Introduction to optics of materials with negative refraction

Understanding the NIMs

Our NIM publications

Press about our work

Materials with negative index of refraction

In these projects we study the fundamental electromagnetic properties of a new class of materials - negative index of refraction media (NIMs). Our research is directed towards the design and development of practical NIMs, utilizing these unique systems to manipulate light with increasing accuracy and speed, and understanding the limitations of these systems even before we can build them.

Why study the NIMs? First and foremost, these materials are unique in a number of ways. Thus, they literary reverse some of the well-known fundamentals of modern optics. It is interesting to see how something as solid as law of refraction - which has been tested throughout the centuries of use in the design of telescopes, microscopes, binoculars, or even reading glasses - has to be modified in order to correctly explain the behavior of a new structure. Some other phenomena, as Doppler effect (used in Police "speed radars"), have to be rewritten as well. To see how unusual pulse propagation through NIM can be, and to read about history of NIMs, please visit this page.

Another motivation to study the NIMs is the unstoppable quest for the "faster, better, smaller" sensors, processors, cameras, and communication devices. Today, most of the processing work is done by silicon-based electronics. However, as the processing frequencies increase beyond some GHz, so does the power consumption - and the increasing amount of energy goes to heating - not to information processing. Light, on the other hand, has the frequency of 10⁶ (one million) GHz - and may in principle blow all today's electronics away. There are some problems with it though - the light pulse is much "larger" than the electron, and it's really hard to make two light pulses to talk to each other - a necessary step to make a processor. NIMs may provide the solutions to these problems, and in a sense, fuel our future progress.

One of the potential applications of NIMs is the so-called superlens, when the parallel slab of NIM is used to achieve the resolution exceeding the one of the best today's imaging systems. Here you can find the Java applet illustrating the superlens action.

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• NIM basics
• Studying the resolution limit of NIM-based planar lens
• Designing the optimal configuration of a superlens
• Design of new non-magnetic NIMs
• Sub-diffraction light localization and propagation with NIMs; slow and fast light

1. V.A. Podolskiy, N.A. Kuhta, G.W. Milton, "Optimizing the superlens: manipulating geometry to enhance the resolution" - Appl. Phys. Lett v.87 p.231113 (2005); arXiv:physics/0509067; (c) 2005 AIP
   [pdf/ url/press release/ arXiv/ abstract]
   Abstract:
   We analyze the performance of a planar lens based on realistic negative index material in a generalized geometry. We demonstrate that the conventional superlens design (where the lens is centered between the object and the image) is not optimal from the resolution point-of-view, develop an analytical expression for the resolution limit of a generalized lens, use it to find the optimum lens configuration, and calculate the maximum absorption practical nearfield superlenses may have. We demonstrate that in contrast to the conventional superlens picture, planar imaging is typically accompanied by excitation of surface waves at both interfaces of the lens.
2. R. Wangberg, J. Elser, E.E. Narimanov, and V.A. Podolskiy, "Non-magnetic nano-composites for optical and infrared negative refraction index media" - accepted to JOSA B; arXiv:physics/0506196
   [ arXiv/ abstract]
   Abstract:
   We develop an approach to use nanostructured plasmonic materials as a non-magnetic negative-refractive index system at optical and near-infrared frequencies. In contrast to conventional negative refraction materials, our design does not require periodicity and thus is highly tolerant to fabrication defects. Moreover, since the proposed materials are intrinsically non-magnetic, their performance is not limited to proximity of a resonance so that the resulting structure has relatively low loss. We develop the analytical description of the relevant electromagnetic phenomena and justify our analytic results via numerical solutions of Maxwell equations.
3. G. Milton, N.-A. Nicorovici, R. McPhedran, and V. Podolskiy, "A proof of superlensing in the quasistatic regime, and limitations of superlenses in this regime due to anomalous localized resonance" - Proc. Roy. Soc. Lond. A 461 p.3999 (2005)
   [url/ abstract ]
   Abstract:
   Enlarging upon work of Nicorovici, McPhedran, and Milton (1994) a rigorous proof is given that in the quasistatic regime a cylindrical superlens can successfully image a dipolar line source in the limit as the loss in the lens tends to zero. In this limit it is proved that the field blows up to infinity in two sometimes overlap- ping annular anomalously locally resonant regions, one of which extends inside the lens and the other of which extends outside the lens. If the object being imaged responds to an applied field it is argued that it must lie outside the resonant re- gions to be successfully imaged. If the image is being probed it is argued that the resonant regions created by the probe should not interfere with either the probe itself or the object being imaged, if that object responds to an applied field. Per- fect imaging in a cylindrical superlens is shown to extend to the static equations of magnetoelectricity or thermoelectricity provided they have a special structure which makes these equations equivalent to the quasistatic equations.
4. V.A. Podolskiy, L. Alekseyev, and E.E. Narimanov "Strongly anisotropic media: the THz perspectives of left-handed materials", J. Mod. Opt. 52(16) p. 2343 (2005); arXiv:physics/0505024
   [ pdf/ arXiv/ abstract ]
   Abstract:
   We demonstrate that non-magnetic m=1 left-handed materials can be effectively used for waveguide imaging systems. We also propose a specific THz realization of the non-magnetic left-handed material based on homogeneous, naturally-occurring media.
5. V.A. Podolskiy and E.E. Narimanov "Strongly anisotropic waveguide as a nonmagnetic left-handed system" - Phys. Rev. B, 71 201101(R) (2005); arXiv:physics/0405077
   [ pdf/ arXiv / abstract ]
   Abstract:
   We develop an approach to build a material with negative refraction index that can be implemented for optical and infrared frequencies. In contrast to conventional designs that require simultaneously negative dielectric permittivity and magnetic permeability and rely on a resonance to achieve a nonzero magnetic response, our material is intrinsically nonmagnetic and makes use of an anisotropic dielectric constant to provide a lefthanded behavior in waveguide geometry. We demonstrate that the proposed material can support surface (polariton) waves, and show the connection between the polaritons and the enhancement of evanescent fields, also known as superlensing.
6. V.A. Podolskiy, A.K. Sarychev, E.E. Narimanov, and V.M. Shalaev "Resonant light interaction with plasmonic nanowire systems" - J. Optics A: Pure. Appl. Opt 7, S32 (2005); arXiv:physics/0406068;
   [ pdf/ arXiv / abstract ]

