tool to detect the insulator-to-metal phase transition in VO2 since THz wave is quite sensitive to the free carrier response [31

P. A. George, J. Strait, J. Dawlaty, S. Shivaraman, M. Chandrashekhar, F. Rana, and M. G. Spencer, “Ultrafast optical-pump terahertz-probe spectroscopy of the carrier relaxation and recombination dynamics in epitaxial graphene,” Nano Lett. 8(12), 4248–4251 (2008). [CrossRef]

–33

G. Segschneider, F. Jacob, T. Löffler, H. G. Roskos, S. Tautz, P. Kiesel, and G. Döhler, “Free-carrier dynamics in low-temperature-grown GaAs at high excitation densities investigated by time-domain terahertz spectroscopy,” Phys. Rev. B 65(12), 125205 (2002). [CrossRef]

]. Our THz - TDS system has a spectral range from 0.1 to 2.0 THz. The output of a 130 fs Ti:sapphire mode-locked laser (coherent Mira) and a semi-insulating GaAs emitter biased with 50 kHz and 150 V square voltage pulses are employed to generate a single-cycle THz pulse. Electro-optic detection method is chosen to measure the transmitted time-domain signals. After Fourier transforming time traces, we obtain transmitted amplitude and phase information [34

D. Grischkowsky, S. Keiding, M. Vanexter, and C. Fattinger, “Far-Infrared Time-Domain Spectroscopy with Terahertz Beams of Dielectrics and Semiconductors,” J. Opt. Soc. Am. B 7(10), 2006–2015 (1990). [CrossRef]

–37

G. Gallot and D. Grischkowsky, “Electro-optic detection of terahertz radiation,” J. Opt. Soc. Am. B 16(8), 1204–1212 (1999). [CrossRef]

]. We firstly measure the THz transmittance of our bare VO2 thin films as a function of temperature [Fig. 1(b)]. We attach our sample on a reference aperture of 1 mm by 1 mm [38

M. A. Seo, H. R. Park, S. M. Koo, D. J. Park, J. H. Kang, O. K. Suwal, S. S. Choi, P. C. M. Planken, G. S. Park, N. K. Park, Q. H. Park, and D. S. Kim, “Terahertz field enhancement by a metallic nano slit operating beyond the skin-depth limit,” Nat. Photonics 3(3), 152–156 (2009). [CrossRef]

] and control the temperature using a heater. The temperature of the sample is monitored by reading the resistivity of thermistors (SEMITEC 104JT-015). Transmittance at T = 310 K is used as a reference. Figure 1 (b) shows a typical hysteresis curve of the normalized transmittance (filled (empty) circles for temperature up (down)) at a selected frequency, 0.4 THz, which exhibits the critical temperature Tc at 345 K. In metallic state, the complex index of refraction is deduced from the transmitted THz wave to be about 85+86i at 0.4 THz, in good agreement with earlier works [23

D. J. Hilton, R. P. Prasankumar, S. Fourmaux, A. Cavalleri, D. Brassard, M. A. El Khakani, J. C. Kieffer, A. J. Taylor, and R. D. Averitt, “Enhanced photosusceptibility near Tc for the light-induced insulator-to-metal phase transition in vanadium dioxide,” Phys. Rev. Lett. 99(22), 226401 (2007). [CrossRef]

,24

P. U. Jepsen, B. M. Fischer, A. Thoman, H. Helm, J. Y. Suh, R. Lopez, and R. F. Haglund, “Metal-insulator phase transition in a VO2 thin film observed with terahertz spectroscopy,” Phys. Rev. B 74(20), 205103 (2006). [CrossRef]

].

To enhance the optical nonlinearity, we pattern the μm- and nm-width resonators, forming periodic array of slot antennas, using electron beam lithography [20

H. R. Park, Y. M. Park, H. S. Kim, J. S. Kyoung, M. A. Seo, D. J. Park, Y. H. Ahn, K. J. Ahn, and D. S. Kim, “Terahertz nanoresonators: Giant field enhancement and ultrabroadband performance,” Appl. Phys. Lett. 96(12), 121106 (2010). [CrossRef]

] on a 100-nm-thick gold layer deposited on VO2/Al2O3 [39

M. Seo, J. Kyoung, H. Park, S. Koo, H. S. Kim, H. Bernien, B. J. Kim, J. H. Choe, Y. H. Ahn, H.-T. Kim, N. Park, Q. H. Park, K. Ahn, and D. S. Kim, “Active terahertz nanoantennas based on VO2 phase transition,” Nano Lett. 10(6), 2064–2068 (2010). [CrossRef] [PubMed]

]. Figure 2 (a) shows a scanning electron microscopy (SEM) image of our sample patterned with 350-nm-width nanoresonators. The length of each resonator is fixed at L = 150 μm. The horizontal period of the rectangle hole array is 100-μm and the vertical period 180-μm. The 27-μm-width sample has the same periodicities. In order to induce optical nonlinearity, we excite our samples using 2.33 eV continuous wave laser (532 nm wavelength) focused onto a 1.5 millimeter spot size covering the whole pattern area [Fig. 2(b)] and measure the THz transmission while raising the optical pumping power. The incident THz polarization is along the short side of the resonators.

Fig. 2 (a) Scanning electron microscopy (SEM) image of our sample patterned with 350-nm-width resonators on 100-nm-thick VO2 film using electron beam lithography. The thickness of the gold layer is 100 nm and the horizontal period of the rectangle hole array is 100 μm and the vertical 130 μm. (b) Schematic of our photo excitation experiments. Single cycle THz pulse impinges on the gold surface first and passes through the VO2 side. The pump laser at 532 nm wavelength, illuminates the back side of the sample and induces phase transition of the VO2 thin film. (c) Time traces for bare (top) and nanoresonator patterned (bottom) samples with zero (blue lines) and 500 mW (red lines) absorbed pumping power. For the bare film, the difference between the signals with and without pumping is hardly recognizable while quasi-periodic feature, due to the fundamental half wavelength resonance, completely disappears with the same pumping power for the nanoresonator patterned sample. (d) Fast Fourier transform of the measured THz pulse for 350-nm-width rectangle hole array patterned sample exhibit strong resonance characteristic at the zero pumping power. The transmission at the resonance frequency is completely extinct when the pumping power reaches 550 mW.

