Strong coupling of Fabry-Pérot cavity mode, anapole, and exciton supported by an optical cavity with heterogeneous nano-optical metasurfaces

Carefully designed metasurfaces can serve as effective platforms for strong coupling phenomena by the excitation of specific modes and the enhancement of light-matter interactions. However, strong coupling simultaneously involving Fabry-Pérot (FP) cavity modes, anapole states, and excitons has not been thoroughly explored. In this work, we numerically present the strong coupling of a FP cavity-anapole-exciton supported by a nano-optical metasurface of bulk $\mathrm{W}{\mathrm{S}}_2$-Si heterogeneous nanodisks inserted into a FP optical cavity. The excited multiorder FP cavity modes enable giant Rabi splittings with tunable population due to all generated odd-order FP cavity modes strongly coupling with the anapole state and exciton of bulk $\mathrm{W}{\mathrm{S}}_2$-Si heterogeneous nanodisks. Giant Rabi splittings of 643 and 335 meV are, respectively, achieved by the first-order FP and third-order FP cavity-anapole-exciton interactions. Our designed hybrid system provides a robust platform for exploring ultrahigh Rabi splittings and strong coupling of multiple optical responses in light-matter interactions.

Figure 1

Schematic diagram of the hybrid system with a nano-optical metasurface of $\mathrm{W}{\mathrm{S}}_2$-Si heterogeneous nanodisks embedded in the FP cavity and the molecular structure of bulk $\mathrm{W}{\mathrm{S}}_2$.

Figure 2

(a) Transmission contour map of heterogeneous nanodisks with $H$. (b) Electromagnetic field distributions for the transmission dip at $T_1$. (c) Scattering power of ED and TD moments and transmission spectrum of metasurface with $H$ = 10 nm. (d) Normalized phases of ED and TD moments and their phase difference versus wavelength.

Figure 3

(a) Absorption contour map of anapole-exciton hybrid states as a function of $H$. Inset: heterogeneous nanodisk. (b) Absorption spectrum of heterogeneous nanodisks with $H=10$ nm. (c) Hybrid polariton branches calculated using FEM and CMT. (d) Hopfield coefficients for UP and LP polariton states contributed by anapole and exciton as a function of $H$.

Figure 4

(a) Absorption spectrum of pure FP cavity versus $L$. (b) Absorption spectrum of hybrid system versus $L$. (c) Electric field distribution of ${\mathrm{FP}}^1, {\mathrm{FP}}^2$, and ${\mathrm{FP}}^3$ cavity modes excited at different cavity lengths.

Figure 5

(a) Absorption spectrum of the hybrid system with $f_0=0$. The black dashed line is the absorption peak wavelength of pure ${\mathrm{FP}}^3$ cavity mode as $L$ changes. (b) Absorption spectrum of the ${\mathrm{FP}}^3$ cavity mode-anapole-exciton hybrid states as a function of $L$. Inset: unit cell. (c). Absorption spectrum of the hybrid system with $L$ = 520 nm. Normalized electric field distributions of (d), (e) upper and lower branches at zero-detuning point of FP cavity-anapole strong coupling; (f) exciton response of pure bulk $\mathrm{W}{\mathrm{S}}_2$; and (g)–(i) UP, LP, and MP branches at zero-detuning point of FP cavity-anapole-exciton strong coupling.

Figure 6

(a) Hybrid polariton branches calculated using FEM and CMT. (b) Hopfield coefficients for UP, MP, and LP contributed by ${\mathrm{FP}}^3$ cavity mode, anapole, and exciton as a function of $L$.

Figure 7

(a) Absorption contour map of the hybrid system with $f_0=1.5$ (40 nm ≤ $L$ ≤ 640 nm). (b) Variation trends of ${\mathrm{FP}}^1$ and ${\mathrm{FP}}^3$ cavity-anapole-exciton coupling induced Rabi splittings versus $f_0$.