Hybrid topological guiding mechanisms for photonic crystal fibers

Abstract

We create hybrid topological-photonic localisation of light by introducing concepts from the field of topological matter to that of photonic crystal fiber arrays. S-polarized obliquely propagating electromagnetic waves are guided by hexagonal, and square, lattice topological systems along an array of infinitely conducting fibers. The theory utilises perfectly periodic arrays that, in frequency space, have gapped Dirac cones producing band gaps demarcated by pronounced valleys locally imbued with a nonzero local topological quantity. These broken symmetry-induced stop-bands allow for localised guidance of electromagnetic edge-waves along the crystal fiber axis. Finite element simulations, complemented by asymptotic techniques, demonstrate the effectiveness of the proposed designs for localising energy in finite arrays in a robust manner.

A Short Review of All-Dielectric Topological Photonic Crystals

“…For applications, many intriguing photonic devices, including energy beam splitters [127,131,132,135], logic gates [127], switches [132], fiber [134], and filter [132] are created via PVHIs [131,132]. Based on valley edge states, the electrically pumped terahertz quantum cascade laser is also realized [128].…”

A brief review of topological photonics in one, two, and three dimensions

“…Valley edge modes have also been studied in plasmonic systems, e.g., in surface-wave photonic crystal on a single metal surface [184], designer surface plasmon crystal comprising metallic patterns deposited on a dielectric substrate [185], graphene plasmonic crystals [186][187][188][189], metal nanoparticles [190] and metal cylinders [191]. Valley edge modes have found a range of interesting applications, such as, lasing [192][193][194][195][196], fiber [197,198], reconfigurable devices [199][200][201], slow light [202][203][204][205], chiral coupling to quantum emitters [206][207][208], Mach-Zehnder interferometer [209], on-chip quantum information processing [210], long-range deformations [211], and logic gates [212]. Especially, for topological lasing based on valley edge modes, recently, an electrically pumped terahertz quantum cascade laser was experimentally demonstrated in a triangular lattice of quasi-hexagonal holes drilled through the active medium of a terahertz quantum cascade laser wafer [192] (see Fig.…”

Topological supermodes in photonic crystal fiber

“…For example, arrays of silicon waveguides are limited by scattering loss in the near infrared (20), whereas for visible light, state-of-the-art planar fabrication techniques, such as using lasers to inscribe waveguides into a glass chip, are challenging to extend beyond the centimeter scale (21). Optical fiber that supports topological modes has previously been proposed (22)(23)(24)(25)(26), but experimental demonstrations have not been seen because of the impossibility of fabricating previous designs with current technology.…”