Figure 2(c) compares time-domain transmission signals for the un-patterned (top) and the nano-patterned (bottom; w = 350 nm) sample with (red line) and without (blue line) pump. For the un-patterned sample, the two terahertz pulses can be hardly distinguishable, indicating no significant transmission change up to 500 mW of absorbed pumping power. The absorbed power is deduced from the incident power subtracted with the reflected and transmitted power (A = 1-R-T) for bare and patterned samples, respectively. In stark contrast to the bare film case, for the nano-patterned sample, the transmitted signal, which displays quasi-periodic feature due to the fundamental half wavelength resonance [40

J. W. Lee, M. A. Seo, D. J. Park, S. C. Jeoung, Q. H. Park, Ch. Lienau, and D. S. Kim, “Terahertz transparency at Fabry-Perot resonances of periodic slit arrays in a metal plate: experiment and theory,” Opt. Express 14(26), 12637–12643 (2006). [CrossRef] [PubMed]

,41

J. W. Lee, M. A. Seo, J. Y. Sohn, Y. H. Ahn, D. S. Kim, S. C. Jeoung, Ch. Lienau, and Q. H. Park, “Invisible plasmonic meta-materials through impedance matching to vacuum,” Opt. Express 13(26), 10681–10687 (2005). [CrossRef] [PubMed]

], completely disappears with the same pumping power. Transmission spectra shown in Fig. 2(d), obtained from fast Fourier transforming time-domain signals with increasing pump power, display the strong resonant feature being turned-off until no transmission remains. Resonance frequency 0.375 THz is dictated by the antenna length and VO2 index of refraction at the insulating phase [13

J. H. Kang, J.-H. Choe, D. S. Kim, and Q. H. Park, “Substrate effect on aperture resonances in a thin metal film,” Opt. Express 17(18), 15652–15658 (2009). [CrossRef] [PubMed]

,42

D. J. Park, S. B. Choi, Y. H. Ahn, F. Rotermund, I. B. Sohn, C. Kang, M. S. Jeong, and D. S. Kim, “Terahertz near-field enhancement in narrow rectangular apertures on metal film,” Opt. Express 17(15), 12493–12501 (2009). [CrossRef] [PubMed]

–44

F. J. García-Vidal, E. Moreno, J. A. Porto, and L. Martín-Moreno, “Transmission of light through a single rectangular hole,” Phys. Rev. Lett. 95(10), 103901 (2005). [CrossRef] [PubMed]

]. Since the horizontal period of our rectangular hole arrays is subwavelength, the spectrum does not include any Rayleigh minima [45

J. W. Lee, M. A. Seo, D. H. Kang, K. S. Khim, S. C. Jeoung, and D. S. Kim, “Terahertz electromagnetic wave transmission through random arrays of single rectangular holes and slits in thin metallic sheets,” Phys. Rev. Lett. 99(13), 137401 (2007). [CrossRef] [PubMed]

,46

D. J. Park, S. B. Choi, Y. H. Ahn, Q. H. Park, and D. S. Kim, “Theoretical Study of Terahertz Near-Field Enhancement Assisted by Shape Resonance in Rectangular Hole Arrays in Metal Films,” J. Korean Phys. Soc. 54(1), 64–70 (2009). [CrossRef]

].

Displayed in Fig. 3(a) are differential transmissions at 0.375 THz for bare (filled gray triangle), w = 27 μm (filled blue square) and w = 350 nm (filled red circle) patterned samples, as a function of the excitation power. While only 50% change in transmission is seen for the bare sample at the maximum pumping power, over 99.99% extinction is clearly visible for the w = 350 nm sample. Comparing the differential transmission of μm-size sample with that of nm-size one shows that nano-patterned case gives rise to much more drastic extinction with increasing photo-excitation power. Meanwhile, differential transmission as a function of pump power becomes more gradual as the slot width decreases.

Fig. 3 (a) The differential transmission signals of a bare VO2 film (filled gray triangle), 27 μm (filled blue square) and 350 nm (filled red circle) width antenna arrays on VO2 films at the resonance frequency (0.375 THz) as a function of the pumping power. Only small changes in transmission are seen for the bare sample, while perfect extinction is clearly visible for the 350-nm-width resonators patterned sample above 450 mW of absorbed power. (b) Nonlinear response of the bare and nanoresonator patterned sample. Nonlinear response suddenly increases at some critical pumping power, 300 mW, as the VO2 thin film undergoes insulator-to-metal phase transition.

Figure 3(b) shows the changes of effective nonlinear responses ( ΔαL) at 0.375 THz due to optical pump for unpatterned (filled gray triangle) and nano-patterned (filled red circle) samples, respectively. The absorption coefficients of the bare film are estimated from the amplitude and phase information of the transmitted terahertz wave [34

D. Grischkowsky, S. Keiding, M. Vanexter, and C. Fattinger, “Far-Infrared Time-Domain Spectroscopy with Terahertz Beams of Dielectrics and Semiconductors,” J. Opt. Soc. Am. B 7(10), 2006–2015 (1990). [CrossRef]

,47

N. Laman and D. Grischkowsky, “Terahertz conductivity of thin metal films,” Appl. Phys. Lett. 93(5), 051105 (2008). [CrossRef]

,48

T. I. Jeon, J. H. Son, K. H. An, Y. H. Lee, and Y. S. Lee, “Terahertz absorption and dispersion of fluorine-doped single-walled carbon nanotube,” J. Appl. Phys. 98(3), 034316 (2005). [CrossRef]

]. We use the same method with the patterned sample regarding the patterned gold layer together with VO2 thin film as a homogeneous material. For the bare film, the nonlinear responses are always less than 0.2 explaining the small terahertz transmission modulation. However, the effective nonlinear response of the nano-patterned sample is hugely enhanced and exhibits quite different feature compared with the un-patterned case. Nonlinear response of the nano-patterned sample is always larger than that of the un-patterned one but it suddenly increases at some critical pumping power, 350 mW, indicating optical pump-induced insulator-to-metal phase transition, and finally reaches the value of 0.7.

