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

Abstract

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).

Design of an Integrated Optics Sensor Structure Based on Diamond Waveguide for Hemoglobin Property Detection

“…These two effects can be used in sensors structures for determining the optical properties of the cover layer (in this case, hemoglobin). Struk et al in [10,11,12] described the operation of integrated optics sensor structures for measuring changes in the refractive index or extinction coefficient of the cover layer, which requires the use of a grating coupler or circuit with prism coupler. One should note that the optical properties of the substrate also influence the modal field distribution in the sensors’ structures.…”

“…The prism coupler is responsible for coupling light from a laser into a planar waveguide. The light could be coupled into a waveguide if components of the wave vector along the way of propagation in the prism and in the waveguide layer have the same value, and correspond to one of the possible propagation components in the waveguide structure [7,10,12]:2sans-serifπλ0npsinΘ = βw = 2sans-serifπλ0Neff where: n p —refractive index of prism, Θ —angle of incidence of the light beam upon the base of the prism, β w —propagation constant in the waveguide layer, N eff —effective refractive index.…”

“…The grating coupler is responsible for uncoupling the light from waveguide to cladding. The mathematical condition of uncoupling light from waveguide by grating coupler is following [9,10]:βcsin(α) = βw+mo2sans-serifπΛ where: β c —propagation constant in the environment; β w —propagation constant in the waveguide structure, Λ—space period of the grating, m o —diffraction order.…”

“…The operating principle of an integrated optics structure for sensors and biosensors applications is mostly based on exploiting the evanescent field of a guided waveguide mode or based on exploiting the grating couplers [7,8,9,10,11,12,13,14,15]. The evanescent field of a guided waveguide mode penetrates the cover layer and the substrate layer [7,8,9,10,11,12,13,14,15]. Changes in the optical properties (e.g., refractive index or extinction coefficient) and geometric properties (e.g., thickness) of the cover layer affects on the effective refractive index or attenuation coefficient of light into waveguide structure.…”

Optical investigations of ZnO layers affected by some selected gases in the aspect of their application in optical gas sensors

“…The obtained layers were characterized by a low coefficient of attenuation of the optical signal -the coefficient of attenuating the optical modes propagating in the layers amounted to about α ∼ 3 dB/cm. Such layers have among others, been presented in [22,23]. ZnO films were deposited on a substrate, e.g.…”