The document discusses the design of a superlens using metamaterials that can focus light below the diffraction limit in the visible range. It summarizes previous research on superlenses and metamaterials. The authors then describe their simulation study of a superlens design using a silver metamaterial slab. Their results show that the design is able to enhance evanescent waves and potentially achieve subwavelength resolution.

1. DESIGN OF SUPERLENS IN THE VISIBLE RANGE USING
METAMATERIALS
Ahmed Aslam V.V and Srinivasa Rao U
1st
year M.Tech Nanotechnology
Centre for Nanotechnology Research /School of Electronics Engineering, VIT University,
Vellore-632014, Tamil Nadu, India
asluveeran@gmail.com, sreenivas869@gmail.com
Abstract
During last two decades there have been major advances in high resolution imaging using beyond
diffraction limit optics where the meta-materials are playing a dominant role. Use of meta-material
slabs can act as ideal lens without any aberrations and focus the evanescent waves for super high
resolution .
The paper addresses the simulation studies carried out on such meta-material lenses and the
theoretical models used to simulate the Super (ideal) lens.
1.0 Introduction
Lens makers have been dreaming of making a lens which produces images that are flawless. It is
observed that in conventional optics, diffraction limit is present. The small features of an object are
lost forever when the features are less than half the wavelength of light. So the information is lost,
since the light coming from the objects has components with large spatial frequencies which
exponentially decay because the waves are evanescent which cause a low resolution image. The
conventional lenses also due to various aberrations distort the image. The lost details are the mainly
due to diffraction limit. This decreases the resolution. Many have been trying make optics which work
beyond diffraction limit. [Reference 1]
Pendry proposed that a perfect lens could be made out of metamaterial. He
also said that using double negative medium evanescent waves could be amplified to attain sub
wavelength resolution. The increase in the number of layers and maintaining the same thickness will
affect the image. The losses due to the size effects will decrease the imaging process but it will never
degrade the superlens effect.[ Reference 2]

2. Superlens is made from crossed metal wires. In this model, the attenuation is
reduced. It is able to show the sub wavelength features. This model will allow the sub wavelength
modes to propagate and modes are enhanced. This model is similar to a superlens made of Silver. A
resolution of λ/8 is achieved. This will work in microwave and Terahertz regions.[Reference 3]
Superlens made of anisotropic metamaterials will work similar to Pendry’s
concept . It works on a lens formula by which it is able to decrease the thickness of metamaterial
slabs. Such can work over greater distance between the lens and the object. Thus a far field Superlens
in the visible range can be realised.[ Reference 4]
Superlens with 36nm silver and wavelength of 364nm is designed. A
resolution of λ/6 is attained. It is observed that to increase the resolution, the dielectric function of
outside medium should be greater than 1. The field strength should be higher on the top so that the
evanescent waves can be retained. [Reference 5]
2.0 Super Lens
Super lens is also known as a perfect lens where both ε and μ are negative ( ε>= -1 and μ>= -1) and
which use combination materials to give negative R.I or as metamaterials to go beyond the diffraction
limit. In conventional optical devices or lenses, diffraction limit is an inherent limitation.
When we observe various images through conventional lenses, sharpness
of the image is determined by various aberrations, the transmittance of light of specific wavelengths
which are limited by the diffraction of the various wavelengths through the lens system. In the year
2000, a slab of metamaterial having negative refractive index was theorized to create a lens having
better capabilities beyond conventional (positive index) lenses. A British scientist, Sir John Pendry,
proposed that a thin slab of negative metamaterial might overcome the problems with common lenses
to achieve a “perfect lens” that would focus entire spectrum, consisting both evanescent and
propagating spectra. A lens was proposed using a metal film as metamaterial. When illuminated near
its plasma frequency the lens could be used for super resolution imaging. In addition both evanescent
and propagating waves contribute to give high resolution of the image. Pendry suggested that left
handed slabs act as perfect imaging system if they are completely lossless, impedance matched and
their refractive index is n=-1 with respect to the surrounding medium. Theoretically, this was a
breakthrough in optical domain.

3. 2.1 Optical super lens with silver metamaterial
Fig 1 Plan view of the lens in operation
Pendry showed that the evanescent waves will be enhanced after they pass through a thin slab of
silver. Even though image with high resolution was not observed, the regeneration of the evanescent
waves was shown.
The lens will make a correction of the phase to the Fourier components. After some distance the field
will converge to a focus. For higher values of transverse wave vector, the evanescent waves will
decay and no correction in phase is applicable. So they get separated from image and it consists of
propagating waves only. However the resolution will not be greater than Δ = λ.
Materials having negative refractive index will focus light. A negative index medium will bend light
away from the normal. The light will reach focus from two regions. Both the dielectric constant and
permeability are negative.
i.e., ε = -1, μ= -1
The refractive index can be obtained as,
n = )
There is a reversal of the phase which allows the medium to focus light again. The evanescent waves
will decay only in amplitude. While focussing, there is no need to correct the phase. The enhancement
of the amplitude of evanescent waves will take place. Both the propagating and evanescent waves are
responsible for the image resolution.