Further reducing the thickness of the VO2 thin film from 100 nm to 25 nm gives even more dramatic results when comparing the patterned and un-patterned samples. Figure 4 shows the differential transmissions for the 25-nm-thick bare VO2 film (filled gray triangle) and 200-nm-width slot antenna patterned sample (filled red circle), measured at 0.42 THz, respectively. We can hardly see any change due to optical pumping for the un-patterned sample while near perfect switching performance is observed with the patterned sample. Clearly, this result shows that our novel strategy, nano-size patterning, to enhance the optical nonlinear response, can also be applicable to the ultra thin film corresponding to ~λ/30,000.

Fig. 4 The differential transmissions for the 25-nm-thick bare VO2 film (filled gray triangle) and 200-nm-width slot antenna patterned sample (filled red circle) are measured at 0.42 THz. For the bare film, no changes are seen due to optical pumping while near perfect switching performance is observed with the patterned sample.

To better understand the physical origin of enhanced nonlinear response, we have carried out finite-difference time-domain (FDTD) method modeling using asymptotically varying grid sizes [49

A. Taflove, and S. C. Hagness, Computational Electromagnetics: The Finite-Difference Time-Domain Method (Artech House, Boston, 2000).

]. We use n^=3 for insulating state of VO2 and 10.24+10.10 i for metal state. The incident wave comes from the left side. Figure 5(a) and 5(b) show the time-averaged electric-field intensity for λ = 34.48 μm in the presence of patterned VO2 film without and with optical pumping, respectively. Simulation results explain how our nano-patterned sample can enhance the nonlinear response. A single nanoresonator located at the center has 100-nm-width and 10-μm-length with λ = 34.48 μm as the fundamental resonance wavelength. Since the rectangular hole strongly attracts surrounding electromagnetic waves and funnels them (Fig. 5(a)), electric field inside the hole is hugely enhanced, and such field enhancement keeps increasing with decreasing rectangle width at the resonance [38

M. A. Seo, H. R. Park, S. M. Koo, D. J. Park, J. H. Kang, O. K. Suwal, S. S. Choi, P. C. M. Planken, G. S. Park, N. K. Park, Q. H. Park, and D. S. Kim, “Terahertz field enhancement by a metallic nano slit operating beyond the skin-depth limit,” Nat. Photonics 3(3), 152–156 (2009). [CrossRef]

,43

M. A. Seo, A. J. L. Adam, J. H. Kang, J. W. Lee, K. J. Ahn, Q. H. Park, P. C. M. Planken, and D. S. Kim, “Near field imaging of terahertz focusing onto rectangular apertures,” Opt. Express 16(25), 20484–20489 (2008). [CrossRef] [PubMed]

,44

F. J. García-Vidal, E. Moreno, J. A. Porto, and L. Martín-Moreno, “Transmission of light through a single rectangular hole,” Phys. Rev. Lett. 95(10), 103901 (2005). [CrossRef] [PubMed]

]. Electrostatic energy stored in tiny volume of the narrow slots results in enhanced far-field transmission for the insulating VO2 [38

M. A. Seo, H. R. Park, S. M. Koo, D. J. Park, J. H. Kang, O. K. Suwal, S. S. Choi, P. C. M. Planken, G. S. Park, N. K. Park, Q. H. Park, and D. S. Kim, “Terahertz field enhancement by a metallic nano slit operating beyond the skin-depth limit,” Nat. Photonics 3(3), 152–156 (2009). [CrossRef]

,42

D. J. Park, S. B. Choi, Y. H. Ahn, F. Rotermund, I. B. Sohn, C. Kang, M. S. Jeong, and D. S. Kim, “Terahertz near-field enhancement in narrow rectangular apertures on metal film,” Opt. Express 17(15), 12493–12501 (2009). [CrossRef] [PubMed]

]. In stark contrast, when the underlying film becomes metallic, it effectively shuts off the resonator and eliminates funneling effect resulting colossal transmission extinction (Fig. 5(b)). These FDTD simulations well explain the role of nanoresonators for enhanced nonlinear response at least qualitatively

Fig. 5 Averaged horizontal electric field for λ = 34.48 μm calculated by finite difference time domain (FDTD) method to investigate the physical origin of enhanced nonlinear response of nanoresonators. The incident wave comes from the left to the right. (a) patterned sample with insulating state of VO2 (b) patterned sample with metal state of VO2. For the patterned film case, nanoresonators attract surrounding waves and funnel them to the other side making enhanced transmission at the insulating state of VO2 while most of the beam reflects back at the surface when the VO2 film is in the metallic state.

3. Conclusion

In conclusion, we have demonstrated that VO2 thin film with nm-width rectangular apertures comprises a new class of metamaterial achieving orders of magnitudes improvement in extinction with modest photo-excitation power, overcoming multiple-interference in thin-films. Strongly localized near field in the resonators induces the enhanced far-field transmission for the insulating VO2 while the resonators are completely inoperative when the underlying VO2 film becomes fully metallic, making perfect transmission control possible. Corresponding giant enhanced nonlinear response ΔαLreaches 0.7 with 350-nm-width patterned sample, despite ultrathin film thickness. Room temperature carrier lifetime of the order of picosecond for VO2 [22

M. Nakajima, N. Takubo, Z. Hiroi, Y. Ueda, and T. Suemoto, “Photoinduced metallic state in VO2 proved by the terahertz pump-probe spectroscopy,” Appl. Phys. Lett. 92(1), 011907 (2008). [CrossRef]

,23

D. J. Hilton, R. P. Prasankumar, S. Fourmaux, A. Cavalleri, D. Brassard, M. A. El Khakani, J. C. Kieffer, A. J. Taylor, and R. D. Averitt, “Enhanced photosusceptibility near Tc for the light-induced insulator-to-metal phase transition in vanadium dioxide,” Phys. Rev. Lett. 99(22), 226401 (2007). [CrossRef]

] strongly suggests the potential use of nano-patterned VO2 thin films for all-optical switching having huge dynamic range. Our new scheme bridges the gap between thin film technology, nanotechnology and active metamaterials research.

