High‐order exceptional points and enhanced sensing in subwavelength resonator arrays

Abstract

Systems exhibiting degeneracies known as exceptional points have remarkable properties with powerful applications, particularly in sensor design. These degeneracies are formed when eigenstates coincide, and the remarkable effects are exaggerated by increasing the order of the exceptional point (i.e., the number of coincident eigenstates). In this work, we use asymptotic techniques to study scriptPT‐symmetric arrays of many subwavelength resonators and search for high‐order asymptotic exceptional points. This analysis reveals the range of different configurations that can give rise to such exceptional points and provides efficient techniques to compute them. We also show how systems exhibiting high‐order exceptional points can be used for sensitivity enhancement.

Non-reciprocal wave propagation in space-time modulated media

“…Our results in this paper can be of immense importance for the mathematical foundation of other non-reciprocal guiding phenomena such as the valley Hall effect [16,23,25,26,32,48] and the skin effect [33,44,49]. The valley Hall effect may occur in truncated honeycomb lattices of time-modulated subwavelength resonators by opening non-reciprocal band gaps at Dirac points [6,12] while the skin effect may be obtained by opening non-reciprocal band gaps at exceptional points associated with the unmodulated structure [3,4,14]. These two challenging topics will be the subject of forthcoming publications.…”

“…Here, the subwavelength nature stems from a high material contrast between the constituting materials of the structure. Such structures can be used to achieve a variety of effects [1,[3][4][5][6][7][8][9]12]. Of particular importance for us are systems of time dependent high-contrast resonators.…”

Robustness of subwavelength devices: a case study of cochlea-inspired rainbow sensors

“…Figure 7: We study the effects of removing resonators from a cochlea-inspired rainbow sensor. (a) The rainbow sensor with a single resonator removed, denoted D (5) . (b) The rainbow sensor with multiple resonators removed, denoted D (2,5,8,9) .…”

Scattering resonances for a three-dimensional subwavelength hole

“…The readers are referred to [7,11,12,[18][19][20][21][22][23][24][25]29] for the detailed investigation of different resonant phenomena for several typical subwavelength structures. Other related mathematical studies on the subwavelength resonant wave scattering and their applications can be found in [2][3][4][5] and references therein. In this work, we consider the three-dimensional problem and present quantitative analysis of scattering resonances for the acoustic wave scattering by a subwavelength hole embedded in a sound hard slab.…”