In this study, we present an experimental application of a label-free surface plasmon polaritons (SPP) method for the detection of CF®680 dye-labelled bovine serum albumin (BSA). We show the optical properties of the BSA-CF680 complex and the adsorption analysis of this bio-complex on the SPP sensing surface. The total internal reflection ellipsometry and fluorescence microscopy method were used to analyse the absorption and fluorescence properties of BSA-CF680. It was demonstrated that the SPP's quality factor increased when a labelled BSA-CF680 biomolecule complex was used compared to non-labelled BSA, indicating coupling between SPP and biomolecules. However, the number of biomolecules adsorbed to the surface shows that a higher emitter count or lower mode volume is required to reach the strong coupling regime. This approach of combining a label-free method with labelled biomolecules can pave the way for an alternative biomolecule detection method through spectral analysis.

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.

Back focal plane (BFP) imaging has emerged as a widely used technique for investigating various nanoscale optical devices. The ability to provide the full angular distribution of emitted light has enabled the engineering of precise radiation patterns, enabling new advances in nanophotonics. Continuous improvements in the BFP imaging technique, including wavelength, polarization, and phase-resolved signal detection, have allowed us to gain crucial insights into the various optical and material properties of nanophotonic devices. In this study, we introduce a fluorescence lifetime-resolved BFP imaging configuration, which uses a spatial filtering technique in the Fourier plane to discriminate between different emission directions. Uniform silver film (45 nm) with a PMMA matrix layer of about 20 nm containing Rhodamine 6G fluorescent molecular dye was prepared and measured using total internal reflection ellipsometry (TIRE). A coupled oscillator model was used, and strong coupling was observed with a coupling strength of 160 meV. Time-correlated single-photon counting was used for the estimation of fluorescence lifetime in the sub-nanosecond regime, and a direction-dependent lifetime was observed in the BFP imaging configuration. This modified fluorescence-lifetime-resolved BFP microscopy method is essential for directly correlating the collective quantum dynamics (lifetime/decay rate) with the far-field radiation pattern (angle/coherence). It offers a critical tool for designing and optimizing quantum nanophotonic devices, such as polariton-based components and highly directional single-photon emitters, where controlling both excited-state dynamics and spatial coherence is paramount.

Total internal reflection ellipsometry (TIRE) and leakage microscopy were applied for the study of photonic-plasmonic nanostructures supporting hybrid Tamm-surface plasmon modes and their strong coupling with Rhodamine 6G organic dye excitons. The optical response of TIRE has shown that Tamm and surface plasmon polaritons interact strongly and the formed hybrid plasmonic mode alters resonances in the energy spectra. Moreover, both TPP (Tamm plasmon polaritons) and SPP (surface plasmon polaritons) components in the hybrid mode are strongly coupled with R6G-PMMA (poly(methyl methacrylate)) layers at the inner and outer interfaces of the 50 nm gold layer, respectively. Leakage microscopy in the back focal plane optical configuration proves the energy transfer of excited emitters through the 50 nm gold layer in the strong coupling regime. Polaritonic emission in the strong coupling has better coherence properties than conventional spontaneous fluorescence emission from pure Rhodamine 6G organic dye molecules.

In this study, we demonstrate the potential capability to control Tamm plasmon-polaritons (TPP) by applying atomic layer deposition (ALD) as a highly precise technique for plasmonic applications. Applications in plasmonics usually require tens of nanometers or less thick layers; thus, ALD is a very suitable technique with monolayer-by-monolayer growth of angstrom resolution. Spectroscopic ellipsometry and polarized reflection intensity identified the TPP resonances in the photonic band gap (PBG) formed by periodically alternating silicon oxide and tantalum oxide layers. The sub-nanometer control of the Al2O3 layer by ALD allows precise tailoring of TPP resonances within a few nanometers of spectral shift. The employing of the ALD method for the fabrication of thin layers with sub-nanometer thickness accuracy in more complex structures proves to be a versatile platform for practical applications where tunable plasmonic resonances of high quality are required.

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.

