Abstract

Near-field subwavelength imaging has been realized at visible and mid-infrared frequencies, but it has not been achieved at near-infrared (NIR). In this work, the transparent conducting oxides (TCO)-based near-field superlenses working at NIR frequencies were proposed. As one of easily available TCO materials, Al-doped ZnO (AZO) was considered in both stratified ZnO-AZO-ZnO and single-layered AZO structures, which had the subwavelength resolution of better than λ/25 at a wavelength of 2.57μm andλ/20 at 2.01μm, respectively. These findings reveal that the TCO can find the applications not only in liquid-crystal displays, photovoltaic devices, and electromagnetic interface shielding, but also in superresolution and subsurface imaging at NIR frequencies.

© 2016 Optical Society of America

1. Introduction

Metamaterials refer to artificial structures, which are composed of natural materials, and they have exotic properties that natural materials do not have, such as negative refraction [1], ultra-high refractive index [2], and subwavelength imaging in the near- [3–5] and the far-field [6–8]. Ideally, a perfect lens for the subwavelength imaging is made from negative-index materials (NIMs) [9], overcoming the diffraction limit. Such NIMs have both negative dielectric permittivity and magnetic permeability, which are highly challenging yet at high frequencies. Fortunately, NIMs are not necessary for near-field subwavelength imaging thanks to the decoupling of the two types of linearly polarized light, TM (transverse magnetic) and TE (transverse electric) incident waves, in the near-field zone. Instead, regardless of magnetic permeability, the materials with negative dielectric permittivity can be used for near-field superlensing [3]. As experimentally demonstrated in the literature, a silver superlens was developed for the sub-diffraction-limited imaging with a resolution of better than λ/5 at a wavelength of 365 nm [4,5]. Besides the optical superlens, the mid-infrared (MIR) superlenses were extensively investigated, which could be made from SiC, perovskite oxides, GaAs, Si3N4, and graphene slabs [10–16]. At the superlensing frequencies, these negative-permittivity materials support highly confined surface plasmon polaritons (SPPs) such that the evanescent waves can be enhanced and recovered at the image plane [3,4]. It can be achieved by either resonant or non-resonant enhancement of SPPs: the former is fulfilled via εm=εd, where εm and εd are the permittivities of negative-permittivity materials and surrounding dielectric media, respectively, and the latter depends on the excitation of SPPs at ultra-small plasmon wavelengths λp, as demonstrated in graphene [15, 16].

Besides the negative permittivity, the resistive loss and retardation effects should be taken into account [17], which govern the resolution limit. Therefore, a low-loss negative-permittivity slab with small thickness is preferable to both resonant and non-resonant superlenses. Concerning the near-field superlenses working at near-infrared (NIR) frequencies, the noble metals, gold and silver, have significant imaginary permittivity, as compared with them at visible frequencies, which definitely limits the imaging resolution. Apart from the conventional noble metals, the most materials for MIR superlenses could not work at NIR frequencies due to the positive permittivity. Although the permittivity of graphene is negative at NIR, it is finite and cannot enhance the evanescent waves considerably. Thus far the development of near-field superlenses working at NIR frequencies still faces the challenges. Boltasseva et al. [18–20] pointed out that transparent conducting oxides (TCOs) have metal-like optical properties in the NIR range. Indeed, TCOs, as alternative plasmonic materials, have exhibited great potential in near-perfect absorbers [21–23], negative refraction [24], nonlinear optics [25], etc. other than subwavelength imaging. It is hopeful that the implementation of TCOs achieves a low resistive loss and negligible retardation effect as well as the excitation of SPPs.

In this work, we investigated the roles of Al:ZnO (AZO, Al-doped ZnO), one of TCOs, in NIR subwavelength imaging in the near-field. Based on the calculations of the optical transfer function (OTF), the propagation of evanescent waves was studied. It was found that AZO could effectively enhance the evanescent waves in both sandwiched ZnO-AZO-ZnO and single-layered AZO structures. The investigation on the near-field electromagnetic field distribution further confirmed that the subwavelength imaging could be achieved at the wavelengths around 2 μm. These findings exhibit the overwhelming advantages of TCOs in NIR subwavelength and subsurface imaging [26], and pave the way for engineering tunable TCOs-based superlens.

2. Structures and simulations

Two types of near-field superlens structures were studied: the stratified ZnO-AZO-ZnO and single-layered AZO. The former, as shown in Fig. 1(a), is a conventional sandwich structure, where undoped ZnO is selected as a surrounding dielectric medium considering the convenient fulfillment of εm=εd; the latter, as shown in Fig. 1(b), is an AZO single layer, surrounded by air. The permittivity of AZO is described by the Drude model [18], where the plasmon ωp and the collision frequencies Γ are determined by the carrier concentration n, the mobility µ, and the effective optical mass of conduction electrons m* [27].

 figure: Fig. 1

Fig. 1 Schematic illustration of two types of superlenses: (a) the ZnO-AZO-ZnO stratified superlens and (b) the single-layered AZO superlens. The gold double slits with various widths (w = 50 and 100 nm) and a fixed thickness of h = 10 nm were considered.

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OTF is the transmittance |T|2 through the stratified layers as a function of frequency and transverse wave vector kx [15]. To evaluate the propagation of evanescent waves, the OTF was calculated using a transfer matrix method [28,29]. The characteristic matrix of the j-th homogeneous layer is written as

Mj=[cosδjisinδj/ηjiηjsinδjcosδj],
whereδj and ηj are the phase thickness and the admittance of medium, respectively, and expressed as δj=kjzdj,ηj=kjz/ωεj [30]. Herekjz,dj, ω, and εj are the wave number in medium for the z axis component of the evanescent wave with kx>k0, the thickness, the radian frequency, and the permittivity, respectively. And kjz can be further written as
kjz=εjω2c2kx2,
where c and kx are the speed of light in vacuum and the x-component of wave number. Thus, the whole characteristics matrices for the stratified ZnO-AZO-ZnO and single-layered AZO superlenses are expressed as MZAZ=MZnOMAZOMZnO and MAAA=MairMAZOMair, respectively. The matrices are indicated as M=[ABCD]. Finally, transmission coefficient T can be written as [29]
T=2η0Aη0+Bη0ηN+1+C+DηN+1,
where η0 and ηN+1 are the admittance of incident and exit media. Because both media surrounding the structures are air, there is η0=ηN+1=ω2/c2kx2/ω.

According to the calculations of the OTF at the possible superlensing wavelengths, the corresponding imaging performance of the two types of superlenses was simulated using commercial software COMSOL based on the finite element method. As shown in Fig. 1(a) and 1(b), the gold double slits with various widths (e.g., w = 50 and 100 nm) and a fixed thickness of h were taken as objects for the superlens imaging, where only TM-polarized incident waves were considered for the excitation of SPPs. To rule out the effects of localized SPPs at the edges of the gold slits, the edges were rounded off [31]. The image plane was located at the bottom of the superlenses, d/2 away from the AZO layer. The simulations were carried out in two dimensions. The simulation domains were surrounded by the perfectly matched layer and assigned to the scattering boundary condition for mimicking the open boundary conditions [11].

3. Results and discussion

Given a carrier mobility of μ =30 cm2V1s1 and a free carrier concentration of n = 3.81×1020 cm3, the permittivity of AZO was plotted in Fig. 2(a), together with that of ZnO calculated through Cauchy model [32, 33], which had a finite imaginary part, as shown in Fig. 2(b). For a wavelength of 2.57 μm, the permittivity values of AZO and ZnO are εAZO=3.62+1.87i and εAZO=3.61, respectively, which have the approximate absolute values with opposite signs and allow for establishing a sandwich superlens. The single-layered AZO superlens is considered at a wavelength of 2.01 μm, since here the permittivity of AZO is εAZO=1+0.92i and has the approximate absolute value with that of surrounding medium, air. It was noted that the imaginary permittivity of AZO around 0.92~1.87 at the NIR wavelengths was comparable with that of silver in the visible wavelength, e.g., ~0.599 at a wavelength of 365 nm [34], which could guarantee the NIR subwavelength imaging of the TCO-based near-field superlenses.

 figure: Fig. 2

Fig. 2 (a) Calculated real and imaginary parts of the permittivity of AZO and (b) real part of the permittivity of ZnO. (c) OTF of AZO without surrounding media as a function of the thickness d and the transverse wave vector kx at a wavelength of 2.57  μm. (d) OTF for two types of superlens structures at the resonant wavelengths, together with that in free space.

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To investigate the enhancement effects of evanescent waves in AZO with various thicknesses, the OTF was calculated without consideration of surrounding media for simplicity. The transmission coefficient T was higher than 0.57 at the relatively large transverse wave vector kx=10k0 when the thickness of AZO was less than 50 nm, as shown in Fig. 2(c). Thus the thickness of AZO in both the sandwich and the single-layered superlenses was fixed to d = 50 nm in both superlenses considering the enhancement of evanescent waves and the satisfactory optoelectrical properties. Accordingly, the thickness of undoped ZnO in the stratified structure was d/2, i.e., 25 nm. The OTF of both superlenses were plotted in Fig. 2(d). The evanescent wave propagation in free space was also shown for comparison. In free space, the evanescent waves ( kx> k0,k0 is the wavenumber in free space) decay exponentially [35]. The transmission coefficient at kx> k0=10 is T = 0.09 in free space at λ=2.57 μm, whereas it is increased to T = 0.45 at the same wavelength through the ZnO-AZO-ZnO superlens. Similarly, the transmission coefficient is increased to T = 0.24 at λ=2.01 μm through the single-layered AZO superlens. It was found that both superlenses revealed the prominent enhancement of evanescent waves at the different wavelengths.