Acknowledgments

The authors gratefully acknowledge the assistance of Prof. R. Huber and Dr. R. Lopez for nice discussion and the SEMITEC, Innochips Technology and Tnest in offering excellent thermistors. This research was supported by the Korea Science and Engineering Foundation (KOSEF) (SRC, No:R11-2008-095-01000-0) and the Korea Research Foundation (KRF) grant funded by the Korea government (MEST) (No:2009-0071309), KICOS (GRL, K20815000003), Seoul Science Fellowship and the Seoul R&BD Program(10543).

References and links

1.

K. Jacobs and A. J. Landahl, “Engineering giant nonlinearities in quantum nanosystems,” Phys. Rev. Lett. 103(6), 067201 (2009). [CrossRef] [PubMed]

2.

X. Hu, P. Jiang, C. Ding, H. Yang, and Q. Gong, “Picosecond and low-power all-optical switching based on an organic photonic-bandgap microcavity,” Nat. Photonics 2(3), 185–189 (2008). [CrossRef]

3.

R. Lopez, R. F. Haglund, L. C. Feldman, L. A. Boatner, and T. E. Haynes, “Optical nonlinearities in VO[sub 2] nanoparticles and thin films,” Appl. Phys. Lett. 85(22), 5191–5193 (2004). [CrossRef]

4.

K. F. MacDonald, V. A. Fedotov, and N. I. Zheludev, “Optical nonlinearity resulting from a light-induced structural transition in gallium nanoparticles,” Appl. Phys. Lett. 82(7), 1087–1089 (2003). [CrossRef]

5.

N. I. Zheludev, “Nonlinear optics on the nanoscale,” Contemp. Phys. 43(5), 365–377 (2002). [CrossRef]

6.

M. Born, and E. Wolf, Principles of Optics (Cambridge University Press, Cambridge UK, 1999).

7.

D. G. Cooke, F. A. Hegmann, E. C. Young, and T. Tiedje, “Electron mobility in dilute GaAs bismide and nitride alloys measured by time-resolved terahertz spectroscopy,” Appl. Phys. Lett. 89(12), 122103 (2006). [CrossRef]

8.

A. Leitenstorfer, S. Hunsche, J. Shah, M. C. Nuss, and W. H. Knox, “Femtosecond Charge Transport in Polar Semiconductors,” Phys. Rev. Lett. 82(25), 5140–5143 (1999). [CrossRef]

9.

S. Lysenko, A. J. Rua, V. Vikhnin, J. Jimenez, F. Fernandez, and H. Liu, “Light-induced ultrafast phase transitions in VO2 thin film,” Appl. Surf. Sci. 252(15), 5512–5515 (2006). [CrossRef]

10.

G. L. Fischer, R. W. Boyd, R. J. Gehr, S. A. Jenekhe, J. A. Osaheni, J. E. Sipe, and L. A. Weller-Brophy, “Enhanced nonlinear optical response of composite materials,” Phys. Rev. Lett. 74(10), 1871–1874 (1995). [CrossRef] [PubMed]

11.

N. N. Lepeshkin, A. Schweinsberg, G. Piredda, R. S. Bennink, and R. W. Boyd, “Enhanced nonlinear optical response of one-dimensional metal-dielectric photonic crystals,” Phys. Rev. Lett. 93(12), 123902 (2004). [CrossRef] [PubMed]

12.

R. L. Nelson and R. W. Boyd, “Enhanced electro-optic response of layered composite materials,” Appl. Phys. Lett. 74(17), 2417–2419 (1999). [CrossRef]

13.

J. H. Kang, J.-H. Choe, D. S. Kim, and Q. H. Park, “Substrate effect on aperture resonances in a thin metal film,” Opt. Express 17(18), 15652–15658 (2009). [CrossRef] [PubMed]

14.

E. Hendry, M. J. Lockyear, J. G. Rivas, L. Kuipers, and M. Bonn, “Ultrafast optical switching of the THz transmission through metallic subwavelength hole arrays,” Phys. Rev. B 75(23), 235305 (2007). [CrossRef]

15.

H.-T. Chen, W. J. Padilla, J. M. O. Zide, S. R. Bank, A. C. Gossard, A. J. Taylor, and R. D. Averitt, “Ultrafast optical switching of terahertz metamaterials fabricated on ErAs/GaAs nanoisland superlattices,” Opt. Lett. 32(12), 1620–1622 (2007). [CrossRef] [PubMed]

16.

W. J. Padilla, A. J. Taylor, C. Highstrete, M. Lee, and R. D. Averitt, “Dynamical electric and magnetic metamaterial response at terahertz frequencies,” Phys. Rev. Lett. 96(10), 107401 (2006). [CrossRef] [PubMed]

17.

W. L. Chan, H.-T. Chen, A. J. Taylor, I. Brener, M. J. Cich, and D. M. Mittleman, “A spatial light modulator for terahertz beams,” Appl. Phys. Lett. 94(21), 213511 (2009). [CrossRef]

18.

I. H. Libon, S. Baumgartner, M. Hempel, N. E. Hecker, J. Feldmann, M. Koch, and P. Dawson, “An optically controllable terahertz filter,” Appl. Phys. Lett. 76(20), 2821–2823 (2000). [CrossRef]

19.

W. L. Chan, M. L. Moravec, R. G. Baraniuk, and D. M. Mittleman, “Terahertz imaging with compressed sensing and phase retrieval,” Opt. Lett. 33(9), 974–976 (2008). [CrossRef] [PubMed]

20.