The growth of the building integrated photovoltaic (BIPV) sector is limited by the apparent lack of ways to create the visual impact of the building at acceptable cost efficiency rates in the current PV market. Thus, in this research digital simulations were combined with experimental studies to design and optimize novel 1D photonic crystal structures acceptable to expand and improve the color palette of PV panels. It was proved that the 3-layered system with TiO2/SiO2/TiO2 was both efficient and sufficient for this purpose. Advanced light filtering was implemented experimentally on 5x5 size glass plates with a potentially cheap and simple sol-gel dipping technique with annealing only at 110 degrees C. The applicability of the proposed technology was validated by manufacturing the PV mini panels that showed 2-3 higher brightness in CIE color space compared to the panels made using commercial solar cells. Experimentally obtained efficiencies were: 18.75% (REF, black), 17.28% (light blue), 17.13% (greenish), 16.52% (yellowish), which is in the range to the commercial colored cells, but could be higher if better cells were used. The technology reliability and scalability were evaluated from analysis of the sensitivity of the 1D photonic crystal parameters to the optical properties of the colored device. The tolerable deviations from the color related numbers are approximately +/- 0.05 for the refractive index spectrum and less than approximately +/- 2% for the thickness. Therefore, the proposed coloring method should be a perspective solution for BIPV, but careful attention should be taken for the technological process optimization.

In this study, we present an analysis of the optical response of strong coupling between SPR and labeled proteins. We demonstrate a sensing methodology that allows to evaluate the protein mass adsorbed to the gold’s surface from the Rabi gap, which is a direct consequence of the strong light–matter interaction between surface plasmon polariton and dye exciton of labeled protein. The total internal reflection ellipsometry optical configuration was used for simulation of the optical response for adsorption of HSA-Alexa633 dye-labeled protein to a thin gold layer onto the glass prism. It was shown that Rabi oscillations had parabolic dependence on the number of labeled proteins attached to the sensor surface; however, for photonic–plasmonic systems in real experimental conditions, the range of the Rabi energy is rather narrow, thus it can be linearly approximated. This approach based on the strong coupling effect paves the alternative way for detection and monitoring of the interaction of the proteins on the transducer surface through the change of coupling strengths between plasmonic resonance and the protein–dye complex.

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 SHSPP ≈ 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%.

Biosensors are described as analytical devices in which biological substances are detected by using various physicochemical detection systems [...]

Controlling and increasing the propagation length between Tamm and surface plasmons under a strong coupling regime using surface lattice arrays leads to better coherence properties of hybrid plasmonic modes.

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.

Detailed evaluations of the antigen and antibody interaction rate and strength of the immune complex formed are very important for medical and bioanalytical applications. These data are crucial for the development of sensitive and fast immunosensors suitable for continuous measurements. Therefore, combined spectroscopic ellipsometry (SE) and quartz crystal microbalance with dissipation (QCM-D) technique (SE/QCM-D) was used for the evaluation: (i)of covalent immobilization of SARS-CoV-2 nucleocapsid protein (SCoV2-N) on QCM-D sensor disc modified by self-assembled monolayer based on 11-mercaptoundecanoic acid and (ii)interaction of immobilized SCoV2-N with specific polyclonal anti-SCoV2-N antibodies followed by immune complex formation process. The results show that the SCoV2-N monolayer is rigid due to the low energy dissipation registered during the QCM-D measurement. In contrast, the anti-SCoV2-N layer produced after interaction with the immobilized SCoV2-N formed a soft and viscous layer. It was determined, that the sparse distribution of SCoV2-N on the surface affected the spatial arrangement of the antibody during the formation of immune complexes. The hinge-mediated flexibility of the antibody Fab fragments allows them to reach the more distantly located SCoV2-N and establish a bivalent binding between proteins in the formed SCoV2-N/anti-SCoV2-N complex. It was noted that the SE/QCM-D method can provide more precise quantitative information about the flexibility and conformational changes of antibody during the formation of the immune complex on the surface over time.

The properties of the ZnO-NWs were investigated by utilizing spectroscopic ellipsometry under TIRE configuration during real-time measurement of covalent BSA immobilization.

During the pandemic, different methods for SARS-CoV-2 detection and COVID-19 diagnostics were developed, including antibody and antigen tests. For a better understanding of the interaction mechanism between SARS-CoV-2 virus proteins and specific antibodies, total internal reflection ellipsometry based evaluation of the interaction between SARS-CoV-2 nucleoprotein (SCoV2-rN) and anti-SCoV2-rN antibodies was performed. Results show that the appropriate mathematical model, which takes into account the formation of an intermediate complex, can be applied for the evaluation of SCoV2-rN/anti-SCoV2-rN complex formation kinetics. The calculated steric factor indicated that SCoV2-rN/anti-SCoV2-rN complex formation has very strict steric requirements. Estimated Gibbs free energy (Delta G(Assoc)) for SCoV-rN and antiSCoV-rN binding was determined as -34 kJ/mol. The reported findings are useful for the design of new analytical systems for the determination of anti-SCoV2-rN antibodies and for the development of new anti-SARS-CoV-2 medications. (C) 2021 Elsevier Inc. All rights reserved.