To illustrate the resolution capabilities of two types of superlenses intuitively, the effects of them on the imaging of gold double-slits were investigated. The amplitude distribution of x-component of electric field from object to image planes was calculated. As shown in Fig. 3(a), the electric fields through the double slits with a width of w = 100 nm are effectively transferred by the sandwich ZnO-AZO-ZnO superlens without obvious blur. For a smaller slit width of w = 50 nm, although the electric fields through the slits do not show a prominent reduction in amplitude, they are not well separated as shown in Fig. 3(b). From the line profile of energy density at the image plane in Fig. 3(c), the image contrast was calculated through V=(ImaxImin)/(Imax+Imin) [4]. In the case of the double slits width w = 100 nm, the value of V was unity, suggesting that two distinct peaks could be clearly resolved, whereas the image contrast V was only 0.23 in the case of w = 50 nm, revealing the impossible subwavelength imaging. According to image contrast, the lens could identify objects with a size around 100 nm, but could not work if the objects were smaller than 50 nm. Similarly, the resolution of the single-layered AZO superlens was studied, as shown in Fig. 3(d)-(f), where the distance between object and image planes was the same as the case of the sandwich ZnO-AZO-ZnO superlens. Figure 3(d) suggests that a clear image can be produced on image plane in the case of w = 100 nm, which is further confirmed through the image contrast V=1, as shown in Fig. 3(f). In the case of w = 50 nm, the electric fields through double slits merged at the image plane, as shown in Fig. 3(e). Correspondingly, the image contrast V was as low as 0.07 in Fig. 3(f). It revealed that the single-layered AZO superlens had a capability for subsurface imaging of the objects with a size around 100 nm. It was found that the proposed ZnO-AZO-ZnO superlens could achieve the subwavelength imaging with a resolution of better than λ/25at a wavelength of 2.57  μm, and the single-layered AZO superlens had a resolution of better thanλ/20 at a wavelength of 2.01 μm.

 figure: Fig. 3

Fig. 3 Amplitude distribution of x-component of electric field of the ZnO-AZO-ZnO stratified superlens imaging for the gold double silts with a width of (a) w = 100 nm and (b) w = 50 nm, and (c) their line profiles of energy density at image planes. In the case of the single-layered AZO superlens, the electric field distribution for (d) w = 100 nm, (e) w = 50 nm, and (f) the corresponding line profiles.

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4. Summary

In summary, we described the AZO-based structures, enabling the evanescent waves to be enhanced at NIR frequencies. Since AZO could easily find the surrounding media fulfilling the resonant condition with a low loss, the superresolution and subsurface imaging can be achieved by the AZO-based structures. The sandwich ZnO-AZO-ZnO superlens had a good subwavelength resolution of better thanλ/25 at a wavelength of 2.57 μm; the single-layered AZO superlens could reach a resolution overλ/20 at a wavelength of 2.01 μm. It was revealed that TCO materials could be good candidate for NIR subsurface and subwavelength imaging beyond noble metals. Thanks to the convenient doping of TCO materials and tailoring of the optoelectronic properties, they are promising for further development of active control of superlensing wavelength and resolution.

Funding

National Natural Science Foundation of China (Nos. Nos. 61574144, 11574167, 61275114, and 61290304); the Zhejiang Natural Science Foundation (No. LY17A040004); the Ningbo Natural Science Foundation (No. 2016A610053); and the K. C. Wong Magna Foundation in Ningbo University, China.

References and links

1. D. R. Smith, J. B. Pendry, and M. C. K. Wiltshire, “Metamaterials and negative refractive index,” Science 305(5685), 788–792 (2004). [CrossRef]   [PubMed]  

2. M. Choi, S. H. Lee, Y. Kim, S. B. Kang, J. Shin, M. H. Kwak, K. Y. Kang, Y. H. Lee, N. Park, and B. Min, “A terahertz metamaterial with unnaturally high refractive index,” Nature 470(7334), 369–373 (2011). [CrossRef]   [PubMed]  

3. D. Korobkin, Y. Urzhumov, and G. Shvets, “Enhanced near-field resolution in midinfrared using metamaterials,” J. Opt. Soc. Am. B 23(3), 468–478 (2006). [CrossRef]  

4. D. Melville and R. Blaikie, “Super-resolution imaging through a planar silver layer,” Opt. Express 13(6), 2127–2134 (2005). [CrossRef]   [PubMed]  

5. N. Fang, H. Lee, C. Sun, and X. Zhang, “Sub-diffraction-limited optical imaging with a silver superlens,” Science 308(5721), 534–537 (2005). [CrossRef]   [PubMed]  

6. Z. Liu, H. Lee, Y. Xiong, C. Sun, and X. Zhang, “Far-field optical hyperlens magnifying sub-diffraction-limited objects,” Science 315(5819), 1686 (2007). [CrossRef]   [PubMed]  

7. P. Cao, L. Cheng, X. Zhang, X. Huang, and H. Jiang, “Near-infrared plasmonic far-field nanofocusing effects with elongated depth of focus based on hybrid Au–dielectric–Ag subwavelength structures,” Plasmonics 11(5), 1219–1231 (2016). [CrossRef]  

8. A. Bisht, W. He, X. Wang, L. Y. L. Wu, X. Chen, and S. Li, “Hyperlensing at NIR frequencies using a hemispherical metallic nanowire lens in a sea-urchin geometry,” Nanoscale 8(20), 10669–10676 (2016). [CrossRef]   [PubMed]  

9. J. B. Pendry, “Negative refraction makes a perfect lens,” Phys. Rev. Lett. 85(18), 3966–3969 (2000). [CrossRef]   [PubMed]  

10. T. Taubner, D. Korobkin, Y. Urzhumov, G. Shvets, and R. Hillenbrand, “Near-field microscopy through a SiC superlens,” Science 313(5793), 1595 (2006). [CrossRef]   [PubMed]  

11. S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011). [CrossRef]   [PubMed]  

12. S. C. Kehr, P. Yu, Y. Liu, M. Parzefall, A. I. Khan, R. Jacob, M. T. Wenzel, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Microspectroscopy on perovskite-based superlens,” Opt. Mater. Express 1(5), 1051–1060 (2011). [CrossRef]  

13. M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015). [CrossRef]   [PubMed]  

14. L. Jung, B. Hauer, P. Li, M. Bornhöfft, J. Mayer, and T. Taubner, “Exploring the detection limits of infrared near-field microscopy regarding small buried structures and pushing them by exploiting superlens-related effects,” Opt. Express 24(5), 4431–4441 (2016). [CrossRef]  

15. P. Li and T. Taubner, “Broadband subwavelength imaging using a tunable graphene-lens,” ACS Nano 6(11), 10107–10114 (2012). [CrossRef]   [PubMed]  

16. P. Li, T. Wang, H. Böckmann, and T. Taubner, “Graphene-enhanced infrared near-field microscopy,” Nano Lett. 14(8), 4400–4405 (2014). [CrossRef]   [PubMed]  

17. J. T. Shen and P. M. Platzman, “Near field imaging with negative dielectric constant lenses,” Appl. Phys. Lett. 80(18), 3286–3288 (2002). [CrossRef]  

18. P. R. West, S. Ishii, G. V. Naik, N. K. Emani, V. M. Shalaev, and A. Boltasseva, “Searching for better plasmonic materials,” Laser Photonics Rev. 4(6), 795–808 (2010). [CrossRef]  

19. G. V. Naik, J. Kim, and A. Boltasseva, “Oxides and nitrides as alternative plasmonic materials in the optical range,” Opt. Mater. Express 1(6), 1090–1099 (2011). [CrossRef]  

20. G. V. Naik and A. Boltasseva, “Semiconductors for plasmonics and metamaterials,” Phys. Status Solidi Rapid Res. Lett. 4(10), 295–297 (2010). [CrossRef]  

21. J. Yoon, M. Zhou, M. A. Badsha, T. Y. Kim, Y. C. Jun, and C. K. Hwangbo, “Broadband epsilon-near-zero perfect absorption in the near-infrared,” Sci. Rep. 5, 12788 (2015). [CrossRef]   [PubMed]  

22. F. Liu, L. Cui, G. Lu, Y. Li, T. Yang, C. Xue, J. Xu, and G. Du, “Multiple and broadband near-perfect absorption in heterostructures containing transparent conducting oxides,” J. Appl. Phys. 119(8), 083106 (2016). [CrossRef]  

23. Y. Zhang, T. Wei, W. Dong, C. Huang, K. Zhang, Y. Sun, X. Chen, and N. Dai, “Near-perfect infrared absorption from dielectric multilayer of plasmonic aluminum-doped zinc oxide,” Appl. Phys. Lett. 102(21), 213117 (2013). [CrossRef]   [PubMed]  

24. G. V. Naik, J. Liu, A. V. Kildishev, V. M. Shalaev, and A. Boltasseva, “Demonstration of Al:ZnO as a plasmonic component for near-infrared metamaterials,” Proc. Natl. Acad. Sci. U.S.A. 109(23), 8834–8838 (2012). [CrossRef]   [PubMed]  

25. M. Z. Alam, I. De Leon, and R. W. Boyd, “Large optical nonlinearity of indium tin oxide in its epsilon-near-zero region,” Science 352(6287), 795–797 (2016). [CrossRef]   [PubMed]  

