Related Publications
Savo, Salvatore; Casse, BDF; Lu, Wentao; Sridhar, Srinivas Observation of slow-light in a metamaterials waveguide at microwave frequencies Journal Article In: Applied Physics Letters, vol. 98, no. 17, pp. 171907, 2011. Casse, BDF; Lu, WT; Huang, YJ; Gultepe, E; Menon, L; Sridhar, S Super-resolution imaging using a three-dimensional metamaterials nanolens Journal Article In: Applied Physics Letters, vol. 96, no. 2, pp. 023114, 2010. Lu, WT; Huang, YJ; Casse, BDF; Banyal, RK; Sridhar, S Storing light in active optical waveguides with single-negative materials Journal Article In: Applied Physics Letters, vol. 96, no. 21, pp. 211112, 2010. Lu, WT; Sridhar, S Slow light, open cavity formation, and large longitudinal electric field on slab waveguide made of indefinite-index metamaterials Journal Article In: arXiv preprint arXiv:0902.4482, 2009. Lu, WT; Sridhar, S Superlens imaging theory for anisotropic nanostructured metamaterials with broadband all-angle negative refraction Journal Article In: Physical Review B, vol. 77, no. 23, pp. 233101, 2008. Huang, YJ; Lu, WT; Sridhar, S Nanowire waveguide made from extremely anisotropic metamaterials Journal Article In: Physical Review A, vol. 77, no. 6, pp. 063836, 2008. Casse, BDF; Lu, WT; Huang, YJ; Sridhar, S Nano-optical microlens with ultrashort focal length using negative refraction Journal Article In: Applied Physics Letters, vol. 93, no. 5, pp. 053111, 2008. Casse, Bernard Didier F; Banyal, Ravinder K; Lu, WT; Huang, YJ; Selvarasah, Selvapraba; Dokmeci, M; Sridhar, Srinivas Nanoengineering of a negative-index binary-staircase lens for the optics regime Journal Article In: Applied Physics Letters, vol. 92, no. 24, pp. 243122, 2008. Lu, WT; Huang, YJ; Vodo, P; Banyal, RK; Perry, CH; Sridhar, S A new mechanism for negative refraction and focusing using selective diffraction from surface corrugation Journal Article In: Optics express, vol. 15, no. 15, pp. 9166–9175, 2007. Huang, YJ; Lu, WT; Sridhar, S New approach to all-angle-negative-refraction in two-dimensional photonic crystals Journal Article In: APS, pp. S38–002, 2007. Lu, Wentao; Vodo, P; Sridhar, Srinivas Negative Refraction in Photonic Crystals Book Section In: Physics of Negative Refraction and Negative Index Materials, pp. 133–147, Springer, Berlin, Heidelberg, 2007. Vodo, P; Lu, WT; Huang, Y; Sridhar, S Negative refraction and plano-concave lens focusing in one-dimensional photonic crystals Journal Article In: Applied physics letters, vol. 89, no. 8, pp. 084104, 2006. Vodo, Plarenta; Parimi, PV; Lu, WT; Sridhar, Srinivas Focusing by planoconcave lens using negative refraction Journal Article In: Applied Physics Letters, vol. 86, no. 20, pp. 201108, 2005. Lu, Wentao T; Sridhar, Srinivas Flat lens without optical axis: Theory of imaging Journal Article In: Optics express, vol. 13, no. 26, pp. 10673–10680, 2005. Gennaro, E Di; Parimi, PV; Lu, WT; Sridhar, S; Derov, JS; Turchinetz, B Slow microwaves in left-handed materials Journal Article In: Physical Review B, vol. 72, no. 3, pp. 033110, 2005.@article{savo2011observation,
title = {Observation of slow-light in a metamaterials waveguide at microwave frequencies},
author = {Salvatore Savo and BDF Casse and Wentao Lu and Srinivas Sridhar},
year = {2011},
date = {2011-01-01},
journal = {Applied Physics Letters},
volume = {98},
number = {17},
pages = {171907},
publisher = {American Institute of Physics},
abstract = {We report an experimental observation of slow-light in the GHz microwave regime utilizing the mechanism of the degeneracy of forward and backward waves in a planar waveguide consisting of a dielectric core cladded by single-negative metamaterial.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{casse2010super,
title = {Super-resolution imaging using a three-dimensional metamaterials nanolens},
author = {BDF Casse and WT Lu and YJ Huang and E Gultepe and L Menon and S Sridhar},
year = {2010},
date = {2010-01-01},
journal = {Applied Physics Letters},
volume = {96},
number = {2},
pages = {023114},
publisher = {American Institute of Physics},