4. Fig 2 A slab of negative-refractive-index medium acts as a perfect lens a) bringing all the
diverging rays from an object into a focused image b) enhancement of the evanescent waves,
evanescent waves amplitude are identical both at the object and image plane
We first use a positive index material followed by negative index material. It is followed by again a
positive index material. Then use a thin slab of silver of width 40 nm, as negative index material,
which will focus the image by maintaining the amplitude of higher order Fourier components. Light
(350nm) is incident at the top of first positive index slab.
Fig 3 Snapshot of the design simulation in Comsol

5. 3.0 Results and discussions
The design has been simulated in comsol multiphysics 4.2a. We first define the global parameters like
permittivity, angle of incidence, wavelength ,relative permeability, refractive index. Then we define
the geometry. Then we will choose the materials required in negative and positive index media. Next
we define the ports ,in port 1 light is incident and is the object plane and port 2 is the image plane. In
the port1, wave excitation is on and in port 2 it is off. Then we define the periodic and transition
boundary conditions. Next is the meshing part, a triangular mesh is used. Next we will compute for
the results. Finally the results are obtained and plots are observed.
Fig 4 Evanescent waves enhancement
Here we plot the Electric Field vs the length of the lens. We can see that in the first positive index
slab, evanescent waves decrease and in the following negative index slab, the evanescent waves are
increased. In the following positive index slab, evanescent waves decrease. So the image formed at
image plane will be same as that of object plane.
4.0 Conclusions
The foundation of superlensing theory—regeneration of evanescent waves by means of a metal film
—has been validated in our experiment. Although these experiments are conducted with pristine
silver films, the experimental configuration will provide a test bed for the artificially synthesized
metamaterials.

6. 5.0 Acknowledgement
First of all, I would like to thank the management for giving me such an opportunity. While preparing
the paper, I got basic ideas for creating a research paper. I would like to thank our faculties for
extended support. I would also like to thank our colleagues who were of great help.
6.0 Reference
1. “Negative Refraction Makes a Perfect Lens”: J. B. Pendry: Physical Review Letters, Volume 85,
Number 18 (2000)
2. “Composite near-field superlens design using mixing formulas and simulations”: Henrik Wallén ,
Henrik Kettunen, Ari Sihvola: Metamaterials 3 (2009) pp:129–139
3. “Superlens made of a metamaterial with extreme effective parameters”: Mário G. Silveirinha,
Carlos A. Fernandes and Jorge R.Costa: Physical Review B Volume 78, Issue 19 (2008)
4. “Compact planar far-field super lens based on anisotropic left-handed metamaterials”: Nian-Hai
Shen, Stavroula Foteinopoul, Maria Kafesaki, Thomas Koschny, Ekmel Ozbay, Eleftherios N.
Economou, and Costas M. Soukoulis: Physical Review B Volume 80 (2009)
5. “Imaging properties of a metamaterial superlens”: Nicholas Fang and Xiang Zhang: Applied
Physics Letters: Volume 82, Number 2 (2003)
6. “Negative refraction Metamaterials”: G.V. Eleftheriades and K. G. Balmain: John Wiley & Sons

7. 5.0 Acknowledgement
First of all, I would like to thank the management for giving me such an opportunity. While preparing
the paper, I got basic ideas for creating a research paper. I would like to thank our faculties for
extended support. I would also like to thank our colleagues who were of great help.
6.0 Reference
1. “Negative Refraction Makes a Perfect Lens”: J. B. Pendry: Physical Review Letters, Volume 85,
Number 18 (2000)
2. “Composite near-field superlens design using mixing formulas and simulations”: Henrik Wallén ,
Henrik Kettunen, Ari Sihvola: Metamaterials 3 (2009) pp:129–139
3. “Superlens made of a metamaterial with extreme effective parameters”: Mário G. Silveirinha,
Carlos A. Fernandes and Jorge R.Costa: Physical Review B Volume 78, Issue 19 (2008)
4. “Compact planar far-field super lens based on anisotropic left-handed metamaterials”: Nian-Hai
Shen, Stavroula Foteinopoul, Maria Kafesaki, Thomas Koschny, Ekmel Ozbay, Eleftherios N.
Economou, and Costas M. Soukoulis: Physical Review B Volume 80 (2009)
5. “Imaging properties of a metamaterial superlens”: Nicholas Fang and Xiang Zhang: Applied
Physics Letters: Volume 82, Number 2 (2003)
6. “Negative refraction Metamaterials”: G.V. Eleftheriades and K. G. Balmain: John Wiley & Sons