26. S. C. Kehr, R. G. P. McQuaid, L. Ortmann, T. Kämpfe, F. Kuschewski, D. Lang, J. Döring, J. M. Gregg, and L. M. Eng, “A local superlens,” ACS Photonics 3(1), 20–26 (2016). [CrossRef]  

27. G. V. Naik, V. M. Shalaev, and A. Boltasseva, “Alternative plasmonic materials: beyond gold and silver,” Adv. Mater. 25(24), 3264–3294 (2013). [CrossRef]   [PubMed]  

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

29. Z. Szabó, Y. Kiasat, and E. P. Li, “Subwavelength imaging with composite metamaterials,” J. Opt. Soc. Am. B 31(6), 1298–1307 (2014). [CrossRef]  

30. M. Liu and C. Jin, “Image quality deterioration due to phase fluctuation in layered superlens,” Optik (Stuttg.) 121(21), 1966–1975 (2010). [CrossRef]  

31. W. J. Lee, J. E. Kim, H. Y. Park, and M. H. Lee, “Silver superlens using antisymmetric surface plasmon modes,” Opt. Express 18(6), 5459–5465 (2010). [CrossRef]   [PubMed]  

32. Y. C. Liu, J. H. Hsieh, and S. K. Tung, “Extraction of optical constants of zinc oxide thin films by ellipsometry with various models,” Thin Solid Films 510(1–2), 32–38 (2006). [CrossRef]  

33. E. N. Cho, S. Park, and I. Yun, “Spectroscopic ellipsometry modeling of ZnO thin films with various O2 partial pressures,” Curr. Appl. Phys. 12(6), 1606–1610 (2012). [CrossRef]  

34. E. D. Palik, Handbook of Optical Constants of Solids (Academic Press, 1998).

35. L. Solymar and E. Shamonina, Waves in Metamaterials (Oxford University Press, 2009).

References

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  1. D. R. Smith, J. B. Pendry, and M. C. K. Wiltshire, “Metamaterials and negative refractive index,” Science 305(5685), 788–792 (2004).
    [Crossref] [PubMed]
  2. M. Choi, S. H. Lee, Y. Kim, S. B. Kang, J. Shin, M. H. Kwak, K. Y. Kang, Y. H. Lee, N. Park, and B. Min, “A terahertz metamaterial with unnaturally high refractive index,” Nature 470(7334), 369–373 (2011).
    [Crossref] [PubMed]
  3. D. Korobkin, Y. Urzhumov, and G. Shvets, “Enhanced near-field resolution in midinfrared using metamaterials,” J. Opt. Soc. Am. B 23(3), 468–478 (2006).
    [Crossref]
  4. D. Melville and R. Blaikie, “Super-resolution imaging through a planar silver layer,” Opt. Express 13(6), 2127–2134 (2005).
    [Crossref] [PubMed]
  5. N. Fang, H. Lee, C. Sun, and X. Zhang, “Sub-diffraction-limited optical imaging with a silver superlens,” Science 308(5721), 534–537 (2005).
    [Crossref] [PubMed]
  6. Z. Liu, H. Lee, Y. Xiong, C. Sun, and X. Zhang, “Far-field optical hyperlens magnifying sub-diffraction-limited objects,” Science 315(5819), 1686 (2007).
    [Crossref] [PubMed]
  7. P. Cao, L. Cheng, X. Zhang, X. Huang, and H. Jiang, “Near-infrared plasmonic far-field nanofocusing effects with elongated depth of focus based on hybrid Au–dielectric–Ag subwavelength structures,” Plasmonics 11(5), 1219–1231 (2016).
    [Crossref]
  8. A. Bisht, W. He, X. Wang, L. Y. L. Wu, X. Chen, and S. Li, “Hyperlensing at NIR frequencies using a hemispherical metallic nanowire lens in a sea-urchin geometry,” Nanoscale 8(20), 10669–10676 (2016).
    [Crossref] [PubMed]
  9. J. B. Pendry, “Negative refraction makes a perfect lens,” Phys. Rev. Lett. 85(18), 3966–3969 (2000).
    [Crossref] [PubMed]
  10. T. Taubner, D. Korobkin, Y. Urzhumov, G. Shvets, and R. Hillenbrand, “Near-field microscopy through a SiC superlens,” Science 313(5793), 1595 (2006).
    [Crossref] [PubMed]
  11. S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
    [Crossref] [PubMed]
  12. S. C. Kehr, P. Yu, Y. Liu, M. Parzefall, A. I. Khan, R. Jacob, M. T. Wenzel, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Microspectroscopy on perovskite-based superlens,” Opt. Mater. Express 1(5), 1051–1060 (2011).
    [Crossref]
  13. M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
    [Crossref] [PubMed]
  14. L. Jung, B. Hauer, P. Li, M. Bornhöfft, J. Mayer, and T. Taubner, “Exploring the detection limits of infrared near-field microscopy regarding small buried structures and pushing them by exploiting superlens-related effects,” Opt. Express 24(5), 4431–4441 (2016).
    [Crossref]
  15. P. Li and T. Taubner, “Broadband subwavelength imaging using a tunable graphene-lens,” ACS Nano 6(11), 10107–10114 (2012).
    [Crossref] [PubMed]
  16. P. Li, T. Wang, H. Böckmann, and T. Taubner, “Graphene-enhanced infrared near-field microscopy,” Nano Lett. 14(8), 4400–4405 (2014).
    [Crossref] [PubMed]
  17. J. T. Shen and P. M. Platzman, “Near field imaging with negative dielectric constant lenses,” Appl. Phys. Lett. 80(18), 3286–3288 (2002).
    [Crossref]
  18. P. R. West, S. Ishii, G. V. Naik, N. K. Emani, V. M. Shalaev, and A. Boltasseva, “Searching for better plasmonic materials,” Laser Photonics Rev. 4(6), 795–808 (2010).
    [Crossref]
  19. G. V. Naik, J. Kim, and A. Boltasseva, “Oxides and nitrides as alternative plasmonic materials in the optical range,” Opt. Mater. Express 1(6), 1090–1099 (2011).
    [Crossref]
  20. G. V. Naik and A. Boltasseva, “Semiconductors for plasmonics and metamaterials,” Phys. Status Solidi Rapid Res. Lett. 4(10), 295–297 (2010).
    [Crossref]
  21. J. Yoon, M. Zhou, M. A. Badsha, T. Y. Kim, Y. C. Jun, and C. K. Hwangbo, “Broadband epsilon-near-zero perfect absorption in the near-infrared,” Sci. Rep. 5, 12788 (2015).
    [Crossref] [PubMed]
  22. F. Liu, L. Cui, G. Lu, Y. Li, T. Yang, C. Xue, J. Xu, and G. Du, “Multiple and broadband near-perfect absorption in heterostructures containing transparent conducting oxides,” J. Appl. Phys. 119(8), 083106 (2016).
    [Crossref]
  23. Y. Zhang, T. Wei, W. Dong, C. Huang, K. Zhang, Y. Sun, X. Chen, and N. Dai, “Near-perfect infrared absorption from dielectric multilayer of plasmonic aluminum-doped zinc oxide,” Appl. Phys. Lett. 102(21), 213117 (2013).
    [Crossref] [PubMed]
  24. G. V. Naik, J. Liu, A. V. Kildishev, V. M. Shalaev, and A. Boltasseva, “Demonstration of Al:ZnO as a plasmonic component for near-infrared metamaterials,” Proc. Natl. Acad. Sci. U.S.A. 109(23), 8834–8838 (2012).
    [Crossref] [PubMed]
  25. M. Z. Alam, I. De Leon, and R. W. Boyd, “Large optical nonlinearity of indium tin oxide in its epsilon-near-zero region,” Science 352(6287), 795–797 (2016).
    [Crossref] [PubMed]
  26. S. C. Kehr, R. G. P. McQuaid, L. Ortmann, T. Kämpfe, F. Kuschewski, D. Lang, J. Döring, J. M. Gregg, and L. M. Eng, “A local superlens,” ACS Photonics 3(1), 20–26 (2016).
    [Crossref]
  27. G. V. Naik, V. M. Shalaev, and A. Boltasseva, “Alternative plasmonic materials: beyond gold and silver,” Adv. Mater. 25(24), 3264–3294 (2013).
    [Crossref] [PubMed]
  28. M. Born and E. Wolf, Principles of Optics (Cambridge University Press, 1999).
  29. Z. Szabó, Y. Kiasat, and E. P. Li, “Subwavelength imaging with composite metamaterials,” J. Opt. Soc. Am. B 31(6), 1298–1307 (2014).
    [Crossref]
  30. M. Liu and C. Jin, “Image quality deterioration due to phase fluctuation in layered superlens,” Optik (Stuttg.) 121(21), 1966–1975 (2010).
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  31. W. J. Lee, J. E. Kim, H. Y. Park, and M. H. Lee, “Silver superlens using antisymmetric surface plasmon modes,” Opt. Express 18(6), 5459–5465 (2010).
    [Crossref] [PubMed]
  32. Y. C. Liu, J. H. Hsieh, and S. K. Tung, “Extraction of optical constants of zinc oxide thin films by ellipsometry with various models,” Thin Solid Films 510(1–2), 32–38 (2006).
    [Crossref]
  33. E. N. Cho, S. Park, and I. Yun, “Spectroscopic ellipsometry modeling of ZnO thin films with various O2 partial pressures,” Curr. Appl. Phys. 12(6), 1606–1610 (2012).
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  34. E. D. Palik, Handbook of Optical Constants of Solids (Academic Press, 1998).
  35. L. Solymar and E. Shamonina, Waves in Metamaterials (Oxford University Press, 2009).

