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In this paper, we studied the transmission properties, including photonic band gap (PBG) and defect mode properties, of one-dimensional photonic crystals (1D PCs) consisting of gradient materials. When keeping the average refractive index of the gradient materials in the 1D gradient-material PCs (1D GPCs) the same as the index of the corresponding normal materials in the 1D normal-material PCs (1D NPCs), by transfer matrix method, we found that the complete 1D GPCs with high-index gradient materials benefit to achieve larger omni-PBG than that in 1D NPCs. In our high-index gradient material case, for TE(TM) wave, the optimal omni-PBGs in 1D GPCs with first- and second-order gradient materials are 38.6% (50.2%) and 15.9% (22.3%) larger than that in 1D NPCs; while for the optimal relative bandwidths of omni-PBG, the corresponding promotions are 41.1% (52.3%) and 16.1% (22.6%), respectively. In addition, when defective 1D GPCs have gradient-material defect, the position of defect modes can be adjusted by selecting proper parameters of the gradient materials. These types of research are useful for designing wide PBG devices and tunable narrow-band filters which have potential application in optical communication.

In the present communication, we report on the exploitation of a Bloch surface wave-enhanced fluorescence scheme for the detection of Interleukin (IL)-10 in a protein-rich buffer mimicking a biological sample. IL-10 is a cytokine known for its potent anti-inflammatory and immunosuppressive effects. It is considered a valuable biomarker for prognostic prediction for both solid tumors and hematological malignancies, and recently, a distinguishing feature of hyperinflammation during severe viral infections. To demonstrate the validity of the technique, we transferred all the reagents and working concentrations used in a gold-standard technique, such as ELISA, to our assay, with a substantial reduction in the execution time and without using any enzymatic amplification during IL-10 recognition. We estimate a limit of detection (LoD) in terms of the concentration of IL-10 in solution of the order of 110 pg/mL (5.8 pM) with a 14% accuracy; in other terms, the presented technique is compatible with the assay range and resolution (1.6 pM) of commercial gold-standard ELISA kits. Moreover, such LoD successfully matches the concentrations reported in literature for IL-10 detection in COVID-19 patients, making the BSW-based sensors a viable solution for rapid and accurate screening of COVID-19-related molecules.

In the current study, we aim to limit the power dissipation in amorphous silicon solar cells by enhancing the cell absorbance at different incident angles. The current improvement is justified by adding the single-period of ternary 1D photonic crystal with texturing on the top surface, which acts as an anti-reflecting coating. The texturing shape gives the photons at least two chances to localize inside the active area of the cell. Therefore, it increases the absorbance of the cell. Moreover, we add binary one-dimensional photonic crystals with the features of a photonic band gap, which acts as a back mirror to return the photons that were transmitted inside the cell’s active region. The considered structure is demonstrated by the well-defined finite element method (FEM) by using COMSOL multiphysics.

In this paper, by using the transfer matrix method and introducing the plasma as the dispersion medium, we propose the tunable one-dimensional magnetized ternary plasma photonic crystal structure ( APB ) N , and study its omnidirectional absorption properties of TM wave in terahertz band, where A and B are two different dielectric layers, P is plasma layer, and studied the regulation of the frequency and peak of the absorption channel by the number of periods, the relative refractive index of the dielectric layer, length, density, collision frequency and magnetic field intensity of the plasma layer to the absorption channel frequency and peak value. Therefore, this paper provides an idea for the design of terahertz absorbers for omnidirectional plasma photonic crystals.

