Agriculture challenges to reduce its environmental impact and to improve control over agricultural crops of agriculture are numerous. We develop here an optical integrated probe as potential answer to some detection challenges, based on a RIB chalcogenide waveguide. Early results have shown that the fabrication process induces sidewall roughness potentially altering the sensitivity of the probe. The numerical tool used here implements an approximation allowing to take into account sidewall roughness on propagation losses. This code is based on finite element method. Results show that sidewall roughness have a higher impact on losses for thin waveguides. Additionally, etching tests have been carried out to investigate the impact of oxygen concentration in the etching chamber over the quality of the sidewall. Results show that the more oxygen, the more important the roughness of the sidewall.

We offer here an accurate quantitative model of the RIA (radiation-induced absorption) at low dose-rate (below 1 kGy) that experience the most common erbium-doped fibers (Ge-Al-Er-doped silica) under radiations. It addresses the degradation mechanisms of the glass fiber, especially the influence of its doping elements versus its sensitivity to radiations. Moreover, it depends mainly on macroscopic quantities coming from literature or experiments. For these two reasons, it is a reliable and efficient tool for the engineering of erbium-doped fibers (erbium-free fibers too) exposed to ionizing radiations and is validated in this paper by comparing the modelisation results to RIA experiments on 14 Er-doped optical fiber samples, in which composition changes a lot from one sample to another (in the range 0-25%wt for Ge, 0-10%wt for Al and 0-1500ppm for Er).

The leaf coverage surface is a key measurement of the spraying process to maximize spray efficiency. To determine leaf coverage surface, the development of optical micro-sensors that, coupled with a multivariate spectral analysis, will be able to measure the volume of the droplets deposited on their surface is proposed. Rib optical waveguides based on Ge-Se-Te chalcogenide films were manufactured and their light transmission was studied as a response to the deposition of demineralized water droplets on their surface. The measurements were performed using a dedicated spectrophotometric bench to record the transmission spectra at the output of the waveguides, before (reference) and after drop deposition, in the wavelength range between 1200 and 2000 nm. The presence of a hollow at 1450 nm in the relative transmission spectra has been recorded. This corresponds to the first overtone of the O–H stretching vibration in water. This result tends to show that the optical intensity decrease observed after droplet deposition is partly due to absorption by water of the light energy carried by the guided mode evanescent field. The probe based on Ge-Se-Te rib optical waveguides is thus sensitive throughout the whole range of volumes studied, i.e., from 0.1 to 2.5 μL. Principal Component Analysis and Partial Least Square as multivariate techniques then allowed the analysis of the statistics of the measurements and the predictive character of the transmission spectra. It confirmed the sensitivity of the measurement system to the water absorption, and the predictive model allowed the prediction of droplet volumes on an independent set of measurements, with a correlation of 66.5% and a precision of 0.39 μL.

Nowadays, plant protection still calls on pesticides to prevent disease and pests. This use of phytosanitary inputs became a main issue in the agriculture field, due to the off-target spray particles movement that fails to reach their target when pesticides are applied to crops, these spray drops contaminate the outer regions of the treated area. This spraying loss has a negative impact on environmental, health and economic problems. One of the way to improve the spraying quality is to estimate the off-target volumes, this information could thus help farmers to optimize their planting performances. Several methods to quantify spray deposition in field conditions have been developed [1–4] such as the use Water Sensitive Paper (WSP) cards. However, these methods are time consuming and has a lack of accuracy. ∗Speaker †Corresponding author: anis.taleb-bendiab@irstea.fr ‡Corresponding author: maxime.ryckewaert@limagrain.com §Corresponding author: caroline.vigreux@univ-montp2.fr ¶Corresponding author: kribich@ies.univ-montp2.fr ‖Corresponding author: Raphael.Escalier@univ-montp2.fr ∗∗Corresponding author: ryad.bendoula@irstea.fr sciencesconf.org:nanosen-aqm:260394 The objective of this work is to create an optical sensor based on a RIB waveguide design to characterize the quantity and distribution of a liquid spray deposit. The conception idea is that we assumed that the light guidance properties of these sensors would undergo a modification when spraying droplets are present on their surface. This phenomenon results from partial evanescent wave absorption by the water, highly present in pesticides, which leads to a decrease in the transmitted intensity at the waveguide output. We firstly studied on an optical bench the influence of a droplet deposits on the waveguide using different droplet volumes (0 to 10 μl). The result obtained was a gradual decrease in the output intensity signal due to the water absorbtion of the evanescent field, and this proportionally to the droplet volume; the bigger the droplet, the greater the loss in output intensity. [5] Secondly, we performed a second test by successively adding 2.5 μl droplets alongside the waveguide to analyze their cumulative influence. We found out that the decrease in output intensity is also proportionally related to the number of droplets present on the waveguide. [5]In addition, we performed an other test on a spectral analysis bench in order to highlight the light absorption at the specific water wavelenght using the output spectrum. this test aimed to confirm the link between the volume and the absorption to certify the first approach. We proceeded to a droplet deposition on the waveguide with a volume range from 0,1 to 2.5 μl droplets to analyze the sepctra at the output. The result showed that we can see an absorption at 1450μm wavelenght wich is one of the water wavelenght absoprtion. This investigation also exposed the link between the droplet volume and the absorption rate. To conclude, these first results demonstrate the potential of RIB waveguide sensors to accurately quantify droplet deposits and can potentially be used to analyze a chemical composition of a liquid present on the waveguide surface. Our future work should focus on improving the waveguide architecture in order to estimate deposited volumes and also the number of deposited droplets.

