To determine the gas temperature of an alternating current (ac) (50 kHz) arc discharge at atmospheric pressure in air, a Mach–Zehnder type interferometer was built, utilizing an He-Ne $(lambda=6328 hboxAA)$ laser source with vertical polarization and a power of 5 mW. Upon introducing the arc discharge into one of the interferometer arms, a displacement of interference fringes takes place with respect to its position without the discharge. Keeping in mind that displacement of the fringes is related to the difference of the optical path with the variation of the refraction index and with temperature change in the discharge zone; the latter was determined from the displacements of the interference fringes. At the center of the discharge channel, a temperature near 3000 K was calculated, diminishing gradually to room temperature toward the discharge borders. This temperature value at the center of the channel agrees with results previously reported in similar discharges. This is an alternate method for the diagnosis of plasma parameters used in the production and treatment of materials.

We design and evaluate the performance of a one-dimensional photonic crystal (PhC) optical filter that comprises the integration of alternating layers of a barium titanate ferroelectric $\left({\mathrm{BaTiO}}_3\right)$ and an yttrium oxide dielectric $\left({\mathrm{Y}}_2{\mathrm{O}}_3\right)$, with a critical high-temperature superconductor defect, yttrium–barium–copper oxide $\left({\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\mathrm{X}}\right)$, resulting in the ${(\mathrm{BTO}/{\mathrm{Y}}_2{\mathrm{O}}_3)}_{\mathrm{N}}/\mathrm{YBCO}/$${({\mathrm{Y}}_2{\mathrm{O}}_3/\mathrm{BTO})}_{\mathrm{N}}$ multilayered nanostructure array. Here, we demonstrate that such a nanosystem allows for routing and switching optical signals at well-defined wavelengths, either in the visible or the near-infrared spectral regions—the latter as required in optical telecommunication channels. By tailoring the superconductor layer thickness, the multilayer period number N, the temperature and the direction of incident light, we provide a computational test-bed for the implementation of a PhC-optical filter that works for both wavelength-division multiplexing in the 300–800 nm region and for high-Q filtering in the 1300–1800 nm range. In particular, we show that the filter’s quality factor of resonances Q increases with the number of multilayers—it shows an exponential scaling with N (e.g., in the telecom C-band, $Q\approx 470$ for $N=8$). In the telecom region, the light transmission slightly shifts towards longer wavelengths with increasing temperature; this occurs at an average rate of 0.25 nm/K in the range from 20 to 80 K, for $N=5$ at normal incidence. This rate can be enhanced, and the filter can thus be used for temperature sensing in the NIR range. Moreover, the filter works at cryogenic temperature environments (e.g., in outer space conditions) and can be integrated into either photonic and optoelectronic circuits or in devices for the transmission of information.

Recently, different biomedical applications of aluminum oxide (Al₂O₃) and zinc oxide (ZnO) have been studied, and they have displayed good biocompatible behavior. For this reason, this study explores nanolaminates of [Al₂O₃/ZnO]_n obtained by atomic layer deposition (ALD) on silicon (100) and 316L stainless steel substrates with different bilayer periods: n = 1, 2, 5, and 10. The intention is to correlate the structure, chemical bonds, morphology, and electrochemical properties of ZnO and Al₂O₃ single layers and [Al₂O₃/ZnO]_n nanolaminates with their cytotoxic and biocompatibility behavior, to establish their viability for biomedical applications in implants based on the 316L SS substrate. These nanolaminates have been characterized by grazing incident X-ray diffraction (XRD), finding diffraction planes for wurtzite type structure from zincite. The chemical bonding and composition for both single layers were identified through X-ray photoelectron spectroscopy (XPS). The morphology and roughness were tested with atomic force microscopy (AFM), which showed a reduction in roughness and grain size with a bilayer period increase. The thickness of the samples was measured with scanning electron microscopy, and the results confirmed the value of ~210 nm for the nanolaminate samples. The electrochemical impedance spectroscopy analysis with Hank’s balanced salt solution (HBSS) evidenced an evolution of [Al₂O₃/ZnO]_n/316L system corrosion resistance of around 95% in relation with the uncoated steel substrate as function of the increase in the bilayers number. To identify the biocompatibility behavior of these nanolaminate systems, the lactate dehydrogenase test was performed with Chinese hamster ovary (CHO) cells for a short system of life cell evaluation. This test shows the cytotoxicity of the multilayer compared to the single layers of Al₂O₃, ZnO, and 316L stainless steel. The lowest cytotoxicity was found in the single layers of ZnO, which leads to cell proliferation easier than Al₂O₃, obtaining better adhesion and anchoring to its surface.

Emergent technologies that make use of novel materials and quantum properties of light states are at the forefront in the race for the physical implementation, encoding and transmission of information. Photonic crystals (PCs) enter this paradigm with optical materials that allow the control of light propagation and can be used for optical communication, and photonics and electronics integration, making use of materials ranging from semiconductors, to metals, metamaterials, and topological insulators, to mention but a few. Here, we show how designer superconductor materials integrated into PCs fabrication allow for an extraordinary reduction of electromagnetic waves damping, making possible their optimal propagation and tuning through the structure, below critical superconductor temperature. We experimentally demonstrate, for the first time, a successful integration of ferroelectric and superconductor materials into a one-dimensional (1D) PC composed of $$({\text {B}}{\text {T}}{\text {O}}/{\text {Y}}{\text {B}}{\text {C}} {\text {O}})_{{\text {N}}}/{\text {S}}{\text {T}}{\text {O}}$$(BTO/YBCO)N/STO bilayers that work in the whole visible spectrum, and below (and above) critical superconductor temperature $$T_C=80\, {\hbox {K}}$$TC=80K . Theoretical calculations support, for different number of bilayers N, the effectiveness of the produced 1D PCs and may pave the way for novel optoelectronics integration and information processing in the visible spectrum, while preserving their electric and optical properties.