   Abstract:
   We compare the optical response of isolated nanowires, double-wire systems, and Pi-structures, and show that their radiation is well described in terms of their electric and magnetic dipole moments. We also show that both dielectric permittivity and magnetic permeability can be negative at optical and near infrared frequencies, and demonstrate the connection between the geometry of the system and its resonance characteristics. We conclude that plasmonic nanowires can be employed for developing novel negative-index materials. Finally, we demonstrate that it is possible to construct a nanowire-based "transparent nanoresonator&" with dramatically enhanced intensity and metal concentration below 5%

7. V.A. Podolskiy and E.E. Narimanov "Near-sighted superlens" - Optics Letters 30, 75 (2005); arXiv:physics/0403139
   [ pdf/abstract ]

   Abstract:
   The materials with simultaneously negative dielectric permittivity and magnetic permeability also known as left-handed materials (LHMs), are among the most rapid-developing topics in the modern scientific community due to their exciting and often unnatural electromagnetic properties. The ``ultimate application'' of LHM is the construction of a lens with ``perfect'' (subwavelength) optical resolution in the far field, which -- although potentially leading to a tremendous advance in imaging, fabrication, and communications -- have initiated a lot of controversy. In the present work we show that the LHM-based lens ceases to be perfect in the presence of even a small absorption and the area of its subwavelength resolution is usually limited to the proximity of the scatterer, similarly to well-developed near-field optics. We derive the relation between the focal distance and resolution of the superlens, and resolve the above mentioned controversy

8. V.A. Podolskiy, A.K. Sarychev and V.M. Shalaev “Plasmon modes and negative refraction in metal nanowire composites” – Optics Express 11 735 (2003)
   [ pdf / abstract ]

   Abstract:
   Optical properties of metal nanowires and nanowire composite materials are studied. An incident electromagnetic wave can effectively couple to the propagating surface plasmon polariton (SPP) modes in metal nanowires resulting in very large local fields. The excited SPP modes depend on the structure of nanowires and their orientation with respect to incident radiation. A nanowire percolation composite is shown to have a broadband spectrum of localized plasmon modes. We also show that a composite of nanowires arranged into parallel pairs can act as a left-handed material with the effective magnetic permeability and dielectric permittivity both negative in the visible and near-infrared spectral ranges.

9. V.A. Podolskiy, A.K Sarychev, and V.M. Shalaev “Plasmon Modes in Metal Nanowires” JNOPM, 11 vol. 1, 65 (2002).
   [ pdf / erratum-pdf / abstract ]

   Abstract:
   The electromagnetic field distribution for thin metal nanowires is found, by using the discrete dipole approximation. The plasmon polariton modes in wires are numerically simulated. These modes are found to be dependent on the incident light wavelength and direction of propagation. The existence of localized plasmon modes and strong local field enhancement in percolation nanowire composites is demonstrated. Novel left-handed materials in the near-infrared and visible are proposed based on nanowire composites.

1. V.A. Podolskiy, E.E. Narimanov "Nanostructured non-magnetic left-handed composites" - in AP-S/URSI 2005 proceedings (IEEE, Washington DC 2005), 0-7803-8883-6/05
   [pdf]
2. V.A. Podolskiy, E.E. Narimanov "Nanoplasmonic approach to strongly anisotropic optical materials"- in CLEO/QELS/PhAST 2005 (OSA, Washington DC 2005), JThC3
   [pdf]
3. V.A. Podolskiy, E.E. Narimanov "Non-magnetic left-handed composite" in CLEO/QELS/PhAST 2005 (OSA, Washington DC 2005), JThE103
   [pdf]
4. L. Alekseev, V.A. Podolskiy, E.E. Narimanov "THz non-magnetic negative refraction system" – in CLEO/QELS/PhAST 2005 (OSA, Washington DC 2005), JThC2
   [pdf]
5. V.A. Podolskiy, A.K. Sarychev, E.E. Narimanov, and V.M. Shalaev “Light manipulation with plasmonic nanoantennas” – proceedings of IEEE AP-S/URSI conference 0-7803-8302-8, (June 2004)
   [pdf]
6. A.K. Sarychev, V.A. Podolskiy, and V.M. Shalaev “Optical properties of plasmonic nanowires: surface plasmon modes and negative refraction”, PIERS (2003)

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