With the aim to develop optical micro-sensors for "on-line" measurement of spray deposits on plant leaves, and thus to optimize the use of phytosanitary inputs in agriculture, straight waveguides based on GeSeTe chalcogenide layers were elaborated and their sensitivity to water droplet deposition was tested. As expected, water, the main constituent of pesticides, absorbed part of the evanescent wave of the guided light, which led to a decrease in the intensity transmitted at the output of the waveguides. Both experimental and simulation results proved that the position of the drop on the waveguide had no impact on the intensity measured at the guide outlet. At the opposite, they highlighted the correlation between the light intensity at the outlet and the volume and number of deposited droplets: the greater the volume of the drop and the greater the number of drops, the greater the decrease in intensity.

The reduction of inputs is a strategic stake for the wine industry, the main consumer of plant protection products. The development of research / experimentation and technical transfer on this topic over the past few years reflect this ambition shared by all actors. If efforts are mainly based on finding alternative products or developing decision support tools (DAOs) to reduce doses of applied products, optimizing the quality of spraying is also an important lever and can be directly mobilized by the winegrowers. The “spray deposit” is an indicator that reveals the dose received locally by the various organs of the plant that the treatment aims to protect. Thus, the “spray deposition” measure provides valuable information for optimizing the use of inputs. At present, the measurement of this surface quantity (surface covered, size of drops) is based on a constraining and tedious implementation based on artificial collectors. This operation requires to install and then retrieve all the collectors (more than a hundred in general) completely manually. Then, the analyzes are done in laboratory, which mobilizes time, manpower and consumables. Thus, automation of this measure would make it possible to acquire more references mobilizable by the manufacturers of sprayers to optimize their machines and the farmers themselves with a view to defining more precisely the optimal dose to be used thus causing a reduction in the use of plant protection products. In this context, our objective would be to develop optical sensors to characterize the quantity and distribution of a liquid spray. These optical sensors will have waveguides as basic bricks: the idea will be to analyze the impact of a liquid spray on the surface of the guides on their light guiding properties.

We report the design of a new type of scanning near-field optical microscopy probes combining the advantages of both tapered optical fibres type and cantilever type commercial scanning near-field optical microscopy probes. The material is an organomineral synthesized by the sol-gel method. This material matches mechanical and optical performances for such a scanning near-field optical microscopy probe fabrication. Numerical calculations were carried out using finite element method in order to study the optical transmission of the probe in emission and collection modes. The influence of the probe geometry on the intensity distribution in the vicinity of the aperture and in the extremity of the cantilever is studied in details.

In a context where the control of gases becomes important in a wide range of applications - health care, industry, housing, transportation, environment - we have in sight the realization of infrared optical micro-sensors. In particular, we wish to develop an optical micro-sensor operating at the wavelength 4.23 μm, wavelength corresponding to an absorption band of carbon dioxide, the main greenhouse gas.