2016 (6)

P. Cao, L. Cheng, X. Zhang, X. Huang, and H. Jiang, “Near-infrared plasmonic far-field nanofocusing effects with elongated depth of focus based on hybrid Au–dielectric–Ag subwavelength structures,” Plasmonics 11(5), 1219–1231 (2016).
[Crossref]

A. Bisht, W. He, X. Wang, L. Y. L. Wu, X. Chen, and S. Li, “Hyperlensing at NIR frequencies using a hemispherical metallic nanowire lens in a sea-urchin geometry,” Nanoscale 8(20), 10669–10676 (2016).
[Crossref] [PubMed]

L. Jung, B. Hauer, P. Li, M. Bornhöfft, J. Mayer, and T. Taubner, “Exploring the detection limits of infrared near-field microscopy regarding small buried structures and pushing them by exploiting superlens-related effects,” Opt. Express 24(5), 4431–4441 (2016).
[Crossref]

F. Liu, L. Cui, G. Lu, Y. Li, T. Yang, C. Xue, J. Xu, and G. Du, “Multiple and broadband near-perfect absorption in heterostructures containing transparent conducting oxides,” J. Appl. Phys. 119(8), 083106 (2016).
[Crossref]

M. Z. Alam, I. De Leon, and R. W. Boyd, “Large optical nonlinearity of indium tin oxide in its epsilon-near-zero region,” Science 352(6287), 795–797 (2016).
[Crossref] [PubMed]

S. C. Kehr, R. G. P. McQuaid, L. Ortmann, T. Kämpfe, F. Kuschewski, D. Lang, J. Döring, J. M. Gregg, and L. M. Eng, “A local superlens,” ACS Photonics 3(1), 20–26 (2016).
[Crossref]

2015 (2)

J. Yoon, M. Zhou, M. A. Badsha, T. Y. Kim, Y. C. Jun, and C. K. Hwangbo, “Broadband epsilon-near-zero perfect absorption in the near-infrared,” Sci. Rep. 5, 12788 (2015).
[Crossref] [PubMed]

M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
[Crossref] [PubMed]

2014 (2)

P. Li, T. Wang, H. Böckmann, and T. Taubner, “Graphene-enhanced infrared near-field microscopy,” Nano Lett. 14(8), 4400–4405 (2014).
[Crossref] [PubMed]

Z. Szabó, Y. Kiasat, and E. P. Li, “Subwavelength imaging with composite metamaterials,” J. Opt. Soc. Am. B 31(6), 1298–1307 (2014).
[Crossref]

2013 (2)

G. V. Naik, V. M. Shalaev, and A. Boltasseva, “Alternative plasmonic materials: beyond gold and silver,” Adv. Mater. 25(24), 3264–3294 (2013).
[Crossref] [PubMed]

Y. Zhang, T. Wei, W. Dong, C. Huang, K. Zhang, Y. Sun, X. Chen, and N. Dai, “Near-perfect infrared absorption from dielectric multilayer of plasmonic aluminum-doped zinc oxide,” Appl. Phys. Lett. 102(21), 213117 (2013).
[Crossref] [PubMed]

2012 (3)

G. V. Naik, J. Liu, A. V. Kildishev, V. M. Shalaev, and A. Boltasseva, “Demonstration of Al:ZnO as a plasmonic component for near-infrared metamaterials,” Proc. Natl. Acad. Sci. U.S.A. 109(23), 8834–8838 (2012).
[Crossref] [PubMed]

E. N. Cho, S. Park, and I. Yun, “Spectroscopic ellipsometry modeling of ZnO thin films with various O2 partial pressures,” Curr. Appl. Phys. 12(6), 1606–1610 (2012).
[Crossref]

P. Li and T. Taubner, “Broadband subwavelength imaging using a tunable graphene-lens,” ACS Nano 6(11), 10107–10114 (2012).
[Crossref] [PubMed]

2011 (4)

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

S. C. Kehr, P. Yu, Y. Liu, M. Parzefall, A. I. Khan, R. Jacob, M. T. Wenzel, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Microspectroscopy on perovskite-based superlens,” Opt. Mater. Express 1(5), 1051–1060 (2011).
[Crossref]

M. Choi, S. H. Lee, Y. Kim, S. B. Kang, J. Shin, M. H. Kwak, K. Y. Kang, Y. H. Lee, N. Park, and B. Min, “A terahertz metamaterial with unnaturally high refractive index,” Nature 470(7334), 369–373 (2011).
[Crossref] [PubMed]

G. V. Naik, J. Kim, and A. Boltasseva, “Oxides and nitrides as alternative plasmonic materials in the optical range,” Opt. Mater. Express 1(6), 1090–1099 (2011).
[Crossref]

2010 (4)

G. V. Naik and A. Boltasseva, “Semiconductors for plasmonics and metamaterials,” Phys. Status Solidi Rapid Res. Lett. 4(10), 295–297 (2010).
[Crossref]

P. R. West, S. Ishii, G. V. Naik, N. K. Emani, V. M. Shalaev, and A. Boltasseva, “Searching for better plasmonic materials,” Laser Photonics Rev. 4(6), 795–808 (2010).
[Crossref]

M. Liu and C. Jin, “Image quality deterioration due to phase fluctuation in layered superlens,” Optik (Stuttg.) 121(21), 1966–1975 (2010).
[Crossref]

W. J. Lee, J. E. Kim, H. Y. Park, and M. H. Lee, “Silver superlens using antisymmetric surface plasmon modes,” Opt. Express 18(6), 5459–5465 (2010).
[Crossref] [PubMed]

2007 (1)

Z. Liu, H. Lee, Y. Xiong, C. Sun, and X. Zhang, “Far-field optical hyperlens magnifying sub-diffraction-limited objects,” Science 315(5819), 1686 (2007).
[Crossref] [PubMed]

2006 (3)

D. Korobkin, Y. Urzhumov, and G. Shvets, “Enhanced near-field resolution in midinfrared using metamaterials,” J. Opt. Soc. Am. B 23(3), 468–478 (2006).
[Crossref]

T. Taubner, D. Korobkin, Y. Urzhumov, G. Shvets, and R. Hillenbrand, “Near-field microscopy through a SiC superlens,” Science 313(5793), 1595 (2006).
[Crossref] [PubMed]

Y. C. Liu, J. H. Hsieh, and S. K. Tung, “Extraction of optical constants of zinc oxide thin films by ellipsometry with various models,” Thin Solid Films 510(1–2), 32–38 (2006).
[Crossref]

2005 (2)

D. Melville and R. Blaikie, “Super-resolution imaging through a planar silver layer,” Opt. Express 13(6), 2127–2134 (2005).
[Crossref] [PubMed]

N. Fang, H. Lee, C. Sun, and X. Zhang, “Sub-diffraction-limited optical imaging with a silver superlens,” Science 308(5721), 534–537 (2005).
[Crossref] [PubMed]

2004 (1)

D. R. Smith, J. B. Pendry, and M. C. K. Wiltshire, “Metamaterials and negative refractive index,” Science 305(5685), 788–792 (2004).
[Crossref] [PubMed]

2002 (1)

J. T. Shen and P. M. Platzman, “Near field imaging with negative dielectric constant lenses,” Appl. Phys. Lett. 80(18), 3286–3288 (2002).
[Crossref]

2000 (1)

J. B. Pendry, “Negative refraction makes a perfect lens,” Phys. Rev. Lett. 85(18), 3966–3969 (2000).
[Crossref] [PubMed]

Alam, M. Z.

M. Z. Alam, I. De Leon, and R. W. Boyd, “Large optical nonlinearity of indium tin oxide in its epsilon-near-zero region,” Science 352(6287), 795–797 (2016).
[Crossref] [PubMed]

Badsha, M. A.

J. Yoon, M. Zhou, M. A. Badsha, T. Y. Kim, Y. C. Jun, and C. K. Hwangbo, “Broadband epsilon-near-zero perfect absorption in the near-infrared,” Sci. Rep. 5, 12788 (2015).
[Crossref] [PubMed]

Bisht, A.

A. Bisht, W. He, X. Wang, L. Y. L. Wu, X. Chen, and S. Li, “Hyperlensing at NIR frequencies using a hemispherical metallic nanowire lens in a sea-urchin geometry,” Nanoscale 8(20), 10669–10676 (2016).
[Crossref] [PubMed]

Blaikie, R.

Böckmann, H.

P. Li, T. Wang, H. Böckmann, and T. Taubner, “Graphene-enhanced infrared near-field microscopy,” Nano Lett. 14(8), 4400–4405 (2014).
[Crossref] [PubMed]

Boltasseva, A.

G. V. Naik, V. M. Shalaev, and A. Boltasseva, “Alternative plasmonic materials: beyond gold and silver,” Adv. Mater. 25(24), 3264–3294 (2013).
[Crossref] [PubMed]

G. V. Naik, J. Liu, A. V. Kildishev, V. M. Shalaev, and A. Boltasseva, “Demonstration of Al:ZnO as a plasmonic component for near-infrared metamaterials,” Proc. Natl. Acad. Sci. U.S.A. 109(23), 8834–8838 (2012).
[Crossref] [PubMed]

G. V. Naik, J. Kim, and A. Boltasseva, “Oxides and nitrides as alternative plasmonic materials in the optical range,” Opt. Mater. Express 1(6), 1090–1099 (2011).
[Crossref]

G. V. Naik and A. Boltasseva, “Semiconductors for plasmonics and metamaterials,” Phys. Status Solidi Rapid Res. Lett. 4(10), 295–297 (2010).
[Crossref]

P. R. West, S. Ishii, G. V. Naik, N. K. Emani, V. M. Shalaev, and A. Boltasseva, “Searching for better plasmonic materials,” Laser Photonics Rev. 4(6), 795–808 (2010).
[Crossref]

Bornhöfft, M.

