Optoelectronic and Birefringence Properties of Weakly Mg Doped ZnO Thin Films Prepared by Spray Pyrolysis

MgxZn1−xO thin films were deposited on glass substrate with x varied between 0.01 and 0.05 by spray pyrolysis at a temperature of 450 °C. The structural investigation showed that all thin films had ZnO wurtzite structure with a preferred (002) orientation. The gap energy was calculated using Tauc’s plot and it decreased over the Mg content by 0.07 eV. The charge carriers’ density dropped by an order of 105 as Mg content increased whereas the resistivity and the mobility increased. SEM observations revealed a significant difference between undoped and doped thin films. A 632.8 nm laser source prism coupler revealed 2 optical modes for every thin film in each Transverse Electric and Transverse Magnetic mode, the birefringence of the Mg doped films was positive. Both ordinary and extraordinary refractive indexes were found to decrease as the Mg content increased. Great intention has been paid to the relation between the refractive, charge carriers density and the optical band gap.

Optoelectronic and Birefringence Properties of Weakly Mg Doped ZnO Thin films Prepared By Spray Pyrolysis.

MgxZn1−xO thin films were deposited on glass substrate with x varied between 0.01 and 0.05 by spray pyrolysis at a temperature of 450 °C. The structural investigation showed that all thin films had ZnO wurtzite structure with a preferred (002) orientation. The gap energy was calculated using Tauc’s plot and it decreased over the Mg content by 0.07 eV. The charge carriers’ density dropped by an order of 105 as Mg content increased whereas the resistivity and the mobility increased. SEM observations revealed a significant difference between undoped and doped thin films. A 632.8 nm laser source prism coupler revealed 2 optical modes for every thin film in each Transverse Electric and Transverse Magnetic mode, the birefringence of the Mg doped films was positive. Both ordinary and extraordinary refractive indexes were found to decrease as the Mg content increased. Great intention has been paid to the relation between the refractive, charge carriers density and the optical band gap.

An Overview of Artificial Olfaction Systems with a Focus on Surface Plasmon Resonance for the Analysis of Volatile Organic Compounds

The last three decades have witnessed an increasing demand for novel analytical tools for the analysis of gases including odorants and volatile organic compounds (VOCs) in various domains. Traditional techniques such as gas chromatography coupled with mass spectrometry, although very efficient, present several drawbacks. Such a context has incited the research and industrial communities to work on the development of alternative technologies such as artificial olfaction systems, including gas sensors, olfactory biosensors and electronic noses (eNs). A wide variety of these systems have been designed using chemiresistive, electrochemical, acoustic or optical transducers. Among optical transduction systems, surface plasmon resonance (SPR) has been extensively studied thanks to its attractive features (high sensitivity, label free, real-time measurements). In this paper, we present an overview of the advances in the development of artificial olfaction systems with a focus on their development based on propagating SPR with different coupling configurations, including prism coupler, wave guide, and grating.

Dual-Retarder Mueller Polarimetry System for Extraction of Optical Properties of Serum Albumin Protein Media

A dual liquid-crystal variable retarder Mueller polarimetry system incorporating a gold-based surface plasmon resonance prism coupler was proposed for extracting the optical properties of serum albumin protein media in the reflectance configuration. The feasibility of the proposed system was demonstrated by measuring the circular dichroism and circular birefringence properties of glucose tissue phantom solutions with different albumin concentrations. The results showed that the circular dichroism increased with albumin concentration, while the optical rotation angle increased with glucose concentration. Both properties reduced over time as a result of the protein glycation effect, which led to a gradual reduction in the glucose content of the sample.

Principles and Applications of Nanoplasmonics in Biological and Chemical Sensing: A Review

Biosensing requires a highly sensitive real-time detection of the biomolecules. These properties are granted by nanoplasmonic sensing techniques. SPR-based optical sensors have evolved as a sensitive and versatile biosensing tool. A growing number of SPR-based sensing applications in the solution of clinical problems are reported in the recent years. This refers to the point that these sensors provide label-free detection of the living cells and non-destructive analysis techniques. In this study, we will review the mechanism of the detection in SPR biosensing, followed by the methods used to develop sensors to detect gases and the chemical, biological, and molecular interaction. The device sensitivity improvement based on plasmonic effects is also addressed in this study, and accordingly, the size and material dependence of the resonance frequency are discussed. The reviewed articles are categorized into three groups, depending on the SPR excitation configuration. In the first group of the sensors, the sensitivity of LSPR-based sensors in prism coupler configurations is reviewed. The second group, SPR excitation by optical fiber, slightly improved the sensitivity of the detections. The unique capability of the third group, photonic crystal fiber SPR sensors, in providing greatly improved sensitivity, generated a vast field of researches and applications in biosensing devices.

Elaboration and Characterization of in Doped TiO2 Thin Films

Undoped and indium (In) doped TiO2 thin films were deposited by sol-gel method onto glass substrates. Structural, optical and electrical properties of films were studied. X-rays diffraction patterns showed that the TiO2 films consist of anatase phase. AFM images revealed that the surface roughness of In:TiO2 films is smoother than that of undoped TiO2 films. UV–Vis transmittance results showed TiO2 films have significant optical absorption in the region of 300–350 nm and are fully transparent in the visible. Both film thickness and refraction index in dependence on the fraction of In doping are derived from TE and TM optical guided modes excited in a prism coupler. The optical gap Eg decreases from 3.50 eV for undoped TiO2 film to 3.43 eV at 2 at.% In doping and then increases for doping with indium at 10 at.%. The electrical characterization shows a maximum electrical conductivity of 2.7 (S/cm) obtained for the film doped with 10 at.% In.