Multiple slow waves and relevant transverse transmission and confinement in chirped photonic crystals

Abstract

Abstract:The dispersion properties of rod-type chirped photonic crystals (PhCs) and non-channeled transmission in the direction of the variation of structural parameters from one cell of such a PhC to another are studied. Two types of configurations that enable multiple slow waves but differ in the utilized chirping scheme are compared. It is demonstrated that the multiple, nearly flat bands with a group index of refraction exceeding 180 can be obtained. For these bands, transmission is characterized by multiple narrow peaks of perfect transmission, strong field enhancement inside the slab, and large values of the Q-factor. Among the bands, there are some that show negative phase velocity. Symmetry with respect to the slab mid-plane must be kept in order to obtain constructive interferences that are necessary for reflection-free transmission. It is shown that 15 and more slow wave bands can be obtained in one configuration. The corresponding transmission peaks are well separated from each other, being the only significant feature of the transmission spectrum, while the Q-factor can exceed 10 5 . The observed features are preserved in a wide range of the incidence angle variation. They can be used for tuning the locations and spectral widths of the transmission peaks. Some comparisons with the chirped multilayer structures have been carried out.

Focusing, Imaging and Fourier Transforming With a Large Numerical Aperture, Dielectric Flat Photonic Crystal Lens in Metamaterial Regime

“…When ∆z=1.05λ, β value ranges between 0.4 and 0.43 based on Eq. (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) for different ray trajectories depicted in Fig. 4(a).…”

“…On the other hand, while still being volumetric, dielectric based Graded Index Photonic Crystals (GRIN PCs) have been proposed in order to build lenses that would be immune to non-idealities stemming from parasitic losses and resonator configurations [15,16]. Since then the GRIN PCs have been efficiently shown to guide the light carefully to serve as waveguide input couplers [17], to slow down the light [18] and to achieve self-collimation, super-bending and mirage effects [19][20][21][22]. The main ideas have been borrowed from the already well-established GRIN optics as the lattice configurations have been carefully adjusted to mimic GRIN media [23].…”

Single–Band and Multiband Angular Filtering Using Two–Dimensional Photonic Crystals and One–Layer Gratings

“…It can also be achieved in PhC slabs that represent 3D structures, in which height of the rods or holes is comparable with lattice constant [21]. They may appear owing to Floquet-Bloch modes in the entirely periodic structures [19,20], defect modes arising due to structural defects [12], and pure supercell modes, e.g., in non-uniform PhCs with parameters that are gradually varying from one unit cell to another [22]. All these structures and modes have potential in angular filtering.…”

Focusing of light beyond the diffraction limit by randomly distributed graded index photonic medium

“…3 In addition to PCs, aperiodically ordered or disordered photonic structures have attracted great attention because of their intriguing optical characteristics. [4][5][6] Aperiodic and disordered structures compared to periodic structures can provide additional flexibilities and properties for engineering the optical response of the designed devices. The study of light propagation in random media has become a very popular area of research in recent decades.…”