Fig. 1. Honeycomb plasmonic nanocone array and its spectral properties. (a) SEM image showing the NCA from top and profile views (the inset), illustrating the real-space configuration of the arrays. (b) Reciprocal-space representation of the 2D honeycomb lattice arrays, with the inset depicting the first Brillouin zone of the hexagonal lattice, marked by the six lowest orders of reciprocal lattice vectors (white arrows). Here ky (pink arrows) represents the in-plane wavevector k propagating along the y direction and kDO (blue arrows) denotes the wavevectors of the diffraction orders. (c) Experimental angle-resolved reflection dispersion along the Γ−K direction for Al NCA, measured from incident angle from 10° to 50° under white light source. The DOs are calculated using the ELA method, shown as white dashed line. (d) Reflection spectra of the NCA as the incident angles increase from 20° to 40°, alongside the perovskite emission (indicated by gray line).

Fig. 2. Characterization of the perovskite-coated NCA. (a) SEM image of the NCA with perovskite in top and profile views (inset), with the perovskite area artificially colored for clarity. (b) Photograph of the NCA with perovskite under ambient lighting (left) and ultraviolet light (right, illuminated by a UV flashlight). (c) Simulated electric field distribution of the NCA on the x−z plane at a 30° incident angle and 520 nm wavelength, conducted via FDTD simulation. (d) Experimental angle-resolved reflection dispersion along the Γ−K direction, measured under white light. (e) Reflection spectra of the coupled system under the angle from 20° to 40°, alongside the emission of the quasi-2D perovskite (gray dotted line), with arrows marking the shift of the reflection dips. (f) Schematic diagram of energy splitting between the SLR and quantum emitter modes, forming upper and lower polaritons separated by Rabi splitting.

Fig. 3. Ultrafast dynamics analysis of the hybrid system via TA measurement and CQED calculation. (a) Evolution of the TA spectra of the quasi-2D perovskite-coated NCA at 30°, along with that of the Al flat substrate (inset) with delay times of 0.5, 10, 25, 50, and 100 ps. (b) Dynamics of the UP/LP states (yellow/green point lines) and the state of the perovskite before coupling (gray line) as a function of relaxation time from 0 to 500 ps. Evolution of the TA spectra of the perovskite-coated NCA at (c) 20° and (d) 40°. The excitation wavelength remains 435 nm for the entire TA measurement. (e) Calculated proportions of the SLR (green line) and quantum emitter (yellow line) modes in UP and LP as a function of incident angles from 20° to 40°. (f) Calculated temporal evolution of SLR (green line) and quantum emitter (yellow line) modes within UP and LP subsystems from 0 to 100 fs. Double-sided arrows indicate the frequency of the Rabi oscillation (2π/ω).

Fig. 4. (a)–(c) Calculated dispersions of honeycomb lattice with different periods, ranging from 300 to 600 nm, theoretically plotted by ELA (along the direction of Γ−K).

Fig. 5. Characterization of the perovskite. (a) SEM image of the perovskite on Al flat in top view. (b) Absorption (gray line) and photoluminescence (green line) spectra of the perovskite on glass substrate.

Fig. 6. Simulated electric field distribution of the NCA on the x−y plane at a 30° incident angle and 520 nm wavelength, conducted by FDTD simulation.