Boyd, R. W.

M. Z. Alam, I. De Leon, and R. W. Boyd, “Large optical nonlinearity of indium tin oxide in its epsilon-near-zero region,” Science 352(6287), 795–797 (2016).
[Crossref] [PubMed]

Cao, P.

P. Cao, L. Cheng, X. Zhang, X. Huang, and H. Jiang, “Near-infrared plasmonic far-field nanofocusing effects with elongated depth of focus based on hybrid Au–dielectric–Ag subwavelength structures,” Plasmonics 11(5), 1219–1231 (2016).
[Crossref]

Chen, X.

A. Bisht, W. He, X. Wang, L. Y. L. Wu, X. Chen, and S. Li, “Hyperlensing at NIR frequencies using a hemispherical metallic nanowire lens in a sea-urchin geometry,” Nanoscale 8(20), 10669–10676 (2016).
[Crossref] [PubMed]

Y. Zhang, T. Wei, W. Dong, C. Huang, K. Zhang, Y. Sun, X. Chen, and N. Dai, “Near-perfect infrared absorption from dielectric multilayer of plasmonic aluminum-doped zinc oxide,” Appl. Phys. Lett. 102(21), 213117 (2013).
[Crossref] [PubMed]

Cheng, L.

P. Cao, L. Cheng, X. Zhang, X. Huang, and H. Jiang, “Near-infrared plasmonic far-field nanofocusing effects with elongated depth of focus based on hybrid Au–dielectric–Ag subwavelength structures,” Plasmonics 11(5), 1219–1231 (2016).
[Crossref]

Cho, E. N.

E. N. Cho, S. Park, and I. Yun, “Spectroscopic ellipsometry modeling of ZnO thin films with various O2 partial pressures,” Curr. Appl. Phys. 12(6), 1606–1610 (2012).
[Crossref]

Choi, M.

M. Choi, S. H. Lee, Y. Kim, S. B. Kang, J. Shin, M. H. Kwak, K. Y. Kang, Y. H. Lee, N. Park, and B. Min, “A terahertz metamaterial with unnaturally high refractive index,” Nature 470(7334), 369–373 (2011).
[Crossref] [PubMed]

Cui, L.

F. Liu, L. Cui, G. Lu, Y. Li, T. Yang, C. Xue, J. Xu, and G. Du, “Multiple and broadband near-perfect absorption in heterostructures containing transparent conducting oxides,” J. Appl. Phys. 119(8), 083106 (2016).
[Crossref]

Dai, N.

Y. Zhang, T. Wei, W. Dong, C. Huang, K. Zhang, Y. Sun, X. Chen, and N. Dai, “Near-perfect infrared absorption from dielectric multilayer of plasmonic aluminum-doped zinc oxide,” Appl. Phys. Lett. 102(21), 213117 (2013).
[Crossref] [PubMed]

De Leon, I.

M. Z. Alam, I. De Leon, and R. W. Boyd, “Large optical nonlinearity of indium tin oxide in its epsilon-near-zero region,” Science 352(6287), 795–797 (2016).
[Crossref] [PubMed]

Dong, W.

Y. Zhang, T. Wei, W. Dong, C. Huang, K. Zhang, Y. Sun, X. Chen, and N. Dai, “Near-perfect infrared absorption from dielectric multilayer of plasmonic aluminum-doped zinc oxide,” Appl. Phys. Lett. 102(21), 213117 (2013).
[Crossref] [PubMed]

Döring, J.

S. C. Kehr, R. G. P. McQuaid, L. Ortmann, T. Kämpfe, F. Kuschewski, D. Lang, J. Döring, J. M. Gregg, and L. M. Eng, “A local superlens,” ACS Photonics 3(1), 20–26 (2016).
[Crossref]

M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
[Crossref] [PubMed]

Du, G.

F. Liu, L. Cui, G. Lu, Y. Li, T. Yang, C. Xue, J. Xu, and G. Du, “Multiple and broadband near-perfect absorption in heterostructures containing transparent conducting oxides,” J. Appl. Phys. 119(8), 083106 (2016).
[Crossref]

Emani, N. K.

P. R. West, S. Ishii, G. V. Naik, N. K. Emani, V. M. Shalaev, and A. Boltasseva, “Searching for better plasmonic materials,” Laser Photonics Rev. 4(6), 795–808 (2010).
[Crossref]

Eng, L. M.

S. C. Kehr, R. G. P. McQuaid, L. Ortmann, T. Kämpfe, F. Kuschewski, D. Lang, J. Döring, J. M. Gregg, and L. M. Eng, “A local superlens,” ACS Photonics 3(1), 20–26 (2016).
[Crossref]

M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
[Crossref] [PubMed]

S. C. Kehr, P. Yu, Y. Liu, M. Parzefall, A. I. Khan, R. Jacob, M. T. Wenzel, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Microspectroscopy on perovskite-based superlens,” Opt. Mater. Express 1(5), 1051–1060 (2011).
[Crossref]

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

Fang, N.

N. Fang, H. Lee, C. Sun, and X. Zhang, “Sub-diffraction-limited optical imaging with a silver superlens,” Science 308(5721), 534–537 (2005).
[Crossref] [PubMed]

Fehrenbacher, M.

M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
[Crossref] [PubMed]

Gajek, M.

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

Gregg, J. M.

S. C. Kehr, R. G. P. McQuaid, L. Ortmann, T. Kämpfe, F. Kuschewski, D. Lang, J. Döring, J. M. Gregg, and L. M. Eng, “A local superlens,” ACS Photonics 3(1), 20–26 (2016).
[Crossref]

Hauer, B.

He, W.

A. Bisht, W. He, X. Wang, L. Y. L. Wu, X. Chen, and S. Li, “Hyperlensing at NIR frequencies using a hemispherical metallic nanowire lens in a sea-urchin geometry,” Nanoscale 8(20), 10669–10676 (2016).
[Crossref] [PubMed]

Helm, M.

M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
[Crossref] [PubMed]

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

S. C. Kehr, P. Yu, Y. Liu, M. Parzefall, A. I. Khan, R. Jacob, M. T. Wenzel, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Microspectroscopy on perovskite-based superlens,” Opt. Mater. Express 1(5), 1051–1060 (2011).
[Crossref]

Hillenbrand, R.

T. Taubner, D. Korobkin, Y. Urzhumov, G. Shvets, and R. Hillenbrand, “Near-field microscopy through a SiC superlens,” Science 313(5793), 1595 (2006).
[Crossref] [PubMed]

Hsieh, J. H.

Y. C. Liu, J. H. Hsieh, and S. K. Tung, “Extraction of optical constants of zinc oxide thin films by ellipsometry with various models,” Thin Solid Films 510(1–2), 32–38 (2006).
[Crossref]

Huang, C.

Y. Zhang, T. Wei, W. Dong, C. Huang, K. Zhang, Y. Sun, X. Chen, and N. Dai, “Near-perfect infrared absorption from dielectric multilayer of plasmonic aluminum-doped zinc oxide,” Appl. Phys. Lett. 102(21), 213117 (2013).
[Crossref] [PubMed]

Huang, X.

P. Cao, L. Cheng, X. Zhang, X. Huang, and H. Jiang, “Near-infrared plasmonic far-field nanofocusing effects with elongated depth of focus based on hybrid Au–dielectric–Ag subwavelength structures,” Plasmonics 11(5), 1219–1231 (2016).
[Crossref]

Huo, Y.

M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
[Crossref] [PubMed]

Hwangbo, C. K.

J. Yoon, M. Zhou, M. A. Badsha, T. Y. Kim, Y. C. Jun, and C. K. Hwangbo, “Broadband epsilon-near-zero perfect absorption in the near-infrared,” Sci. Rep. 5, 12788 (2015).
[Crossref] [PubMed]

Ishii, S.

P. R. West, S. Ishii, G. V. Naik, N. K. Emani, V. M. Shalaev, and A. Boltasseva, “Searching for better plasmonic materials,” Laser Photonics Rev. 4(6), 795–808 (2010).
[Crossref]

Jacob, R.

S. C. Kehr, P. Yu, Y. Liu, M. Parzefall, A. I. Khan, R. Jacob, M. T. Wenzel, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Microspectroscopy on perovskite-based superlens,” Opt. Mater. Express 1(5), 1051–1060 (2011).
[Crossref]

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

Jiang, H.

P. Cao, L. Cheng, X. Zhang, X. Huang, and H. Jiang, “Near-infrared plasmonic far-field nanofocusing effects with elongated depth of focus based on hybrid Au–dielectric–Ag subwavelength structures,” Plasmonics 11(5), 1219–1231 (2016).
[Crossref]

Jin, C.

M. Liu and C. Jin, “Image quality deterioration due to phase fluctuation in layered superlens,” Optik (Stuttg.) 121(21), 1966–1975 (2010).
[Crossref]

Jun, Y. C.