H. R. Park, Y. M. Park, H. S. Kim, J. S. Kyoung, M. A. Seo, D. J. Park, Y. H. Ahn, K. J. Ahn, and D. S. Kim, “Terahertz nanoresonators: Giant field enhancement and ultrabroadband performance,” Appl. Phys. Lett. 96(12), 121106 (2010). [CrossRef]

21.

F. J. Morin, “Oxides Which Show a Metal-to-Insulator Transition at the Neel Temperature,” Phys. Rev. Lett. 3(1), 34–36 (1959). [CrossRef]

22.

M. Nakajima, N. Takubo, Z. Hiroi, Y. Ueda, and T. Suemoto, “Photoinduced metallic state in VO2 proved by the terahertz pump-probe spectroscopy,” Appl. Phys. Lett. 92(1), 011907 (2008). [CrossRef]

23.

D. J. Hilton, R. P. Prasankumar, S. Fourmaux, A. Cavalleri, D. Brassard, M. A. El Khakani, J. C. Kieffer, A. J. Taylor, and R. D. Averitt, “Enhanced photosusceptibility near Tc for the light-induced insulator-to-metal phase transition in vanadium dioxide,” Phys. Rev. Lett. 99(22), 226401 (2007). [CrossRef]

24.

P. U. Jepsen, B. M. Fischer, A. Thoman, H. Helm, J. Y. Suh, R. Lopez, and R. F. Haglund, “Metal-insulator phase transition in a VO2 thin film observed with terahertz spectroscopy,” Phys. Rev. B 74(20), 205103 (2006). [CrossRef]

25.

A. Cavalleri, T. Dekorsy, H. H. W. Chong, J. C. Kieffer, and R. W. Schoenlein, “Evidence for a structurally-driven insulator-to-metal transition in VO2: A view from the ultrafast timescale,” Phys. Rev. B 70, 161102 (2004). [CrossRef]

26.

A. Cavalleri, C. Tóth, C. W. Siders, J. A. Squier, F. Ráksi, P. Forget, and J. C. Kieffer, “Femtosecond Structural Dynamics in VO2 during an Ultrafast Solid-Solid Phase Transition,” Phys. Rev. Lett. 87(23), 237401 (2001). [CrossRef] [PubMed]

27.

H.-T. Kim, B.-G. Chae, D.-H. Youn, S.-L. Maeng, G. Kim, K.-Y. Kang, and Y.-S. Lim, “Mechanism and observation of Mott transition in VO2-based two- and three-terminal devices,” N. J. Phys. 6, 52 (2004). [CrossRef]

28.

Y. Shin, J. Moon, H. Ju, and C. Park, “Growth and electrical properties of vanadium-dioxide thin films fabricated by magnetron sputtering,” J. Korean Phys. Soc. 52(6), 1828–1831 (2008). [CrossRef]

29.

S. J. Yun, J. W. Lim, B.-G. Chae, B. J. Kim, and H.-T. Kim, “Characteristics of vanadium dioxide films deposited by RF-magnetron sputter deposition technique using V-metal target,” Physica B 403, 1381–1383 (2008).

30.

B. G. Chae, H. T. Kim, and S. J. Yun, “Characteristics of W- and Ti-Doped VO2 Thin Films Prepared by Sol-Gel Method,” Electrochem. Solid State 11(6), D53–D55 (2008). [CrossRef]

31.

P. A. George, J. Strait, J. Dawlaty, S. Shivaraman, M. Chandrashekhar, F. Rana, and M. G. Spencer, “Ultrafast optical-pump terahertz-probe spectroscopy of the carrier relaxation and recombination dynamics in epitaxial graphene,” Nano Lett. 8(12), 4248–4251 (2008). [CrossRef]

32.

R. Huber, F. Tauser, A. Brodschelm, M. Bichler, G. Abstreiter, and A. Leitenstorfer, “How many-particle interactions develop after ultrafast excitation of an electron-hole plasma,” Nature 414(6861), 286–289 (2001). [CrossRef] [PubMed]

33.

G. Segschneider, F. Jacob, T. Löffler, H. G. Roskos, S. Tautz, P. Kiesel, and G. Döhler, “Free-carrier dynamics in low-temperature-grown GaAs at high excitation densities investigated by time-domain terahertz spectroscopy,” Phys. Rev. B 65(12), 125205 (2002). [CrossRef]

34.

D. Grischkowsky, S. Keiding, M. Vanexter, and C. Fattinger, “Far-Infrared Time-Domain Spectroscopy with Terahertz Beams of Dielectrics and Semiconductors,” J. Opt. Soc. Am. B 7(10), 2006–2015 (1990). [CrossRef]

35.

Z. Jiang, M. Li, and X. C. Zhang, “Dielectric constant measurement of thin films by differential time-domain spectroscopy,” Appl. Phys. Lett. 76(22), 3221–3223 (2000). [CrossRef]

36.

J. Lee, M. Seo, D. Park, D. Kim, S. Jeoung, Ch. Lienau, Q. H. Park, and P. Planken, “Shape resonance omni-directional terahertz filters with near-unity transmittance,” Opt. Express 14(3), 1253–1259 (2006). [CrossRef] [PubMed]

37.

G. Gallot and D. Grischkowsky, “Electro-optic detection of terahertz radiation,” J. Opt. Soc. Am. B 16(8), 1204–1212 (1999). [CrossRef]

38.

M. A. Seo, H. R. Park, S. M. Koo, D. J. Park, J. H. Kang, O. K. Suwal, S. S. Choi, P. C. M. Planken, G. S. Park, N. K. Park, Q. H. Park, and D. S. Kim, “Terahertz field enhancement by a metallic nano slit operating beyond the skin-depth limit,” Nat. Photonics 3(3), 152–156 (2009). [CrossRef]

39.

M. Seo, J. Kyoung, H. Park, S. Koo, H. S. Kim, H. Bernien, B. J. Kim, J. H. Choe, Y. H. Ahn, H.-T. Kim, N. Park, Q. H. Park, K. Ahn, and D. S. Kim, “Active terahertz nanoantennas based on VO2 phase transition,” Nano Lett. 10(6), 2064–2068 (2010). [CrossRef] [PubMed]

40.

