P. Struk

Photonic structures with grating couplers based on ZnO

The paper presents investigations concerning the design and realization of photonic structures with grating couplers. The first part of the paper deals with basic theoretical information on photonic structures with grating couplers and their application in optoelectronics. The further part presents the results of numerical investigations on photonic structures with grating couplers and shows the influence of geometrical parameters on the effectiveness of the input and output of optic power into and out of this photonic structure. The paper also provides the results of experimental investigations on a wideband gap semiconductor, viz. zinc oxide ZnO, as well as its application in planar waveguide structures and photonic structures with grating couplers.

Numerical analyses of optical couplers for planar waveguides

The paper presents the results of numerical analyses of optical structures realized in the form of planar waveguides made of materials with high values of the refractive index n ≈1.85. The analysed structures consist of a waveguide and input-output systems. Input-output couplers are realized in the form of prisms as well as Bragg’s grating couplers. Numerical investigations were carried out by applying the finite difference time domain (FDTD) method.

Hybrid photonics structures with grating and prism couplers based on ZnO waveguides

This paper presents the results of investigations concerning input-output systems of an electromagnetic wave in the visible and near visible spectrum for their application in structures of integrated optics. The input-output structures used in described planar optical waveguides are in a form of prism and grating couplers. The first part of the paper contains numerical analysis of grating couplers aiming at an optimization of their geometrical parameters, strictly — the depth of the grooves in the grating coupler. The second part presents the practical realization, as well as experimental tests of the planar optical waveguide with the hybrid input-output system. As the input system of the electromagnetic wave, a prism coupler was used, and in the case of the output system — a photonic structure with grating coupler was applied. The investigated planar wave guides with the input-output structures were made of a wide energy band gap semiconductor — zinc oxide (ZnO).

Nanolayers in Fiber-Optic Biosensing

Abstract In this chapter, fiber-optic sensors based on nanolayers or thin films and their ability to perform biophotonic measurements is presented. In the last decade, fiber-optic sensors have gained popularity as biosensing devices. This has been made possible because of the design and the integration of new materials in fiber-optic technology. Nanolayers and thin films made from various materials such as nanodiamond (NCD), boron-doped nanodiamond (B-NCD), zinc oxide (ZnO), titanium dioxide (TiO2), and aluminum oxide (Al2O3) have been successfully applied in the construction of fiber-optic sensors. NCD and B-NCD have been synthesized by the chemical vapor deposition (CVD) methods, while oxide- and nitride-based thin films were designed using atomic layer deposition. These nanolayers and thin films have been widely used in fiber-optic sensor technology as a protective coating, reflective layers, and/or as a sensing medium.

Nitrogen-Doped Diamond Film for Optical Investigation of Hemoglobin Concentration

In this work we present the fabrication and characterization of a diamond film which can be utilized in the construction of optical sensors for the investigation of biological samples. We produced a nitrogen-doped diamond (NDD) film using a microwave plasma enhanced chemical vapor deposition (MWPECVD) system. The NDD film was investigated with the use of scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy. The NDD film was used in the construction of the fiber optic sensor. This sensor is based on the Fabry–Pérot interferometer working in a reflective mode and the NDD film is utilized as a reflective layer of this interferometer. Application of the NDD film allowed us to obtain the sensor of hemoglobin concentration with linear work characteristics with a correlation coefficient (R2) equal to 0.988.

Diamond-based protective layer for optical biosensors

Optical biosensors have become a powerful alternative to the conventional ways of measurement owing to their great properties, such as high sensitivity, high dynamic range, cost effectiveness and small size. Choice of an optical biosensors materials is an important factor and impacts the quality of the obtained spectra. Examined biological objects are placed on a cover layer which may react with samples in a chemical, biological and mechanical way, therefore having a negative impact on the measurement reliability. Diamond, a metastable allotrope of carbon with sp3 hybridization, shows outstanding properties such as: great chemical stability, bio-compatibility, high thermal conductivity, wide bandgap and optical transparency. Additionally it possesses great mechanical durability, which makes it a long-lasting material. The protective diamond thin films were deposited on the substrate using Microwave Plasma Assisted Chemical Vapor Deposition (MW PA CVD) system. The surface morphology and roughness was assessed with atomic force microscopy and profilometry. We have performed a series of measurements to assess the biocompatibility of diamond thin films with whole blood. The results show that thin diamond protective layer does not affect the red blood cells, while retaining the sensors high resolution and dynamic range of measurement. Therefore, we conclude that diamond thin films are a viable protective coating for optical biosensors, which allows to examine many biological elements. We project that it can be particularly useful not only for biological objects but also under extreme conditions like radioactive or chemically aggressive environments and high temperatures.

Investigation of physical properties of ZnO semiconductor material for biocompatible coating layer applications

The paper presents investigation of physical properties of ZnO semiconductor for biomedical applications as a coating layer for example in medical devices and structures. The research was focused on determination of surface topography by SEM method, surface roughness by AFM method, chemical composition by EDS method and crystalline structure of ZnO by Raman spectroscopy. The investigated ZnO coating was deposited by reactive magnetron sputtering on quartz substrate.

Low-coherence sensors with nanolayers for biomedical sensing

In this paper, we describe the fiber optic low-coherence sensors using thin film. We investigated their metrological parameters. Presented sensors were made with the use of standard telecommunication single mode optical fiber (SMF- 28). Different materials were applied to obtain thick layers, such as boron doped diamond, silver and gold. The thickness of layers used in the experiments ranged from 100 nm to 300 nm. Measurements were performed with broadband source operating at central wavelength 1300 nm. The measurement signal was acquired by an optical spectrum analyzer. Measured signal was analyzed in the spectrum domain. Any change of the phase difference between interfering beams reflected from the sensor head depends on measurand occurred in the spectrum of the measurement signal. We obtain the visibility value of the measured signal equal to 0.97.

ZnO semiconductor for applications in optoelectronics sensors structures

The paper presents numerical analysis of integrated optics structure in the form of planar waveguide based on polymer material (SU-8) with additional cover layer based on wide band gap oxide semiconductor – zinc oxide (ZnO). The theoretical studies of integrated optics structure presented in the paper was focused on determination of waveguide properties such as: modal field distribution and effective refractive index Neff as a function of optical and geometrical properties of waveguide and cover layer. The theoretical studies presented in the paper was carried out for two type of planar waveguide structure: without additional cover layer and with additional cover layer based on ZnO. The second part of the paper presents experimental results focused on technology of a single mode planar waveguide based on SU-8 polymer.

Physical and optical properties of TiO2 nanolayers for integrated photonics application

The paper presents investigation of physical properties of wide bandgap oxide semiconductor – titanium dioxide for applications in integrated photonics as well as for future applications in gas sensors structures. The investigation presented in the paper was focused on: surface topography of TiO2 layer measured by AFM method, as well as investigation of Raman shift obtained by Raman spectroscopy. Finally the integrated photonics in the form of planar waveguide is also presented.