J. Yoon, M. Zhou, M. A. Badsha, T. Y. Kim, Y. C. Jun, and C. K. Hwangbo, “Broadband epsilon-near-zero perfect absorption in the near-infrared,” Sci. Rep. 5, 12788 (2015).
[Crossref] [PubMed]

Jung, L.

Kämpfe, T.

S. C. Kehr, R. G. P. McQuaid, L. Ortmann, T. Kämpfe, F. Kuschewski, D. Lang, J. Döring, J. M. Gregg, and L. M. Eng, “A local superlens,” ACS Photonics 3(1), 20–26 (2016).
[Crossref]

Kang, K. Y.

M. Choi, S. H. Lee, Y. Kim, S. B. Kang, J. Shin, M. H. Kwak, K. Y. Kang, Y. H. Lee, N. Park, and B. Min, “A terahertz metamaterial with unnaturally high refractive index,” Nature 470(7334), 369–373 (2011).
[Crossref] [PubMed]

Kang, S. B.

M. Choi, S. H. Lee, Y. Kim, S. B. Kang, J. Shin, M. H. Kwak, K. Y. Kang, Y. H. Lee, N. Park, and B. Min, “A terahertz metamaterial with unnaturally high refractive index,” Nature 470(7334), 369–373 (2011).
[Crossref] [PubMed]

Kehr, S. C.

S. C. Kehr, R. G. P. McQuaid, L. Ortmann, T. Kämpfe, F. Kuschewski, D. Lang, J. Döring, J. M. Gregg, and L. M. Eng, “A local superlens,” ACS Photonics 3(1), 20–26 (2016).
[Crossref]

M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
[Crossref] [PubMed]

S. C. Kehr, P. Yu, Y. Liu, M. Parzefall, A. I. Khan, R. Jacob, M. T. Wenzel, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Microspectroscopy on perovskite-based superlens,” Opt. Mater. Express 1(5), 1051–1060 (2011).
[Crossref]

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

Khan, A. I.

Kiasat, Y.

Kildishev, A. V.

G. V. Naik, J. Liu, A. V. Kildishev, V. M. Shalaev, and A. Boltasseva, “Demonstration of Al:ZnO as a plasmonic component for near-infrared metamaterials,” Proc. Natl. Acad. Sci. U.S.A. 109(23), 8834–8838 (2012).
[Crossref] [PubMed]

Kim, J.

Kim, J. E.

Kim, T. Y.

J. Yoon, M. Zhou, M. A. Badsha, T. Y. Kim, Y. C. Jun, and C. K. Hwangbo, “Broadband epsilon-near-zero perfect absorption in the near-infrared,” Sci. Rep. 5, 12788 (2015).
[Crossref] [PubMed]

Kim, Y.

M. Choi, S. H. Lee, Y. Kim, S. B. Kang, J. Shin, M. H. Kwak, K. Y. Kang, Y. H. Lee, N. Park, and B. Min, “A terahertz metamaterial with unnaturally high refractive index,” Nature 470(7334), 369–373 (2011).
[Crossref] [PubMed]

Korobkin, D.

D. Korobkin, Y. Urzhumov, and G. Shvets, “Enhanced near-field resolution in midinfrared using metamaterials,” J. Opt. Soc. Am. B 23(3), 468–478 (2006).
[Crossref]

T. Taubner, D. Korobkin, Y. Urzhumov, G. Shvets, and R. Hillenbrand, “Near-field microscopy through a SiC superlens,” Science 313(5793), 1595 (2006).
[Crossref] [PubMed]

Kuschewski, F.

S. C. Kehr, R. G. P. McQuaid, L. Ortmann, T. Kämpfe, F. Kuschewski, D. Lang, J. Döring, J. M. Gregg, and L. M. Eng, “A local superlens,” ACS Photonics 3(1), 20–26 (2016).
[Crossref]

Kwak, M. H.

M. Choi, S. H. Lee, Y. Kim, S. B. Kang, J. Shin, M. H. Kwak, K. Y. Kang, Y. H. Lee, N. Park, and B. Min, “A terahertz metamaterial with unnaturally high refractive index,” Nature 470(7334), 369–373 (2011).
[Crossref] [PubMed]

Lang, D.

S. C. Kehr, R. G. P. McQuaid, L. Ortmann, T. Kämpfe, F. Kuschewski, D. Lang, J. Döring, J. M. Gregg, and L. M. Eng, “A local superlens,” ACS Photonics 3(1), 20–26 (2016).
[Crossref]

Lee, H.

Z. Liu, H. Lee, Y. Xiong, C. Sun, and X. Zhang, “Far-field optical hyperlens magnifying sub-diffraction-limited objects,” Science 315(5819), 1686 (2007).
[Crossref] [PubMed]

N. Fang, H. Lee, C. Sun, and X. Zhang, “Sub-diffraction-limited optical imaging with a silver superlens,” Science 308(5721), 534–537 (2005).
[Crossref] [PubMed]

Lee, M. H.

Lee, S. H.

M. Choi, S. H. Lee, Y. Kim, S. B. Kang, J. Shin, M. H. Kwak, K. Y. Kang, Y. H. Lee, N. Park, and B. Min, “A terahertz metamaterial with unnaturally high refractive index,” Nature 470(7334), 369–373 (2011).
[Crossref] [PubMed]

Lee, W. J.

Lee, Y. H.

M. Choi, S. H. Lee, Y. Kim, S. B. Kang, J. Shin, M. H. Kwak, K. Y. Kang, Y. H. Lee, N. Park, and B. Min, “A terahertz metamaterial with unnaturally high refractive index,” Nature 470(7334), 369–373 (2011).
[Crossref] [PubMed]

Li, E. P.

Li, P.

L. Jung, B. Hauer, P. Li, M. Bornhöfft, J. Mayer, and T. Taubner, “Exploring the detection limits of infrared near-field microscopy regarding small buried structures and pushing them by exploiting superlens-related effects,” Opt. Express 24(5), 4431–4441 (2016).
[Crossref]

P. Li, T. Wang, H. Böckmann, and T. Taubner, “Graphene-enhanced infrared near-field microscopy,” Nano Lett. 14(8), 4400–4405 (2014).
[Crossref] [PubMed]

P. Li and T. Taubner, “Broadband subwavelength imaging using a tunable graphene-lens,” ACS Nano 6(11), 10107–10114 (2012).
[Crossref] [PubMed]

Li, S.

A. Bisht, W. He, X. Wang, L. Y. L. Wu, X. Chen, and S. Li, “Hyperlensing at NIR frequencies using a hemispherical metallic nanowire lens in a sea-urchin geometry,” Nanoscale 8(20), 10669–10676 (2016).
[Crossref] [PubMed]

Li, Y.

F. Liu, L. Cui, G. Lu, Y. Li, T. Yang, C. Xue, J. Xu, and G. Du, “Multiple and broadband near-perfect absorption in heterostructures containing transparent conducting oxides,” J. Appl. Phys. 119(8), 083106 (2016).
[Crossref]

Liu, F.

F. Liu, L. Cui, G. Lu, Y. Li, T. Yang, C. Xue, J. Xu, and G. Du, “Multiple and broadband near-perfect absorption in heterostructures containing transparent conducting oxides,” J. Appl. Phys. 119(8), 083106 (2016).
[Crossref]

Liu, J.

G. V. Naik, J. Liu, A. V. Kildishev, V. M. Shalaev, and A. Boltasseva, “Demonstration of Al:ZnO as a plasmonic component for near-infrared metamaterials,” Proc. Natl. Acad. Sci. U.S.A. 109(23), 8834–8838 (2012).
[Crossref] [PubMed]

Liu, M.

M. Liu and C. Jin, “Image quality deterioration due to phase fluctuation in layered superlens,” Optik (Stuttg.) 121(21), 1966–1975 (2010).
[Crossref]

Liu, Y.

M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
[Crossref] [PubMed]

S. C. Kehr, P. Yu, Y. Liu, M. Parzefall, A. I. Khan, R. Jacob, M. T. Wenzel, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Microspectroscopy on perovskite-based superlens,” Opt. Mater. Express 1(5), 1051–1060 (2011).
[Crossref]

Liu, Y. C.

Y. C. Liu, J. H. Hsieh, and S. K. Tung, “Extraction of optical constants of zinc oxide thin films by ellipsometry with various models,” Thin Solid Films 510(1–2), 32–38 (2006).
[Crossref]

Liu, Y. M.

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

Liu, Z.

Z. Liu, H. Lee, Y. Xiong, C. Sun, and X. Zhang, “Far-field optical hyperlens magnifying sub-diffraction-limited objects,” Science 315(5819), 1686 (2007).
[Crossref] [PubMed]

Lu, G.

F. Liu, L. Cui, G. Lu, Y. Li, T. Yang, C. Xue, J. Xu, and G. Du, “Multiple and broadband near-perfect absorption in heterostructures containing transparent conducting oxides,” J. Appl. Phys. 119(8), 083106 (2016).
[Crossref]

Martin, L. W.

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

Mayer, J.

McQuaid, R. G. P.

S. C. Kehr, R. G. P. McQuaid, L. Ortmann, T. Kämpfe, F. Kuschewski, D. Lang, J. Döring, J. M. Gregg, and L. M. Eng, “A local superlens,” ACS Photonics 3(1), 20–26 (2016).
[Crossref]

Melville, D.

Min, B.

