Zero-Index Bound States in the Continuum

Abstract

Metamaterials with an effective zero refractive index associated to their electromagnetic response are sought for a number of applications in communications and nonlinear optics. A promising way that this can be achieved in all-dielectric photonic crystals is through the design of a Dirac cone at zero Bloch wave-vector in the photonic band structure. In the optical frequency range, the natural way to implement this design is through the use of a photonic crystal slab. In the existing implementation, however, the zero-index photonic modes also radiate strongly into the environment due to intrinsic symmetry properties. This has resulted in large losses in recent experimental realizations of this zero-index paradigm. Here, we propose a photonic crystal slab with zero-index modes which are also symmetry-protected bound states in the continuum. Our approach thus eliminates the associated radiation loss. This could enable, for the first time, large-scale integration of zero-index materials in photonic devices.

Bound states in the continuum of higher-order topological insulators

“…Yet, in principle, spectral isolation is not necessary for the existence of localized bound states. In fact, bound states that coexist with degenerate extended ones, commonly known as bound states in the continuum (BICs), have been found across a variety of other physical systems, including quantum systems [30][31][32][33], water waves [34][35][36][37][38][39], acoustics [40][41][42][43][44][45], and photonics [46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64].…”

Multiple embedded eigenstates in nonlocal plasmonic nanostructures

“…Over the last decade, it was shown that optical bound states with suppressed radiation loss may exist within the radiation continuum in open resonators [12][13][14][15][16][17][18][19][20][21][22]. These excitations are known as "embedded eigenstates", in analogy with the spatially localized electron states with "positive energy" in quantum systems [23][24][25].…”

Total phase shift of terahertz wave in a rectangular waveguide with zero-refractive index metamaterial

“…One of the useful techniques to realize the phase shifters is using Photonic Crystal (PC) metamaterials. It is represented that PC metamaterials can tune the photonic dispersion so that one can build new optical devices with new functionalities [3,4,8,[10][11][12][13][14][15][16][17]. In fact, PC metamaterials could be built in a way which exhibit Dirac-cone photonic dispersion in the center of Brillouin-Zone in an arbitrary frequency using the concept of accidental degeneracy [15].…”