Low-cost 1D plasmonic photonic structures supporting Tamm plasmon polaritons and cavity modes were employed for optical signal enhancement, modifying the commercially available quartz crystal microbalance with dissipation (QCM-D) sensor chip in a combinatorial spectroscopic ellipsometry and quartz microbalance method. The Tamm plasmon optical state and cavity mode (CM) for the modified mQCM-D sample obtained sensitivity of ellipsometric parameters to RIU of ΨTPP = 126.78 RIU−1 and ΔTPP = 325 RIU−1, and ΨCM = 264 RIU−1 and ΔCM = 645 RIU−1, respectively. This study shows that Tamm plasmon and cavity modes exhibit about 23 and 49 times better performance of ellipsometric parameters, respectively, for refractive index sensing than standard spectroscopic ellipsometry on a QCM-D sensor chip. It should be noted that for the optical biosensing signal readout, the sensitivity of Tamm plasmon polaritons and cavity modes are comparable with and higher than the standard QCM-D sensor chip. The different origin of Tamm plasmon polaritons (TPP) and cavity mode (CM) provides further advances and can determine whether the surface (TPP) or bulk process (CM) is dominating. The dispersion relation feature of TPP, namely the direct excitation without an additional coupler, allows the possibility to enhance the optical signal on the sensing surface. To the best of our knowledge, this is the first study and application of the TPP and CM in the combinatorial SE-QCM-D method for the enhanced readout of ellipsometric parameters.

Surface plasmon polaritons (SPPs) based light–matter interactions play a major role in photonic sensor applications. In order to implement such sensors in microchip devices or reduce the fabrication costs, a method with high flexibility and large‐scale capabilities must be developed. Here, the formation of large‐scale gold microbumps arrays by using a direct laser writing technique is presented. The fabricated arrays exhibit the hybrid lattice plasmon polaritons in the Vis–NIR range, in the same range as metallic gratings fabricated by lithography‐based techniques. The peak of hybrid lattice plasmon resonance depends on the period of the fabricated arrays, the thickness of the gold film, coupled light polarization, and sample orientation. The experimental results are in good agreement with the theoretical estimation. The demonstrated method shows relevant technological progress in the formation of large‐scale metallic gratings by using a cost‐effective laser‐based technique. It provides new opportunities for hybrid lattice plasmon polariton (HLPP)‐based applications in biotechnology, photonics, plasmonics, and so on.

Total internal reflection ellipsometry was employed for the excitation and study of hybrid Tamm plasmon-surface plasmon polaritons mode. Simple optical methodology using optical filters to cut the part of incident light spectra was proposed. Using optical filters measured energy spectra was divided into two parts where in each range only one branch of the hybrid TPP-SPP plasmonic mode was excited directly by the incident light. Present experimental studies have shown, that if the investigated system is in strong coupling, this is always enough to excite only one component of the hybrid excitation. Thus, its dispersion relation will be the same as when the excitation is done with a whole spectrum. In the case of the TPP-SPP hybrid mode where strong coupling is realized only in p-polarized light, the fitting results have shown that the strongest coupling was at the point where the noninteracting TPP and SPP curves should be crossing. The obtained Rabi splitting for the hybrid TPP and SPP modes in BK7 prism/1D PC TiO 2 /SiO 2 (60 nm/110 nm)/TiO 2 (30 nm)/Au (40 nm) multilayered structure was about 105 meV.

The total internal reflection ellipsometry method was used to analyse the angular spectra of the hybrid Tamm and surface plasmon modes and to compare their results with those obtained using the conventional single SPR method. As such type of measurement is quite common in commercial SPR devices, more detailed attention was paid to the analysis of the p-polarization reflection intensity dependence. The conducted study showed that the presence of strong coupling in the hybrid plasmonic modes increases the sensitivity of the plasmonic-based sensors due to the reduced losses in the metal layer. The experimental results and analysis of the optical responses of three different plasmonic-based samples indicated that the optimized Tamm plasmons ΔRp(TP) and optimized surface plasmons ΔRp(SP) samples produce a response that is about five and six times greater than the conventional surface plasmon resonance ΔRp(SPR) in angular spectra. The sensitivity of the refractive index unit of the spectroscopic measurements for the optimized Tamm plasmon samples was 1.5 times higher than for conventional SPR, while for wavelength scanning, the SPR overcame the optimized TP by 1.5 times.