M. Choi, S. H. Lee, Y. Kim, S. B. Kang, J. Shin, M. H. Kwak, K. Y. Kang, Y. H. Lee, N. Park, and B. Min, “A terahertz metamaterial with unnaturally high refractive index,” Nature 470(7334), 369–373 (2011).
[Crossref] [PubMed]

Naik, G. V.

G. V. Naik, V. M. Shalaev, and A. Boltasseva, “Alternative plasmonic materials: beyond gold and silver,” Adv. Mater. 25(24), 3264–3294 (2013).
[Crossref] [PubMed]

G. V. Naik, J. Liu, A. V. Kildishev, V. M. Shalaev, and A. Boltasseva, “Demonstration of Al:ZnO as a plasmonic component for near-infrared metamaterials,” Proc. Natl. Acad. Sci. U.S.A. 109(23), 8834–8838 (2012).
[Crossref] [PubMed]

G. V. Naik, J. Kim, and A. Boltasseva, “Oxides and nitrides as alternative plasmonic materials in the optical range,” Opt. Mater. Express 1(6), 1090–1099 (2011).
[Crossref]

P. R. West, S. Ishii, G. V. Naik, N. K. Emani, V. M. Shalaev, and A. Boltasseva, “Searching for better plasmonic materials,” Laser Photonics Rev. 4(6), 795–808 (2010).
[Crossref]

G. V. Naik and A. Boltasseva, “Semiconductors for plasmonics and metamaterials,” Phys. Status Solidi Rapid Res. Lett. 4(10), 295–297 (2010).
[Crossref]

Ortmann, L.

S. C. Kehr, R. G. P. McQuaid, L. Ortmann, T. Kämpfe, F. Kuschewski, D. Lang, J. Döring, J. M. Gregg, and L. M. Eng, “A local superlens,” ACS Photonics 3(1), 20–26 (2016).
[Crossref]

Park, H. Y.

Park, N.

M. Choi, S. H. Lee, Y. Kim, S. B. Kang, J. Shin, M. H. Kwak, K. Y. Kang, Y. H. Lee, N. Park, and B. Min, “A terahertz metamaterial with unnaturally high refractive index,” Nature 470(7334), 369–373 (2011).
[Crossref] [PubMed]

Park, S.

E. N. Cho, S. Park, and I. Yun, “Spectroscopic ellipsometry modeling of ZnO thin films with various O2 partial pressures,” Curr. Appl. Phys. 12(6), 1606–1610 (2012).
[Crossref]

Parzefall, M.

Pendry, J. B.

D. R. Smith, J. B. Pendry, and M. C. K. Wiltshire, “Metamaterials and negative refractive index,” Science 305(5685), 788–792 (2004).
[Crossref] [PubMed]

J. B. Pendry, “Negative refraction makes a perfect lens,” Phys. Rev. Lett. 85(18), 3966–3969 (2000).
[Crossref] [PubMed]

Platzman, P. M.

J. T. Shen and P. M. Platzman, “Near field imaging with negative dielectric constant lenses,” Appl. Phys. Lett. 80(18), 3286–3288 (2002).
[Crossref]

Ramesh, R.

S. C. Kehr, P. Yu, Y. Liu, M. Parzefall, A. I. Khan, R. Jacob, M. T. Wenzel, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Microspectroscopy on perovskite-based superlens,” Opt. Mater. Express 1(5), 1051–1060 (2011).
[Crossref]

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

Schmidt, O. G.

M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
[Crossref] [PubMed]

Schneider, H.

M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
[Crossref] [PubMed]

Shalaev, V. M.

G. V. Naik, V. M. Shalaev, and A. Boltasseva, “Alternative plasmonic materials: beyond gold and silver,” Adv. Mater. 25(24), 3264–3294 (2013).
[Crossref] [PubMed]

G. V. Naik, J. Liu, A. V. Kildishev, V. M. Shalaev, and A. Boltasseva, “Demonstration of Al:ZnO as a plasmonic component for near-infrared metamaterials,” Proc. Natl. Acad. Sci. U.S.A. 109(23), 8834–8838 (2012).
[Crossref] [PubMed]

P. R. West, S. Ishii, G. V. Naik, N. K. Emani, V. M. Shalaev, and A. Boltasseva, “Searching for better plasmonic materials,” Laser Photonics Rev. 4(6), 795–808 (2010).
[Crossref]

Shen, J. T.

J. T. Shen and P. M. Platzman, “Near field imaging with negative dielectric constant lenses,” Appl. Phys. Lett. 80(18), 3286–3288 (2002).
[Crossref]

Shin, J.

M. Choi, S. H. Lee, Y. Kim, S. B. Kang, J. Shin, M. H. Kwak, K. Y. Kang, Y. H. Lee, N. Park, and B. Min, “A terahertz metamaterial with unnaturally high refractive index,” Nature 470(7334), 369–373 (2011).
[Crossref] [PubMed]

Shvets, G.

D. Korobkin, Y. Urzhumov, and G. Shvets, “Enhanced near-field resolution in midinfrared using metamaterials,” J. Opt. Soc. Am. B 23(3), 468–478 (2006).
[Crossref]

T. Taubner, D. Korobkin, Y. Urzhumov, G. Shvets, and R. Hillenbrand, “Near-field microscopy through a SiC superlens,” Science 313(5793), 1595 (2006).
[Crossref] [PubMed]

Smith, D. R.

D. R. Smith, J. B. Pendry, and M. C. K. Wiltshire, “Metamaterials and negative refractive index,” Science 305(5685), 788–792 (2004).
[Crossref] [PubMed]

Sun, C.

Z. Liu, H. Lee, Y. Xiong, C. Sun, and X. Zhang, “Far-field optical hyperlens magnifying sub-diffraction-limited objects,” Science 315(5819), 1686 (2007).
[Crossref] [PubMed]

N. Fang, H. Lee, C. Sun, and X. Zhang, “Sub-diffraction-limited optical imaging with a silver superlens,” Science 308(5721), 534–537 (2005).
[Crossref] [PubMed]

Sun, Y.

Y. Zhang, T. Wei, W. Dong, C. Huang, K. Zhang, Y. Sun, X. Chen, and N. Dai, “Near-perfect infrared absorption from dielectric multilayer of plasmonic aluminum-doped zinc oxide,” Appl. Phys. Lett. 102(21), 213117 (2013).
[Crossref] [PubMed]

Szabó, Z.

Taubner, T.

L. Jung, B. Hauer, P. Li, M. Bornhöfft, J. Mayer, and T. Taubner, “Exploring the detection limits of infrared near-field microscopy regarding small buried structures and pushing them by exploiting superlens-related effects,” Opt. Express 24(5), 4431–4441 (2016).
[Crossref]

P. Li, T. Wang, H. Böckmann, and T. Taubner, “Graphene-enhanced infrared near-field microscopy,” Nano Lett. 14(8), 4400–4405 (2014).
[Crossref] [PubMed]

P. Li and T. Taubner, “Broadband subwavelength imaging using a tunable graphene-lens,” ACS Nano 6(11), 10107–10114 (2012).
[Crossref] [PubMed]

T. Taubner, D. Korobkin, Y. Urzhumov, G. Shvets, and R. Hillenbrand, “Near-field microscopy through a SiC superlens,” Science 313(5793), 1595 (2006).
[Crossref] [PubMed]

Tung, S. K.

Y. C. Liu, J. H. Hsieh, and S. K. Tung, “Extraction of optical constants of zinc oxide thin films by ellipsometry with various models,” Thin Solid Films 510(1–2), 32–38 (2006).
[Crossref]

Urzhumov, Y.

T. Taubner, D. Korobkin, Y. Urzhumov, G. Shvets, and R. Hillenbrand, “Near-field microscopy through a SiC superlens,” Science 313(5793), 1595 (2006).
[Crossref] [PubMed]

D. Korobkin, Y. Urzhumov, and G. Shvets, “Enhanced near-field resolution in midinfrared using metamaterials,” J. Opt. Soc. Am. B 23(3), 468–478 (2006).
[Crossref]

von Ribbeck, H.-G.

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

S. C. Kehr, P. Yu, Y. Liu, M. Parzefall, A. I. Khan, R. Jacob, M. T. Wenzel, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Microspectroscopy on perovskite-based superlens,” Opt. Mater. Express 1(5), 1051–1060 (2011).
[Crossref]

Wang, T.

P. Li, T. Wang, H. Böckmann, and T. Taubner, “Graphene-enhanced infrared near-field microscopy,” Nano Lett. 14(8), 4400–4405 (2014).
[Crossref] [PubMed]

Wang, X.

A. Bisht, W. He, X. Wang, L. Y. L. Wu, X. Chen, and S. Li, “Hyperlensing at NIR frequencies using a hemispherical metallic nanowire lens in a sea-urchin geometry,” Nanoscale 8(20), 10669–10676 (2016).
[Crossref] [PubMed]

Wei, T.

Y. Zhang, T. Wei, W. Dong, C. Huang, K. Zhang, Y. Sun, X. Chen, and N. Dai, “Near-perfect infrared absorption from dielectric multilayer of plasmonic aluminum-doped zinc oxide,” Appl. Phys. Lett. 102(21), 213117 (2013).
[Crossref] [PubMed]

Wenzel, M. T.

S. C. Kehr, P. Yu, Y. Liu, M. Parzefall, A. I. Khan, R. Jacob, M. T. Wenzel, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Microspectroscopy on perovskite-based superlens,” Opt. Mater. Express 1(5), 1051–1060 (2011).
[Crossref]

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

West, P. R.