J. W. Lee, M. A. Seo, D. J. Park, S. C. Jeoung, Q. H. Park, Ch. Lienau, and D. S. Kim, “Terahertz transparency at Fabry-Perot resonances of periodic slit arrays in a metal plate: experiment and theory,” Opt. Express 14(26), 12637–12643 (2006). [CrossRef] [PubMed]

41.

J. W. Lee, M. A. Seo, J. Y. Sohn, Y. H. Ahn, D. S. Kim, S. C. Jeoung, Ch. Lienau, and Q. H. Park, “Invisible plasmonic meta-materials through impedance matching to vacuum,” Opt. Express 13(26), 10681–10687 (2005). [CrossRef] [PubMed]

42.

D. J. Park, S. B. Choi, Y. H. Ahn, F. Rotermund, I. B. Sohn, C. Kang, M. S. Jeong, and D. S. Kim, “Terahertz near-field enhancement in narrow rectangular apertures on metal film,” Opt. Express 17(15), 12493–12501 (2009). [CrossRef] [PubMed]

43.

M. A. Seo, A. J. L. Adam, J. H. Kang, J. W. Lee, K. J. Ahn, Q. H. Park, P. C. M. Planken, and D. S. Kim, “Near field imaging of terahertz focusing onto rectangular apertures,” Opt. Express 16(25), 20484–20489 (2008). [CrossRef] [PubMed]

44.

F. J. García-Vidal, E. Moreno, J. A. Porto, and L. Martín-Moreno, “Transmission of light through a single rectangular hole,” Phys. Rev. Lett. 95(10), 103901 (2005). [CrossRef] [PubMed]

45.

J. W. Lee, M. A. Seo, D. H. Kang, K. S. Khim, S. C. Jeoung, and D. S. Kim, “Terahertz electromagnetic wave transmission through random arrays of single rectangular holes and slits in thin metallic sheets,” Phys. Rev. Lett. 99(13), 137401 (2007). [CrossRef] [PubMed]

46.

D. J. Park, S. B. Choi, Y. H. Ahn, Q. H. Park, and D. S. Kim, “Theoretical Study of Terahertz Near-Field Enhancement Assisted by Shape Resonance in Rectangular Hole Arrays in Metal Films,” J. Korean Phys. Soc. 54(1), 64–70 (2009). [CrossRef]

47.

N. Laman and D. Grischkowsky, “Terahertz conductivity of thin metal films,” Appl. Phys. Lett. 93(5), 051105 (2008). [CrossRef]

48.

T. I. Jeon, J. H. Son, K. H. An, Y. H. Lee, and Y. S. Lee, “Terahertz absorption and dispersion of fluorine-doped single-walled carbon nanotube,” J. Appl. Phys. 98(3), 034316 (2005). [CrossRef]

49.

A. Taflove, and S. C. Hagness, Computational Electromagnetics: The Finite-Difference Time-Domain Method (Artech House, Boston, 2000).

OCIS Codes
(050.1220) Diffraction and gratings : Apertures
(190.0190) Nonlinear optics : Nonlinear optics
(260.5740) Physical optics : Resonance

ToC Category:
Nonlinear Optics

History
Original Manuscript: May 11, 2010
Revised Manuscript: July 1, 2010
Manuscript Accepted: July 2, 2010
Published: July 21, 2010

Citation
Jisoo Kyoung, Minah Seo, Hyeongryeol Park, Sukmo Koo, Hyun-sun Kim, Youngmi Park, Bong-Jun Kim, Kwangjun Ahn, Namkyoo Park, Hyun-Tak Kim, and Dai-Sik Kim, "Giant nonlinear response of terahertz nanoresonators on VO2 thin film," Opt. Express 18, 16452-16459 (2010)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-18-16-16452