In this paper, we present a high-efficiency narrow band filter (NBF) based on quasi-one-dimensional photonic crystal (PC) with a mirror symmetric heterostructure. Similarly to the Fabry-Perot-like resonance cavity, the alternately-arranged dielectric layers on both sides act as the high reflectance and the junction layers used as the defect mode of the quasi-one-dimensional PC, which can be designed as a NBF. The critical conditions for the narrow pass band with high transmittance are demonstrated and analyzed by simulation and experiment. The simulation results indicate that the transmission peak of the quasi-one-dimensional PC-based NBF is up to 95.99% at the telecommunication wavelength of 1550 nm, which agrees well with the experiment. Furthermore, the influences of the periodicity and thickness of dielectric layers on the transmission properties of the PC-based NBF also have been studied numerically. Due to its favorable properties of PC-based NBF, it is can be found to have many potential applications, such as detection, sensing, and communication.

Optical biosensors based on one-dimensional photonic crystals sustaining Bloch surface waves are proposed to study antibody interactions and perform affinity studies. The presented approach utilizes two types of different antibodies anchored at the sensitive area of a photonic crystal-based biosensor. Such a strategy allows for creating two or more on-chip regions with different biochemical features as well as studying the binding kinetics of biomolecules in real time. In particular, the proposed detection system shows an estimated limit of detection for the target antibody (anti-human IgG) smaller than 0.19 nM (28 ng/mL), corresponding to a minimum surface mass coverage of 10.3 ng/cm2. Moreover, from the binding curves we successfully derived the equilibrium association and dissociation constants (KA = 7.5 &times, 107 M&minus, 1, KD = 13.26 nM) of the human IgG&ndash, anti-human IgG interaction.

We report on hybrid inorganic/organic one-dimensional photonic crystal biochips sustaining Bloch surface waves. The biochips were used, together with an optical platform operating in a label-free and fluorescence configuration simultaneously, to detect the cancer biomarker Angiopoietin 2 in a protein base buffer. The hybrid photonic crystals embed in their geometry a thin functionalization poly-acrylic acid layer deposited by plasma polymerization, which is used to immobilize a monoclonal antibody for highly specific biological recognition. The fluorescence operation mode is described in detail, putting into evidence the role of field enhancement and localization at the photonic crystal surface in the shaping and intensification of the angular fluorescence pattern. In the fluorescence operation mode, the hybrid biochips can attain the limit of detection 6 ng/ml.

We report on the use of an optical sensing platform based on Bloch surface waves sustained by one-dimensional photonic crystals as a novel optical tool to probe in real time the fluid flow at a boundary wall of a microfluidic channel under dynamic conditions. Understanding how fluid flow interacts with wall surfaces is crucial for a broad range of biological processes and engineering applications, such as surface wave biosensing. The proposed platform provides nanometric resolution with respect to the distance from the boundary wall sensor's surface. Here, for the first time, we report on the experimental investigation on the temporal evolution of the interface between two fluids with different refractive indices under convective and diffusive conditions. The temporal evolution of the fluids interface in proximity of the wall is recovered. From the data analysis, the diffusion coefficients of glucose and glycerol in water are measured and found in good agreement with the literature. Tuning the one-dimensional photonic crystals geometry and the Bloch surface wave's dispersion has the potential to probe the fluid flow in an extremely wide range of distances from the microfluidic channel wall.

Accessed by 09/2014; International audience; The preparation of responsive multilayered structures with quarter-wave designbased on layer-by-layer deposition of sol-gel derived Nb2O5 films and spin-coated MELtype zeolite is demonstrated. The refractive indices (n) and thicknesses (d) of the layers aredetermined using non-linear curve fitting of the measured reflectance spectra. Besides, thesurface and cross-sectional features of the multilayered structures are characterized byscanning electron microscopy (SEM). The quasi-omnidirectional photonic band for themultilayered structures is predicted theoretically, and confirmed experimentally byreflectance measurements at oblique incidence with polarized light. The sensing propertiesof the multilayered structures toward acetone are studied by measuring transmittancespectra prior and after vapor exposure. Furthermore, the potential of the one-dimensionalphotonic crystals based on the multilayered structure consisting of Nb2O5 and MEL typezeolite as a chemical sensor with optical read-out is discussed.