P. R. West, S. Ishii, G. V. Naik, N. K. Emani, V. M. Shalaev, and A. Boltasseva, “Searching for better plasmonic materials,” Laser Photonics Rev. 4(6), 795–808 (2010).
[Crossref]

Wiltshire, M. C. K.

D. R. Smith, J. B. Pendry, and M. C. K. Wiltshire, “Metamaterials and negative refractive index,” Science 305(5685), 788–792 (2004).
[Crossref] [PubMed]

Winnerl, S.

M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
[Crossref] [PubMed]

Wu, L. Y. L.

A. Bisht, W. He, X. Wang, L. Y. L. Wu, X. Chen, and S. Li, “Hyperlensing at NIR frequencies using a hemispherical metallic nanowire lens in a sea-urchin geometry,” Nanoscale 8(20), 10669–10676 (2016).
[Crossref] [PubMed]

Xiong, Y.

Z. Liu, H. Lee, Y. Xiong, C. Sun, and X. Zhang, “Far-field optical hyperlens magnifying sub-diffraction-limited objects,” Science 315(5819), 1686 (2007).
[Crossref] [PubMed]

Xu, J.

F. Liu, L. Cui, G. Lu, Y. Li, T. Yang, C. Xue, J. Xu, and G. Du, “Multiple and broadband near-perfect absorption in heterostructures containing transparent conducting oxides,” J. Appl. Phys. 119(8), 083106 (2016).
[Crossref]

Xue, C.

F. Liu, L. Cui, G. Lu, Y. Li, T. Yang, C. Xue, J. Xu, and G. Du, “Multiple and broadband near-perfect absorption in heterostructures containing transparent conducting oxides,” J. Appl. Phys. 119(8), 083106 (2016).
[Crossref]

Yang, C.-H.

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

Yang, S.-Y.

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

Yang, T.

F. Liu, L. Cui, G. Lu, Y. Li, T. Yang, C. Xue, J. Xu, and G. Du, “Multiple and broadband near-perfect absorption in heterostructures containing transparent conducting oxides,” J. Appl. Phys. 119(8), 083106 (2016).
[Crossref]

Yao, K.

M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
[Crossref] [PubMed]

Yoon, J.

J. Yoon, M. Zhou, M. A. Badsha, T. Y. Kim, Y. C. Jun, and C. K. Hwangbo, “Broadband epsilon-near-zero perfect absorption in the near-infrared,” Sci. Rep. 5, 12788 (2015).
[Crossref] [PubMed]

Yu, P.

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

S. C. Kehr, P. Yu, Y. Liu, M. Parzefall, A. I. Khan, R. Jacob, M. T. Wenzel, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Microspectroscopy on perovskite-based superlens,” Opt. Mater. Express 1(5), 1051–1060 (2011).
[Crossref]

Yun, I.

E. N. Cho, S. Park, and I. Yun, “Spectroscopic ellipsometry modeling of ZnO thin films with various O2 partial pressures,” Curr. Appl. Phys. 12(6), 1606–1610 (2012).
[Crossref]

Zhang, K.

Y. Zhang, T. Wei, W. Dong, C. Huang, K. Zhang, Y. Sun, X. Chen, and N. Dai, “Near-perfect infrared absorption from dielectric multilayer of plasmonic aluminum-doped zinc oxide,” Appl. Phys. Lett. 102(21), 213117 (2013).
[Crossref] [PubMed]

Zhang, X.

P. Cao, L. Cheng, X. Zhang, X. Huang, and H. Jiang, “Near-infrared plasmonic far-field nanofocusing effects with elongated depth of focus based on hybrid Au–dielectric–Ag subwavelength structures,” Plasmonics 11(5), 1219–1231 (2016).
[Crossref]

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling,” Nat. Commun. 2, 249 (2011).
[Crossref] [PubMed]

S. C. Kehr, P. Yu, Y. Liu, M. Parzefall, A. I. Khan, R. Jacob, M. T. Wenzel, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh, “Microspectroscopy on perovskite-based superlens,” Opt. Mater. Express 1(5), 1051–1060 (2011).
[Crossref]

Z. Liu, H. Lee, Y. Xiong, C. Sun, and X. Zhang, “Far-field optical hyperlens magnifying sub-diffraction-limited objects,” Science 315(5819), 1686 (2007).
[Crossref] [PubMed]

N. Fang, H. Lee, C. Sun, and X. Zhang, “Sub-diffraction-limited optical imaging with a silver superlens,” Science 308(5721), 534–537 (2005).
[Crossref] [PubMed]

Zhang, Y.

Y. Zhang, T. Wei, W. Dong, C. Huang, K. Zhang, Y. Sun, X. Chen, and N. Dai, “Near-perfect infrared absorption from dielectric multilayer of plasmonic aluminum-doped zinc oxide,” Appl. Phys. Lett. 102(21), 213117 (2013).
[Crossref] [PubMed]

Zhou, M.

J. Yoon, M. Zhou, M. A. Badsha, T. Y. Kim, Y. C. Jun, and C. K. Hwangbo, “Broadband epsilon-near-zero perfect absorption in the near-infrared,” Sci. Rep. 5, 12788 (2015).
[Crossref] [PubMed]

ACS Nano (1)

P. Li and T. Taubner, “Broadband subwavelength imaging using a tunable graphene-lens,” ACS Nano 6(11), 10107–10114 (2012).
[Crossref] [PubMed]

ACS Photonics (1)

S. C. Kehr, R. G. P. McQuaid, L. Ortmann, T. Kämpfe, F. Kuschewski, D. Lang, J. Döring, J. M. Gregg, and L. M. Eng, “A local superlens,” ACS Photonics 3(1), 20–26 (2016).
[Crossref]

Adv. Mater. (1)

G. V. Naik, V. M. Shalaev, and A. Boltasseva, “Alternative plasmonic materials: beyond gold and silver,” Adv. Mater. 25(24), 3264–3294 (2013).
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Y. Zhang, T. Wei, W. Dong, C. Huang, K. Zhang, Y. Sun, X. Chen, and N. Dai, “Near-perfect infrared absorption from dielectric multilayer of plasmonic aluminum-doped zinc oxide,” Appl. Phys. Lett. 102(21), 213117 (2013).
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E. N. Cho, S. Park, and I. Yun, “Spectroscopic ellipsometry modeling of ZnO thin films with various O2 partial pressures,” Curr. Appl. Phys. 12(6), 1606–1610 (2012).
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Laser Photonics Rev. (1)

P. R. West, S. Ishii, G. V. Naik, N. K. Emani, V. M. Shalaev, and A. Boltasseva, “Searching for better plasmonic materials,” Laser Photonics Rev. 4(6), 795–808 (2010).
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M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, and M. Helm, “Plasmonic superlensing in doped GaAs,” Nano Lett. 15(2), 1057–1061 (2015).
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Nanoscale (1)

A. Bisht, W. He, X. Wang, L. Y. L. Wu, X. Chen, and S. Li, “Hyperlensing at NIR frequencies using a hemispherical metallic nanowire lens in a sea-urchin geometry,” Nanoscale 8(20), 10669–10676 (2016).
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Nature (1)

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P. Cao, L. Cheng, X. Zhang, X. Huang, and H. Jiang, “Near-infrared plasmonic far-field nanofocusing effects with elongated depth of focus based on hybrid Au–dielectric–Ag subwavelength structures,” Plasmonics 11(5), 1219–1231 (2016).
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Proc. Natl. Acad. Sci. U.S.A. (1)

G. V. Naik, J. Liu, A. V. Kildishev, V. M. Shalaev, and A. Boltasseva, “Demonstration of Al:ZnO as a plasmonic component for near-infrared metamaterials,” Proc. Natl. Acad. Sci. U.S.A. 109(23), 8834–8838 (2012).
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J. Yoon, M. Zhou, M. A. Badsha, T. Y. Kim, Y. C. Jun, and C. K. Hwangbo, “Broadband epsilon-near-zero perfect absorption in the near-infrared,” Sci. Rep. 5, 12788 (2015).
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Y. C. Liu, J. H. Hsieh, and S. K. Tung, “Extraction of optical constants of zinc oxide thin films by ellipsometry with various models,” Thin Solid Films 510(1–2), 32–38 (2006).
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Figures (3)

Fig. 1
Fig. 1 Schematic illustration of two types of superlenses: (a) the ZnO-AZO-ZnO stratified superlens and (b) the single-layered AZO superlens. The gold double slits with various widths (w = 50 and 100 nm) and a fixed thickness of h = 10 nm were considered.
Fig. 2
Fig. 2 (a) Calculated real and imaginary parts of the permittivity of AZO and (b) real part of the permittivity of ZnO. (c) OTF of AZO without surrounding media as a function of the thickness d and the transverse wave vector k x at a wavelength of 2.57  μm . (d) OTF for two types of superlens structures at the resonant wavelengths, together with that in free space.
Fig. 3
Fig. 3 Amplitude distribution of x-component of electric field of the ZnO-AZO-ZnO stratified superlens imaging for the gold double silts with a width of (a) w = 100 nm and (b) w = 50 nm, and (c) their line profiles of energy density at image planes. In the case of the single-layered AZO superlens, the electric field distribution for (d) w = 100 nm, (e) w = 50 nm, and (f) the corresponding line profiles.

Equations (3)

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M j =[ cos δ j isin δ j / η j i η j sin δ j cos δ j ],
k jz = ε j ω 2 c 2 k x 2 ,
T= 2 η 0 A η 0 +B η 0 η N+1 +C+D η N+1 ,

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