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References

  1. K. Jacobs and A. J. Landahl, “Engineering giant nonlinearities in quantum nanosystems,” Phys. Rev. Lett. 103(6), 067201 (2009). [CrossRef] [PubMed]
  2. X. Hu, P. Jiang, C. Ding, H. Yang, and Q. Gong, “Picosecond and low-power all-optical switching based on an organic photonic-bandgap microcavity,” Nat. Photonics 2(3), 185–189 (2008). [CrossRef]
  3. R. Lopez, R. F. Haglund, L. C. Feldman, L. A. Boatner, and T. E. Haynes, “Optical nonlinearities in VO[sub 2] nanoparticles and thin films,” Appl. Phys. Lett. 85(22), 5191–5193 (2004). [CrossRef]
  4. K. F. MacDonald, V. A. Fedotov, and N. I. Zheludev, “Optical nonlinearity resulting from a light-induced structural transition in gallium nanoparticles,” Appl. Phys. Lett. 82(7), 1087–1089 (2003). [CrossRef]
  5. N. I. Zheludev, “Nonlinear optics on the nanoscale,” Contemp. Phys. 43(5), 365–377 (2002). [CrossRef]
  6. M. Born, and E. Wolf, Principles of Optics (Cambridge University Press, Cambridge UK, 1999).
  7. D. G. Cooke, F. A. Hegmann, E. C. Young, and T. Tiedje, “Electron mobility in dilute GaAs bismide and nitride alloys measured by time-resolved terahertz spectroscopy,” Appl. Phys. Lett. 89(12), 122103 (2006). [CrossRef]
  8. A. Leitenstorfer, S. Hunsche, J. Shah, M. C. Nuss, and W. H. Knox, “Femtosecond Charge Transport in Polar Semiconductors,” Phys. Rev. Lett. 82(25), 5140–5143 (1999). [CrossRef]
  9. S. Lysenko, A. J. Rua, V. Vikhnin, J. Jimenez, F. Fernandez, and H. Liu, “Light-induced ultrafast phase transitions in VO2 thin film,” Appl. Surf. Sci. 252(15), 5512–5515 (2006). [CrossRef]
  10. G. L. Fischer, R. W. Boyd, R. J. Gehr, S. A. Jenekhe, J. A. Osaheni, J. E. Sipe, and L. A. Weller-Brophy, “Enhanced nonlinear optical response of composite materials,” Phys. Rev. Lett. 74(10), 1871–1874 (1995). [CrossRef] [PubMed]
  11. N. N. Lepeshkin, A. Schweinsberg, G. Piredda, R. S. Bennink, and R. W. Boyd, “Enhanced nonlinear optical response of one-dimensional metal-dielectric photonic crystals,” Phys. Rev. Lett. 93(12), 123902 (2004). [CrossRef] [PubMed]
  12. R. L. Nelson and R. W. Boyd, “Enhanced electro-optic response of layered composite materials,” Appl. Phys. Lett. 74(17), 2417–2419 (1999). [CrossRef]
  13. J. H. Kang, J.-H. Choe, D. S. Kim, and Q. H. Park, “Substrate effect on aperture resonances in a thin metal film,” Opt. Express 17(18), 15652–15658 (2009). [CrossRef] [PubMed]
  14. E. Hendry, M. J. Lockyear, J. G. Rivas, L. Kuipers, and M. Bonn, “Ultrafast optical switching of the THz transmission through metallic subwavelength hole arrays,” Phys. Rev. B 75(23), 235305 (2007). [CrossRef]
  15. H.-T. Chen, W. J. Padilla, J. M. O. Zide, S. R. Bank, A. C. Gossard, A. J. Taylor, and R. D. Averitt, “Ultrafast optical switching of terahertz metamaterials fabricated on ErAs/GaAs nanoisland superlattices,” Opt. Lett. 32(12), 1620–1622 (2007). [CrossRef] [PubMed]
  16. W. J. Padilla, A. J. Taylor, C. Highstrete, M. Lee, and R. D. Averitt, “Dynamical electric and magnetic metamaterial response at terahertz frequencies,” Phys. Rev. Lett. 96(10), 107401 (2006). [CrossRef] [PubMed]
  17. W. L. Chan, H.-T. Chen, A. J. Taylor, I. Brener, M. J. Cich, and D. M. Mittleman, “A spatial light modulator for terahertz beams,” Appl. Phys. Lett. 94(21), 213511 (2009). [CrossRef]
  18. I. H. Libon, S. Baumgartner, M. Hempel, N. E. Hecker, J. Feldmann, M. Koch, and P. Dawson, “An optically controllable terahertz filter,” Appl. Phys. Lett. 76(20), 2821–2823 (2000). [CrossRef]
  19. W. L. Chan, M. L. Moravec, R. G. Baraniuk, and D. M. Mittleman, “Terahertz imaging with compressed sensing and phase retrieval,” Opt. Lett. 33(9), 974–976 (2008). [CrossRef] [PubMed]
  20. H. R. Park, Y. M. Park, H. S. Kim, J. S. Kyoung, M. A. Seo, D. J. Park, Y. H. Ahn, K. J. Ahn, and D. S. Kim, “Terahertz nanoresonators: Giant field enhancement and ultrabroadband performance,” Appl. Phys. Lett. 96(12), 121106 (2010). [CrossRef]
  21. F. J. Morin, “Oxides Which Show a Metal-to-Insulator Transition at the Neel Temperature,” Phys. Rev. Lett. 3(1), 34–36 (1959). [CrossRef]
  22. M. Nakajima, N. Takubo, Z. Hiroi, Y. Ueda, and T. Suemoto, “Photoinduced metallic state in VO2 proved by the terahertz pump-probe spectroscopy,” Appl. Phys. Lett. 92(1), 011907 (2008). [CrossRef]
  23. D. J. Hilton, R. P. Prasankumar, S. Fourmaux, A. Cavalleri, D. Brassard, M. A. El Khakani, J. C. Kieffer, A. J. Taylor, and R. D. Averitt, “Enhanced photosusceptibility near Tc for the light-induced insulator-to-metal phase transition in vanadium dioxide,” Phys. Rev. Lett. 99(22), 226401 (2007). [CrossRef]
  24. P. U. Jepsen, B. M. Fischer, A. Thoman, H. Helm, J. Y. Suh, R. Lopez, and R. F. Haglund, “Metal-insulator phase transition in a VO2 thin film observed with terahertz spectroscopy,” Phys. Rev. B 74(20), 205103 (2006). [CrossRef]
  25. A. Cavalleri, T. Dekorsy, H. H. W. Chong, J. C. Kieffer, and R. W. Schoenlein, “Evidence for a structurally-driven insulator-to-metal transition in VO2: A view from the ultrafast timescale,” Phys. Rev. B 70, 161102 (2004). [CrossRef]
  26. A. Cavalleri, C. Tóth, C. W. Siders, J. A. Squier, F. Ráksi, P. Forget, and J. C. Kieffer, “Femtosecond Structural Dynamics in VO2 during an Ultrafast Solid-Solid Phase Transition,” Phys. Rev. Lett. 87(23), 237401 (2001). [CrossRef] [PubMed]