abstract = {Super-resolution imaging beyond Abbe’s diffraction limit can be achieved by utilizing an optical medium or “metamaterial” that can either amplify or transport the decaying near-field evanescent waves that carry subwavelength features of objects. Earlier approaches at optical frequencies mostly utilized the amplification of evanescent waves in thin metallic films or metal-dielectric multilayers, but were restricted to very small thicknesses (⪡λ, wavelength) and accordingly short object-image distances, due to losses in the material. Here, we present an experimental demonstration of super-resolution imaging by a low-loss three-dimensional metamaterial nanolens consisting of aligned gold nanowires embedded in a porous alumina matrix. This composite medium possesses strongly anisotropic optical properties with negative permittivity in the nanowire axis direction, which enables the transport of both far-field and near-field components with low-loss over significant distances (>6λ), and over a broad spectral range. We demonstrate the imaging of large objects, having subwavelength features, with a resolution of at least λ/4 at near-infrared wavelengths. The results are in good agreement with a theoretical model of wave propagation in anisotropic media.
The authors would like to thank M. G. Silveirinha, D. Heiman, J. Sokoloff, and F. Camino for useful discussions and comments. This work was financially supported by the Air Force Research Laboratories, Hanscom through Grant No. FA8718-06-C-0045 and NSF through Grant No. PHY-0457002. The work was also performed in part at the Kostas Center at Northeastern University and the Center for Nanoscale Systems, a member of NNIN, which is supported by the National Science Foundation under NSF Award No. ECS-0335765. Research carried out in part at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886.},
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pubstate = {published},
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}
The authors would like to thank M. G. Silveirinha, D. Heiman, J. Sokoloff, and F. Camino for useful discussions and comments. This work was financially supported by the Air Force Research Laboratories, Hanscom through Grant No. FA8718-06-C-0045 and NSF through Grant No. PHY-0457002. The work was also performed in part at the Kostas Center at Northeastern University and the Center for Nanoscale Systems, a member of NNIN, which is supported by the National Science Foundation under NSF Award No. ECS-0335765. Research carried out in part at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886.@article{lu2010storing,
title = {Storing light in active optical waveguides with single-negative materials},
author = {WT Lu and YJ Huang and BDF Casse and RK Banyal and S Sridhar},
year = {2010},
date = {2010-01-01},
journal = {Applied Physics Letters},
volume = {96},
number = {21},
pages = {211112},
publisher = {American Institute of Physics},
abstract = {We show that a nonresonant planar waveguide consisting of conventional dielectric cladded with single-negative materials supports degenerate propagating modes for which the group velocity and total energy flow can be zero if the media are lossless. Absorptive losses will destroy the zero-group velocity condition for real frequency/complex wave vector modes.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{lu2009slowb,
title = {Slow light, open cavity formation, and large longitudinal electric field on slab waveguide made of indefinite-index metamaterials},
author = {WT Lu and S Sridhar},
year = {2009},
date = {2009-01-01},
journal = {arXiv preprint arXiv:0902.4482},
abstract = {There is a strong interest in slow light structures and devices [1–10]. This is driven by the need for optical buffers and optical memory in optical integrated circuits and other applications. In order to have small group velocity, various methods have been exploited to engineer material and structural dispersions, such as electromagnetic induced transparency [11], coupled resonant structures [5, 12], and optical nonlinearity [3]. Tsakmakidis et al [6] proposed a new scheme to realize trapped rainbow by using negative-index metamaterials. This slow light waveguide requires its core layer to be made of double negative metamaterial (DNM) whose permittivity and permeability are both negative. It is quite a challenge to realize DNMs with very low loss [13] since even moderate loss will destroy the zero group velocity mode [14, 15]. Strictly speaking, when loss is present as is inevitable in passive systems, stop light is impossible. However, gain may be introduced to compensate loss and makes zero group velocity possible [16]. In this paper we consider planar waveguide made of the so-called indefinite-index media [17–20] whose permittivity and/or the permeability tensors are indefinite matrices. For an indefinite-index metamaterial (IIM), the dispersion is hyperbolic for one polarization and elliptical for the other. Negative refraction, superlens imaging, and hyperlens focusing [21, 22] can be realized by using IIMs. Nanowire waveguide made of IIM has been considered by Huang et al [23]. These indefinite-index waveguides can support both forward-and backwardwave modes. High phase index can be obtained for these guided modes. These waveguides …},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{lu2008superlens,
