Photonic Dirac cavities with spatially varying mass term

Abstract

In recent years, photonics has proven itself as an excellent platform for emulation of relativistic phenomena. Here, we show an example of relativistic-like trapping in photonic system that realizes Dirac-like dispersion with spatially inhomogeneous mass term. The modes trapped by such cavities, their energy levels, and corresponding orbitals are then characterized through optical imaging in real and momentum space. The fabricated cavities host a hierarchy of photonic modes with distinct radiation profiles directly analogous to various atomic orbitals endowed with unique characteristics, such as pseudo-particle-hall symmetry and spin degeneracy, and they carry topological charge which gives rise to radiative profiles with angular momentum. We demonstrate that these modes can be directionally excited by pseudo-spin–polarized boundary states. In addition to the fundamental interest in the structure of these pseudo-relativistic orbitals, the proposed system offers a route for designing new types of nanophotonic devices, spin-full resonators and topological light sources compatible with integrated photonics platforms.

Topological photonics: robustness and beyond

“…The ability to generate different Hamiltonians spanned by synthetic DoF also brings additional possibilities for mode engineering, giving rise to other topological modes, such as cavity and vortex states, which offer other exciting features for photonic applications, including the generation of vortex beams 21 , resilient multiplexing platforms, and new types of vertically emitting lasers 22 . We believe that further expanding effective Hamiltonians, for instance by coupling to intrinsic DoFs of matter or by leveraging synthetic dimensions, may open even richer physics and more exciting topological phenomena with inherently multi-physics discoveries in which topological photonic phases can be imparted to a wide range of phenomena.…”

Topological phononic metamaterials

“…The Dirac vortex, as mentioned in section 3.7, manifesting the vortex texture of the phase of the two-dimensional Dirac mass term, was extensively explored recently in metamaterials, based on honeycomb lattices with Kekulé-distortion [491,492]. The Majorana-like zero modes bound at vortices were observed in acoustic [217], mechanical [216,493], photonic [494,495] systems and were proposed to enhance laser performance [496][497][498][499][500][501].…”

Nonuniform pseudo-magnetic fields in photonic crystals

“…[14][15][16][17][18][19][20][21] Different from the perpendicular PMF generated by the shift of Dirac points, many works have been discovered that show the various in-plane PMFs can be obtained by spatially varying mass terms. This synthetic gauge field has been utilized to trap the photonic modes in the photonic Dirac cavity guide, 24,25 guide the topological modes in the Dirac waveguide, 26,27 and particularly realize the chiral LLs. 28 Graphene applied a nonuniform perpendicular magnetic or PMF possesses peculiar properties, such as snake state [29][30][31][32][33][34][35] and quantum confinement.…”