Valley‐Hall Photonic Topological Insulators with Dual‐Band Kink States

Abstract

Extensive researches have revealed that valley, a binary degree of freedom (DOF), can be an excellent candidate of information carrier. Recently, valley DOF is introduced into photonic systems, and several valley‐Hall photonic topological insulators (PTIs) are experimentally demonstrated. However, in the previous valley‐Hall PTIs, topological kink states only work at a single frequency band, which limits potential applications in multiband waveguides, filters, communications, and so on. To overcome this challenge, here a valley‐Hall PTI, where the topological kink states exist at two separated frequency bands, is experimentally demonstrated in a microwave substrate‐integrated circuitry. Both the simulated and experimental results demonstrate the dual‐band valley‐Hall topological kink states are robust against the sharp bends of the internal domain wall with negligible intervalley scattering. This work may pave the way for multichannel substrate‐integrated photonic devices with high efficiency and high capacity for information communications and processing.

Recent advances in 2D, 3D and higher-order topological photonics

“…In this case, is broken by differentiating the heights of the two sublattices of the honeycomb lattice. The quantum valley Hall effect has been confirmed numerically by using dielectric rods in a perturbed kagome lattice 62 and experimentally by using coupled waveguide arrays with detuned refractive indices 63 , a dielectric slab with air holes with a -breaking shape 64 , 65 and -broken connected dielectrics that have dual-band edge states 66 . The quantum valley Hall phase can also be implemented in an active system.…”

Manipulating topological valley modes in plasmonic metasurfaces

“…Previous plasmonic topological valley systems have solely focused on single band effects, but such a dual band structure allows topological valley states to exist in two frequency regimes. Dual band effects have also been demonstrated in photonic crystals [46] and acoustics [47].…”

Local orbital-angular-momentum dependent surface states with topological protection

“…In this work, we present chiral edge states that are supported at the zigzag edge of a single valley PC in contact with air, which is very different from previous studies where edge states are supported at the interface separating two valley PCs symmetrical to each other under inversion [16][17][18][19][20][21][22][23]. The edge states we considered are well localized at the edge sites and evanescent both inside and outside the valley PC, and hence become surface states.…”

“…Valley-dependent edge states have been observed at the interface of two valley PCs with interchanged r A and r B [17,19] and one valley PC but with an external cladding [20]. In the following, we will demonstrate the cladding-free guidance of valley-dependent edge states.…”

“…the quantum valley Hall (QVH) effect. Correspondingly, the electromagnetic (EM) version of the valley degree of freedom has also been studied [16][17][18][19][20][21][22][23].…”