  27. H.-T. Kim, B.-G. Chae, D.-H. Youn, S.-L. Maeng, G. Kim, K.-Y. Kang, and Y.-S. Lim, “Mechanism and observation of Mott transition in VO2-based two- and three-terminal devices,” N. J. Phys. 6, 52 (2004). [CrossRef]
  28. Y. Shin, J. Moon, H. Ju, and C. Park, “Growth and electrical properties of vanadium-dioxide thin films fabricated by magnetron sputtering,” J. Korean Phys. Soc. 52(6), 1828–1831 (2008). [CrossRef]
  29. S. J. Yun, J. W. Lim, B.-G. Chae, B. J. Kim, and H.-T. Kim, “Characteristics of vanadium dioxide films deposited by RF-magnetron sputter deposition technique using V-metal target,” Physica B 403, 1381–1383 (2008).
  30. B. G. Chae, H. T. Kim, and S. J. Yun, “Characteristics of W- and Ti-Doped VO2 Thin Films Prepared by Sol-Gel Method,” Electrochem. Solid State 11(6), D53–D55 (2008). [CrossRef]
  31. P. A. George, J. Strait, J. Dawlaty, S. Shivaraman, M. Chandrashekhar, F. Rana, and M. G. Spencer, “Ultrafast optical-pump terahertz-probe spectroscopy of the carrier relaxation and recombination dynamics in epitaxial graphene,” Nano Lett. 8(12), 4248–4251 (2008). [CrossRef]
  32. R. Huber, F. Tauser, A. Brodschelm, M. Bichler, G. Abstreiter, and A. Leitenstorfer, “How many-particle interactions develop after ultrafast excitation of an electron-hole plasma,” Nature 414(6861), 286–289 (2001). [CrossRef] [PubMed]
  33. G. Segschneider, F. Jacob, T. Löffler, H. G. Roskos, S. Tautz, P. Kiesel, and G. Döhler, “Free-carrier dynamics in low-temperature-grown GaAs at high excitation densities investigated by time-domain terahertz spectroscopy,” Phys. Rev. B 65(12), 125205 (2002). [CrossRef]
  34. D. Grischkowsky, S. Keiding, M. Vanexter, and C. Fattinger, “Far-Infrared Time-Domain Spectroscopy with Terahertz Beams of Dielectrics and Semiconductors,” J. Opt. Soc. Am. B 7(10), 2006–2015 (1990). [CrossRef]
  35. Z. Jiang, M. Li, and X. C. Zhang, “Dielectric constant measurement of thin films by differential time-domain spectroscopy,” Appl. Phys. Lett. 76(22), 3221–3223 (2000). [CrossRef]
  36. J. Lee, M. Seo, D. Park, D. Kim, S. Jeoung, Ch. Lienau, Q. H. Park, and P. Planken, “Shape resonance omni-directional terahertz filters with near-unity transmittance,” Opt. Express 14(3), 1253–1259 (2006). [CrossRef] [PubMed]
  37. G. Gallot and D. Grischkowsky, “Electro-optic detection of terahertz radiation,” J. Opt. Soc. Am. B 16(8), 1204–1212 (1999). [CrossRef]
  38. M. A. Seo, H. R. Park, S. M. Koo, D. J. Park, J. H. Kang, O. K. Suwal, S. S. Choi, P. C. M. Planken, G. S. Park, N. K. Park, Q. H. Park, and D. S. Kim, “Terahertz field enhancement by a metallic nano slit operating beyond the skin-depth limit,” Nat. Photonics 3(3), 152–156 (2009). [CrossRef]
  39. M. Seo, J. Kyoung, H. Park, S. Koo, H. S. Kim, H. Bernien, B. J. Kim, J. H. Choe, Y. H. Ahn, H.-T. Kim, N. Park, Q. H. Park, K. Ahn, and D. S. Kim, “Active terahertz nanoantennas based on VO2 phase transition,” Nano Lett. 10(6), 2064–2068 (2010). [CrossRef] [PubMed]
  40. J. W. Lee, M. A. Seo, D. J. Park, S. C. Jeoung, Q. H. Park, Ch. Lienau, and D. S. Kim, “Terahertz transparency at Fabry-Perot resonances of periodic slit arrays in a metal plate: experiment and theory,” Opt. Express 14(26), 12637–12643 (2006). [CrossRef] [PubMed]
  41. J. W. Lee, M. A. Seo, J. Y. Sohn, Y. H. Ahn, D. S. Kim, S. C. Jeoung, Ch. Lienau, and Q. H. Park, “Invisible plasmonic meta-materials through impedance matching to vacuum,” Opt. Express 13(26), 10681–10687 (2005). [CrossRef] [PubMed]
  42. D. J. Park, S. B. Choi, Y. H. Ahn, F. Rotermund, I. B. Sohn, C. Kang, M. S. Jeong, and D. S. Kim, “Terahertz near-field enhancement in narrow rectangular apertures on metal film,” Opt. Express 17(15), 12493–12501 (2009). [CrossRef] [PubMed]
  43. M. A. Seo, A. J. L. Adam, J. H. Kang, J. W. Lee, K. J. Ahn, Q. H. Park, P. C. M. Planken, and D. S. Kim, “Near field imaging of terahertz focusing onto rectangular apertures,” Opt. Express 16(25), 20484–20489 (2008). [CrossRef] [PubMed]
  44. F. J. García-Vidal, E. Moreno, J. A. Porto, and L. Martín-Moreno, “Transmission of light through a single rectangular hole,” Phys. Rev. Lett. 95(10), 103901 (2005). [CrossRef] [PubMed]
  45. J. W. Lee, M. A. Seo, D. H. Kang, K. S. Khim, S. C. Jeoung, and D. S. Kim, “Terahertz electromagnetic wave transmission through random arrays of single rectangular holes and slits in thin metallic sheets,” Phys. Rev. Lett. 99(13), 137401 (2007). [CrossRef] [PubMed]
  46. D. J. Park, S. B. Choi, Y. H. Ahn, Q. H. Park, and D. S. Kim, “Theoretical Study of Terahertz Near-Field Enhancement Assisted by Shape Resonance in Rectangular Hole Arrays in Metal Films,” J. Korean Phys. Soc. 54(1), 64–70 (2009). [CrossRef]
  47. N. Laman and D. Grischkowsky, “Terahertz conductivity of thin metal films,” Appl. Phys. Lett. 93(5), 051105 (2008). [CrossRef]
  48. T. I. Jeon, J. H. Son, K. H. An, Y. H. Lee, and Y. S. Lee, “Terahertz absorption and dispersion of fluorine-doped single-walled carbon nanotube,” J. Appl. Phys. 98(3), 034316 (2005). [CrossRef]
  49. A. Taflove, and S. C. Hagness, Computational Electromagnetics: The Finite-Difference Time-Domain Method (Artech House, Boston, 2000).

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