title = {Superlens imaging theory for anisotropic nanostructured metamaterials with broadband all-angle negative refraction},
author = {WT Lu and S Sridhar},
year = {2008},
date = {2008-01-01},
journal = {Physical Review B},
volume = {77},
number = {23},
pages = {233101},
publisher = {APS},
abstract = {We show that a metamaterial consisting of aligned metallic nanowires in a dielectric matrix has strongly anisotropic optical properties. For long wavelngths, the longitudinal SPR, the material exhibits positive transverse permittivity and negative longitudinal permittivity, relative to the nanowires axis, enabling the achievement of broadband all-angle negative refraction and superlens imaging. An imaging theory of superlens made of these media is established. High performance systems made with Au, Ag, or Al nanowires in nanoporous templates are designed and predicted to work from the infrared up to ultraviolet frequencies.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{huang2008nanowire,
title = {Nanowire waveguide made from extremely anisotropic metamaterials},
author = {YJ Huang and WT Lu and S Sridhar},
year = {2008},
date = {2008-01-01},
journal = {Physical Review A},
volume = {77},
number = {6},
pages = {063836},
publisher = {APS},
abstract = {Exact solutions are obtained for all the modes of wave propagation along an anisotropic cylindrical waveguide. Closed-form expressions for the energy flow on the waveguide are also derived. For extremely anisotropic waveguide where the transverse permittivity is negative while the longitudinal permittivity is positive, only transverse magnetic (TM) and hybrid modes will propagate on the waveguide. At any given frequency the waveguide supports an infinite number of eigenmodes. Among the TM modes, at most only one mode is forward wave. The rest of them are backward waves which can have very large effective index. At a critical radius, the waveguide supports degenerate forward- and backward-wave modes with zero group velocity. These waveguides can be used as phase shifters and filters, and as optical buffers to slow down and trap light.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{casse2008nano,
title = {Nano-optical microlens with ultrashort focal length using negative refraction},
author = {BDF Casse and WT Lu and YJ Huang and S Sridhar},
year = {2008},
date = {2008-01-01},
journal = {Applied Physics Letters},
volume = {93},
number = {5},
pages = {053111},
publisher = {American Institute of Physics},
abstract = {We have experimentally realized an ultrashort focal length planoconcave microlens in an InP/InGaAsP semiconductor two-dimensional photonic crystal with negative index of refraction n = -0.7. At wavelength 1.5 microns, the lens exhibits ultrashort focal lengths of 12 microns (~ 8x wanelength) and numerical aperture close to unity. The focused beam has a near diffraction-limited spot size of 1.05 microns (~ 0.68 wavelength) at full width at half maximum. The negative refractive index and focusing properties of the microlens are confirmed by 2D finite-difference time-domain simulations. Such ultrarefractive negative-index nano-optical microlenses can be integrated into existing emiconductor heterostructure platforms for next-generation optoelectronic applications.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{casse2008nanoengineering,
title = {Nanoengineering of a negative-index binary-staircase lens for the optics regime},
author = {Bernard Didier F Casse and Ravinder K Banyal and WT Lu and YJ Huang and Selvapraba Selvarasah and M Dokmeci and Srinivas Sridhar},
year = {2008},
date = {2008-01-01},
journal = {Applied Physics Letters},
volume = {92},
number = {24},
pages = {243122},
publisher = {American Institute of Physics},
