Three-Dimensional Subwavelength Imaging by a Photonic-Crystal Flat Lens Using Negative Refraction at Microwave Frequencies

Lu, Zhaolin; Murakowski, Janusz; Schuetz, Christopher A.; Shi, Shouyuan; Schneider, Garrett J.; Prather, Dennis W.

doi:10.1103/physrevlett.95.153901

Cited by 108 publications

(39 citation statements)

References 17 publications

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“…Metal-based NIMs [3][4][5][6][7][8][9][10][11] have been actively studied because of their unusual physical properties and their potential for use in many technological applications [12][13][14][15][16][17][18][19][20][21][22] ; however, they usually have the disadvantage of demonstrating large optical losses in their metallic components. As an alternative to metal-based NIMs, dielectricbased photonic crystals (PhCs) have been investigated and shown to emulate the basic physical properties of NIMs [23][24][25][26][27] , while also having relatively small absorption losses at optical frequencies. Equally important, PhCs can be nanofabricated within current silicon foundries, suggesting significant potential for the development of future electronic-photonic integrated circuits.…”

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confidence: 99%

Zero phase delay in negative-refractive-index photonic crystal superlattices

et al. 2011

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We show that optical beams propagating in path-averaged zero-index photonic crystal superlattices can have zero phase delay. The nanofabricated superlattices consist of alternating stacks of negative index photonic crystals and positive index homogeneous dielectric media, where the phase differences corresponding to consecutive primary unit cells are measured with integrated Mach-Zehnder interferometers. These measurements demonstrate that at path-averaged zero-index frequencies the phase accumulation remains constant and equal to zero despite the increase in the physical path length. We further demonstrate experimentally that these superlattice zero-n bandgaps remain invariant to geometrical changes of the photonic structure and have a center frequency which is deterministically tunable. The properties of the zero-n gap frequencies, optical phase, and effective refractive indices are well described by detailed experimental measurements, rigorous theoretical analysis, and comprehensive numerical simulations.A n intense degree of interest in negative-index metamaterials (NIMs) 1,2 has developed in recent years. Metal-based NIMs 3-11 have been actively studied because of their unusual physical properties and their potential for use in many technological applications [12][13][14][15][16][17][18][19][20][21][22] ; however, they usually have the disadvantage of demonstrating large optical losses in their metallic components. As an alternative to metal-based NIMs, dielectricbased photonic crystals (PhCs) have been investigated and shown to emulate the basic physical properties of NIMs [23][24][25][26][27] , while also having relatively small absorption losses at optical frequencies. Equally important, PhCs can be nanofabricated within current silicon foundries, suggesting significant potential for the development of future electronic-photonic integrated circuits.One particular type of PhC can be obtained by cascading alternating layers of NIMs and positive-index materials (PIMs) [28][29][30][31][32] . This photonic structure ( Fig. 1) has unique optical properties, including new surface states and gap solitons 33,34 , unusual transmission and emission properties [35][36][37][38][39] , complete photonic bandgaps 40 , and a phase-invariant field for cloaking applications 41 . Moreover, these binary photonic structures have an omnidirectional bandgap that is insensitive to wave polarization, incidence angle, structure periodicity and structural disorder [42][43][44] . Such a gap exists because the path-averaged refractive index is equal to zero within a certain frequency band [28][29][30][31][32]35 . At this frequency, the Bragg condition, kL ¼ (nv/c)L ¼ mp, is satisfied for m ¼ 0, irrespective of the period L of the superlattice (k and v are the wave vector and frequency, respectively, and n is the averaged refractive index). Because of this property this photonic bandgap is called zero-n, or zero-order bandgap 30,35 .Near-zero-index materials have a series of exciting potential applications, such as beam self-coll...

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confidence: 99%

Zero phase delay in negative-refractive-index photonic crystal superlattices

et al. 2011

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“…It is clear that the dispersion regime will show only the divergence effect for lower angle incident rays. (In case, if the flat lens is based on all angle negative refraction, then the PC slab will show the imaging effect even for a small slit source [27].). On the other hand, if the slit separation is very large, all sort of incident angles are impinged on the PC slab and one would clearly see the well-defined image spot as in Figure 5(b).…”

Section: Formation and Evolution Of Image's Spot Sizementioning

confidence: 99%

Near Field Focusing Effect and Hyperbolic Dispersion in Dielectric Photonic Crystals

Yogesh¹,

Subramanian²

2011

PIER M

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Abstract-This paper investigates the near field focusing behavior corresponding to the hyperbolic dispersion regime at the second band of the square lattice photonic crystal (PC). Numerical studies reveal the influence of the corner part negative refraction in the observed focusing effect, though the major part of the refraction is divergent at this hyperbolic regime. It is further observed that the investigated dispersion shows the surface mode behavior when the effective index of the PC slab is higher than the air medium. This aspect may be implemented for the excitation and transfer of near fields for an evanescent wave microscopy. OBJECTIVE OF THE PROBLEMThe concept of flat lens focusing proposed by Veselago [1], Silin [2], and Pendry [3] can be realized from three possible electromagnetic media. Namely, the metamaterial [4,5], photonic crystal [6], and an indefinite medium (whose permittivity and permeability tensors do not have same sign) [7][8][9][10]. The mechanism of flat lens imaging is accounted from negative refraction, in which a flat slab can be able to focus near fields with sub-wavelength features.However, for a photonic crystal, the concept of flat lens imaging is not only addressed from negative refraction [11] but also from other approaches such as an anisotropic effect [12], partial band gaps [13][14][15], diffractive effects [16], the role of reflection [17], the effect of channeling from self-collimation [18,19] and on the existence of surface modes [20] etc..With respect to the existing approaches, this work attempts to understand the near field focusing behavior (Figure 1) at the operating

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“…Thus, multiple reflections at the PhC slab sides have to be taken into account since they can have influence on the quality of the image, which is mainly characterised by its spatial width and its amplitude. It has to be mentioned that subwavelength imaging in the microwave regime has been experimentally demonstrated for both 2D [29] and three-dimensional PhCs [30]. In this work we carry out a thorough analysis of the imaging properties of a 2D PhC properly engineered to display an effective refractive index n=-1 at a certain frequency.…”

Section: Introductionmentioning

confidence: 99%