Zero phase delay induced by wavefront modulation in photonic crystals

Abstract

A new mechanism for generation of efficient zero phase delay of electromagnetic wave propagation based on wavefront modulation is investigated in this paper. Both numerical simulations and experiment have demonstrated the zero phase delay behaviors of wave propagation in a two-dimensional triangular photonic crystal. The zero phase delay propagation, independent of the propagating distance, is attributed to an invariable wavefront modulation of photonic crystal in the direction of wave propagation, where the phase velocity is perpendicular to the group velocity with parallel wavefronts (or phasefronts) extending along the direction of energy flow. This effect can be extended to the three-dimensional cases or other artificially engineered materials, and may open a new route to obtain perfect zero-phase-delay propagation for electromagnetic wave instead of using zero-index or zero-averaged-index materials and have significant potential in many applications.Recently, great efforts have been made to construct materials with zero or near-zero-n with quasi-uniform phase and infinite wavelength [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Zero-n materials have a series of exciting potential applications, such as wavefront reshaping [10], beam self-collimation [5,13], extremely convergent lenses [17], etc. One of their most important applications is the optical links in lumped nanophotonic circuits that can guide light over hundreds of wavelengths without introducing phase variations so as to reduce the unwanted effects of frequency dispersion. Several different strategies have been applied to realize the zero-n material (or zero permittivity ε). One of them was to use metallic metamaterial structures with effective permittivity and/or permeability near zero [7,8]. Usually these materials suffer from strong resonance loss and hence the greatly deteriorated transmission efficiency. Alternative approaches include the microwave waveguides below cutoff [9], the combination of negative-and positive-index materials [13] or the periodic superlattice formed by alternating strips of positive index homogeneous dielectric media and negative index photonic crystals (PhCs) [18] with zero phase accumulation of a wave travelling through the whole superlattice. However, all these configurations require high fabrication precision and complicated architecture. Therefore, it is preferred to find an efficient and simpler way to achieve zero phase delay propagation of electromagnetic wave (EMW).Wavefront modulation supplies a novel method to realize equal phase

Lattice invisibility effect based on transverse Kerker scattering in 1D metalattices

“…The artificial ENZ metamaterials, including 1D multilayers [38], well-designed fishnet nanostructures [39] and metal resonators [40], may inevitably complicate the fabrication process and suffer from intrinsic Ohmic loss. As for photonic crystals with generated Dirac cone [21], high fabrication resolution is required and the characteristic size of structures are relatively large. However, in terms of lattice invisibility effects studied herein, the basic principle is merely based on resonant patterns of metaatoms in lattices, which not only offers more flexibility to engineer propagation behavior of electromagnetic waves but also makes it possible to realize such invisibility effects in sub-wavelength scale using simpler configurations.…”

“…In practice, these novel properties can be employed to design zerophase delay waveguides [17], high-efficiency electromagnetic cloaking [18] and low-loss nanophotonic circuits [19], etc. Conventionally, the realization of zero-phase transport relies on zero-index metamaterials [20] or photonic crystals with degenerated Dirac cone [21], which more or less inevitably complicates architectures and is more demanding for fabrication resolutions. Alternatively, by taking advantage of lattice invisibility effect, it is promising to achieve free phase function with unitary efficiency based on low-loss resonant nanostructures [22].…”

Anomalous Transmission Properties Modulated by Photonic Crystal Bands

“…Recently, materials with zero or near-zero-n has attracted great focus for the characteristics of uniform phase and infinite wavelength [47][48][49][50]. A series of exciting potential applications have been found in zero-n materials, such as wavefront reshaping [51], beam self-collimation [52], extremely convergent lenses [53], etc.…”

Zero phase delay in metamaterials

“…2011 年 Huang X Q 小组利用等效介质理论 [39] 运用随机简并, 设计出一种在 k=0 位置具有狄拉克锥 的正方晶格光子晶体, 将其映射为一个()=()=0 的系统 [40] . 磁波的波前进行调控来实现零相移传输 [41] . [42] ; 第三种情况, 即 Sk=0 通常不容易 http://engine.scichina.com/doi/10.1360/SSPMA2013-00081…”