The total internal reflection ellipsometry (TIRE) method was used for the excitation and study of the strong coupling between a Tamm plasmon polariton (TPP) and a surface plasmon polariton (SPP) in nanophotonic structures with 1D photonic crystals (PCs) and a gold nano-bumps lattice array on the top. Recent studies have shown that lattice of gold nano-bumps induced the generation of an additional Bragg mode, related with the lattice period which is not involved in the strong coupling of the hybrid TPP–SPP polaritonic mode. The detailed analysis has shown that the propagation length of the SPP increased, while the TPP decreased, due to the formation of an additional Bragg mode. The optical dispersion and propagation features of plasmons in 1D PCs with a uniform gold layer and the lattice of gold nano-bumps array were analysed by two coupled oscillator models and by wave vector vs. energy broadening. For the nanostructures with a uniform gold layer, the evaluated propagation length was δ_SPP ≈ 5.5–6.5 μm and δ_TPP ≈ 6.5–9.5 μm for SPP and TPP components in the hybrid polaritonic mode, respectively. Meanwhile, the changes induced by the periodic gold surface lattice resulted in a longer propagation length for the SPP component, where δ_SPPlattice ≈ 7–10.5 μm, and a decreasing length for TPP, where δ_TPPlattice ≈ 5.5–8.5 μm. The obtained results demonstrate a novel approach to control and change the propagation length under the strong coupling regime between TPP and SPP components in the hybrid plasmonic mode by using surface lattice arrays. The fabricated nanophotonic–plasmonic structures show the potential impact of direct laser writing (DLW) as a cost-effective, fast and large area coverage method for creating integrated photonic devices with designed properties, in this case changing the propagation length and coherence properties in the hybrid plasmonic mode. The application of surface lattice resonances together with the strong coupling regime leads to decreasing losses, resulting in the increasing propagation length and improved coherence properties of such plasmonic excitations, which, in turn, promises advanced properties for low electrical consumption or thresholdless plasmonic-based coherent emission nano-sources.

In this study, the sensitivity to the refractive index changes of the ambient was studied on the uniform gold film (~50 nm) with a 1D photonic crystal (PC) from periodic five TiO₂ (~110 nm)/SiO₂ (~200 nm) bilayers and gold nano-bumps array produced by direct laser writing on the same sample. The optical signal sensitivity of hybrid plasmonic resonances was compared with traditional surface plasmon resonance (SPR) on a single gold layer. The influence of the strong coupling regime between Tamm plasmon polariton (TPP) and propagated plasmon polaritons in the hybrid plasmonic modes on the sensitivity of the optical was discussed. Recent studies have shown very high hybrid plasmonic mode sensitivity S_HSPP ≈ 26,000 nm/RIU to the refractive index on the uniform gold layer; meanwhile, the introduction of gold lattice reduces the signal sensitivity, but increases the Q-factor of the plasmonic resonances. Despite this, the sensitivity to the ellipsometric parameters Ψ and Δ on the gold lattice was rather high due to the increased Q-factor of the resonances. The comparison of plasmonic resonance sensitivity to the refractive index changes of hybrid TPP-SPP mode on the uniform gold layer and traditional SPR have shown that hybrid plasmonic mode, due to a strong coupling effect, overcomes the SPR by about 27%.

Strong light–matter interactions have received a lot of attention, for example in the pursuit of plasmonic‐excitonic structures as coherent light sources with low‐power threshold. In this study, we investigate the influence of room temperature strong coupling between surface plasmon polaritons (SPP) and excitons on fluorescence lifetimes and photobleaching effects. Our plasmonic‐photonic structure, comprising of thin silver (Ag) and gold (Au) layers with a Rhodamine 6G (R6G) dye layer, shows a clear shift in the plasmon resonance and R6G absorption lines with varying incident angles, indicative of strong coupling, with a measured Rabi splitting of approximately 90 meV. Fluorescence lifetime imaging microscopy (FLIM) was then employed to assess photobleaching, revealing a significant reduction in photobleaching effect for in strongly coupled plasmonic‐excitonic structures compared to single Rhodamine R6G layers. Our findings indicate the pivotal role of strong light–matter interactions in reducing photobleaching effects and stabilizing fluorescence intensities, offering promising avenues for developing quantum multiparticle nanophotonic devices with enhanced stability and performance.

A one-dimensional photonic crystal with an additional TiO₂ layer, supporting Bloch surface waves (BSW), was used for enhanced signal sensitivity for the detection of protein interaction. To compare the optical response of BSW and photonic crystals (PC), bovine serum albumin and specific antibodies against bovine serum were used as a model system. The results obtained show the enhanced sensitivity of p- and s-BSW components for the 1D PC sample with an additional TiO₂ layer. Furthermore, a higher sensitivity was obtained for the BSW component of p-polarization in the PC sample with an additional TiO₂ layer, where the sensitivity of the ellipsometric parameter Ψ was five times higher and that of the Δ parameter was eight times higher than those of the PC sample. The capabilities of BSW excitations are discussed from the sensitivity point of view and from the design of advanced biosensing.

In this study, we investigate the contribution of resonant and non‐resonant excitation conditions on the polariton decay dynamics of strongly coupled rhodamine 6G (R6G) and surface plasmon polariton (SPP). We showed proof of strong coupling between SPP and R6G exciton from the dispersion relations measured by total internal reflection ellipsometry (TIRE). From these it was determined that the coupling strength reaches g ≈ 200 meV. Further fluorescence methods were employed to demonstrate the emission from the lower polariton branch (LP). The fluorescence lifetime and back focal plane imaging techniques were implemented to study radiative polariton decay, for resonant and non‐resonant excitation conditions. Fluorescence decay measurements of plasmonic strong coupling regime showed considerably longer (ps) than expected lifetime values (fs). In our case the measured lifetimes cannot be explained without the influence of additional energy level in emission dynamics, such as incoherent transition from exciton reservoir to lower polaritonic branch. The fundamental understanding of coherent energy exchange dynamics has potential importance for development of quantum optical nanodevices, polaritonic lasers, polariton condensation.