Topological photonic crystals: a review

Abstract

Photonic topological phases offering unprecedented manipulation of electromagnetic waves have attracted much research interest which, however, have been mostly restricted to a single band gap. Here, we report on the experimental discovery of hybrid topological photonic crystals which host simultaneously quantum anomalous Hall and valley Hall phases in different photonic band gaps. The underlying hybrid topological phase manifests itself in the edge responses as the coexistence of the chiral edge states and valley Hall edge states in different frequency ranges. We experimentally verify such an emergent phenomenon and show that such a feature enables novel multiplexing of photon transport in the edge channels. Our study reveals a situation with coexisting topology of distinct nature in a single photonic system that may enable frequency-dependent filtering and manipulation of topological edge photons.

Slow Light Rainbow Trapping in a Uniformly Magnetized Gyromagnetic Photonic Crystal Waveguide

“…The recent realization of topological photonic insulators has been an emerging research area, which has brought the discovery of topological photonic states (TPSs) (Khanikaev et al, 2013;Lu et al, 2014;Lu et al, 2016;Khanikaev and Shvets, 2017;Xie et al, 2018;Ozawa et al, 2019;Tang et al, 2019;Kim et al, 2020;Wang et al, 2020;Chen et al, 2021a). TPSs possess the one-way transport characteristic and are robust against the sharp corner, disorders, defects, and obstacles, which induces promising applications such as the non-reciprocal devices for photonic diode and robust waveguides for light routing.…”

Rapid Screening of Butyl Paraben Additive in Toner Sample by Molecularly Imprinted Photonic Crystal

“…PC is composed of several kinds of the regular shaped materials which have different dielectric constants and are periodically arranged in the PC skeleton [26][27][28]. Owing to the existence of photonic band gap in the PCs, only the light with certain wavelengths can be reflected from their surfaces, resulting in the characteristic structural colors of the PCs [29][30][31]. Any slight change of the lattice constant of the PC skeleton caused by the stimuli, such as the acidity, temperature, humidity, ionic strength as well as the concentration/speciation variations of the chemicals, will result in the shift of the Bragg reflection peak.…”

Ideal type-II Weyl points in twisted one-dimensional dielectric photonic crystals

“…Specifially, Dirac/Weyl semimetals have been demonstrated to exhibit several peculiar phenomena, such as Fermi arcs and chiral anomaly [1,11], while for type-II Weyl points, the unique features including tilted cone dispersion and the surface states existed in an incomplete bandgap would bring more exotic effects [10]. In classical systems, the analogues of various topological semimetals have also been achieved in photonics [12][13][14][15][16][17][18][19][20][21][22][23][24][25], acoustics [26][27][28][29][30][31],circuits [32] and magnetic systems [33,34]. Type-I Weyl points and the arc surface states have been theoretically [12] and experimentally [13,14,27] verified in 3D photonic/phononic crystals and metamaterials, and also been found recently that the Weyl semimetals can sustain higher-order topological hinge states [35][36][37][38].…”