abstract = {We show that a binary-staircase optical element can be engineered to exhibit an effective negative index of refraction, thereby expanding the range of optical properties theoretically available for future optoelectronic devices. The mechanism for achieving a negative-index lens is based on exploiting the periodicity of the surface corrugation. By designing and nanofabricating a planoconcave binary-staircase lens in the InP/InGaAsP platform, we have experimentally demonstrated at 1.55 micrometers that such negative-index concave lenses can focus plane waves. The beam propagation in the lens was studied experimentally and was in excellent agreement with the three-dimensional finite-difference time-domain numerical simulations.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{lu2007new,
title = {A new mechanism for negative refraction and focusing using selective diffraction from surface corrugation},
author = {WT Lu and YJ Huang and P Vodo and RK Banyal and CH Perry and S Sridhar},
year = {2007},
date = {2007-01-01},
journal = {Optics express},
volume = {15},
number = {15},
pages = {9166--9175},
publisher = {Optical Society of America},
abstract = {Refraction at a smooth interface is accompanied by momentum transfer normal to the interface. We show that corrugating an initially smooth, totally reflecting, non-metallic interface provides a momentum kick parallel to the surface, which can be used to refract light negatively or positively. This new mechanism of negative refraction is demonstrated by visible light and microwave experiments on grisms (grating-prisms). Single-beam all-angle-negative-refraction is achieved by incorporating a surface grating on a flat multilayered material. This negative refraction mechanism is used to create a new optical device, a grating lens. A planoconcave grating lens is demonstrated to focus plane microwaves to a point image. These results show that customized surface engineering can be usedto achieve negative refraction even though the bulk material has positive refractive index. The surface periodicity provides a tunable parameter to control beam propagation leading to novel optical and microwave devices.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{huang2007new,
title = {New approach to all-angle-negative-refraction in two-dimensional photonic crystals},
author = {YJ Huang and WT Lu and S Sridhar},
year = {2007},
date = {2007-01-01},
journal = {APS},
pages = {S38--002},
abstract = {We show that with an appropriate surface modification, a slab of photonic crystal can be made to allow wave transmission within the photonic band gap. Furthermore, negative refraction and all-angle negative refraction _AANR_ can be achieved by this surface modification in frequency windows that were not realized before in two-dimensional photonic crystals _C. Luo et al., Phys. Rev. B 65, 201104 _2002__. This approach to AANR leads to different applications in flat lens imaging. Previous flat lens using photonic crystals requires object-image distance u + v less than or equal to the lens thickness d, u + v = σd. Our approach can be used to design a flat lens with large σ, thus being able to image large and/or far away objects. Our results are confirmed by finite-difference time-domain simulations.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@incollection{lu2007negative,
title = {Negative Refraction in Photonic Crystals},
author = {Wentao Lu and P Vodo and Srinivas Sridhar},
year = {2007},
date = {2007-01-01},
booktitle = {Physics of Negative Refraction and Negative Index Materials},
pages = {133--147},
publisher = {Springer, Berlin, Heidelberg},
abstract = {An intriguing property of the left-handed material is negative refraction. The optical properties of materials that are transparent to electromagnetic (EM) waves can be characterized by an index of refraction. Given the direction of the incident beam at the interface of vacuum and the material, the direction of the outgoing beam can be determined using Snell’s formula. All naturally available materials possess a positive refractive index. In lefthanded materials EM waves bend negatively and consequently a negative index of refractive index can be assigned to such materials without violating Maxwell’s equations. This negative bending allows considerable control over light propagation and opens the door for new approaches to a variety of applications from microwave to optical frequencies. We have demonstrated neagative refraction by a metallic photonic crystal.
},
keywords = {},
pubstate = {published},
tppubtype = {incollection}
}
@article{vodo2006negative,
title = {Negative refraction and plano-concave lens focusing in one-dimensional photonic crystals},
author = {P Vodo and WT Lu and Y Huang and S Sridhar},
year = {2006},
date = {2006-01-01},
journal = {Applied physics letters},
volume = {89},
number = {8},
pages = {084104},
publisher = {American Institute of Physics},
abstract = {Negative refraction is demonstrated in one-dimensional _1D_ dielectric photonic crystals _PCs_ at microwave frequencies. Focusing by plano-concave lens made of 1D PCs due to negative refraction is also demonstrated. The frequency-dependent negative refractive indices, calculated from the experimental data, match very well with those determined from band structure calculations. The easy fabrication of one-dimensional photonic crystals may open the door for future applications.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{vodo2005focusing,
title = {Focusing by planoconcave lens using negative refraction},
author = {Plarenta Vodo and PV Parimi and WT Lu and Srinivas Sridhar},
year = {2005},
date = {2005-01-01},
journal = {Applied Physics Letters},
volume = {86},
number = {20},
pages = {201108},
publisher = {American Institute of Physics},
abstract = {We demonstrate focusing of a plane microwave by a planoconcave lens fabricated from a photonic crystal having a negative refractive index and left-handed electromagnetic properties. An inverse experiment, in which a plane wave is produced from a source placed at the focal point of the lens, is also reported. A frequency-dependent negative refractive index, n(ω) < 0 is obtained for the lens from the experimental data which match well with that determined from band structure calculations.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{lu2005flat,
title = {Flat lens without optical axis: Theory of imaging},
author = {Wentao T Lu and Srinivas Sridhar},
year = {2005},
date = {2005-01-01},
journal = {Optics express},
volume = {13},
number = {26},
pages = {10673--10680},
publisher = {Optical Society of America},
abstract = {We derive a general theory for imaging by a flat lens without optical axis. We show that the condition for imaging requires a material having elliptic dispersion relations with negative group refraction. This medium is characterized by two intrinsic parameters σ and κ. Imaging can be achieved with both negative and positive wave vector refraction if σ is a positive constant. The Veselago-Pendry lens is a special case with σ = 1 and κ = 0. A general law of refraction for anisotropic media is revealed. Realizations of the imaging conditions using anisotropic media and inhomogeneous media, particularly photonic crystals, are discussed. Numerical examples of imaging and requirements for sub-wavelength imaging are also presented.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@article{di2005slow,
title = {Slow microwaves in left-handed materials},
author = {E Di Gennaro and PV Parimi and WT Lu and S Sridhar and JS Derov and B Turchinetz},
year = {2005},
date = {2005-01-01},
journal = {Physical Review B},
volume = {72},
number = {3},
pages = {033110},
publisher = {APS},
abstract = {Remarkably slow propagation of microwaves in two different classes of left-handed materials LHM�s is reported from microwave-pulse and continuous-wave transmission measurements. Microwave dispersion in a composite LHM made of split-ring resonators and wire strips reveals group velocity vg ~ c/50, where c is the free-space light velocity. Photonic crystals PhCs made of dielectric Al2O3 rods reveal vg ~ c/10. Group delay dispersion of both the composite LHM and PhCs determined from the experiment is in complete agreement with that obtained from theory. The slow group velocities are quantitatively described by the strong dispersion observed in these materials.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