In a context where the control of gases becomes important in a wide range of applications - health care, industry, housing, transportation, environment - we have in sight the realization of infrared optical micro-sensors. In particular, we wish to develop an optical micro-sensor operating at the wavelength 4.23 mu m, wavelength corresponding to an absorption band of carbon dioxide, the main greenhouse gas.The first step consists in manufacturing straight waveguides that were capable of operating at this wavelength. They are obtained by stacking and etching layers of the ternary system Ge-Se-Te. The waveguides opto-geometrical parameters such as refractive indices, thicknesses of the layers, etching depth and waveguide core width are set through a design process to obtain a single mode behaviour at 4.23 mu m. After fabrication, straight waveguides are optically characterized at lambda = 4.23 mu m on a bench dedicated to the study. The second step consists in designing circuits such as Y-junctions or Mach-Zehnder interferometers, still being able to operate at lambda = 4.23 mu m, whereas the last step consists in studying the possibility of integrating a CO2-sensitive layer to the circuits, in order to fabricate a micro-sensor.As this stage, straight waveguides were fabricated and proved to transmit light at lambda = 4.23 mu m, with propagation losses at about 1.3 dBcm(-1). Y-junctions and Mach-Zehnder interferometers are under fabrication, and possible sensitive layers are under investigation.

This article addresses the main results of the PEPS (PEllet Photonic Sensor) project, whcich aims at developing a new gas sensing transducer via a technological breakthrough: the combination of photonics (insensitive to external electromagnetic disturbances) and catalysis (reversibility, limited energy consumption). Indeed, catalytic reactions are often exothermic and this heat can modify the properties of optical devices. The experimental studies performed during the PEPS project highlighted the rapid and reversible response at room temperature of catalytic powders towards different concentrations of H2 in air. The thermal and optical properties of the materials used for the integrated photonic component have also been studied. These results have been exploited for the design of the photonic transducers. The feasibility of the physical transduction principle has been demonstrated by developing different prototypes based on Bragg gratings and Multimode Interference Components.

In a context where the control of gases becomes important in a wide range of applications - health care, industry, housing, transportation, environment, etc. - we have in sight the realization of infrared optical micro-sensors. In particular, we wish to develop an optical micro-sensor operating at the wavelength 4.26 µm, wavelength corresponding to an absorption band of carbon dioxide, the main greenhouse gas. The first step consists in manufacturing straight waveguides, but also circuits such as Y-junctions or interferometers, that are capable of operating at this wavelength. The straight waveguides and other guiding structures are obtained by stacking and etching of layers of the ternary system Ge-Se-Te, a chalcogenide system widely studied for its transparency properties in the infrared. Manufacturing objects are realized by: (i) depositing a first low refractive index Ge-Se-Te layer (buffer layer) on a Si substrate by thermal co-evaporation; (ii) depositing a second layer Ge-Se-Te characterized by a higher refractive index (guiding layer), again by thermal co-evaporation, and (iii) modifying the geometry of the second layer by laser lithography and ion beam etching. The waveguides opto-geometrical parameters such as refractive indices, thicknesses of the layers, etching depth and waveguide core width are set through a design process to obtain a single mode behavior at 4.26 µm. After fabrication, objects are optically characterized at λ = 4.26 µm on a bench dedicated to the study.

We present the design, batch fabrication sequences and mechanical characterization of an optical nearfield probe. The probe structure is made of a hybrid organo-mineral material synthesized using a sol-gel process. The cantilever-type probe was designed for Scanning Near-field Optical Microscopy (SNOM) in collection mode and its design was optimized by simulations. The mechanical properties of the probes were measured and topographical images of a standard surface obtained with the fabricated probes are presented. (c) 2014 Elsevier B.V. All rights reserved.

Development of micro-components for IR integrated optic devices requires the elaboration of IR waveguides. It is shown that amorphous chalcogenide films from the Ge-Se-Te system are well suited to such development. Thermal and optical characteristics of films elaborated by thermal co-evaporation are first measured. The Se-rich (> 60 at. %) region with a Ge content of about 25 at. % comprises films with a vitreous transition temperature, T-g, larger than 400K, a high thermal stability (Delta T > 100K) and a well-controlled refractive index, n, owing to a weak dependence of n with composition in this region. Films in this composition region are then profitably used to develop optical structures, such as straight or S-bend waveguides, spirals, Y-junction or Mach-Zehnder interferometer, by stacking and further etching of the films. The transmission region accessible to these structures lies from telecommunication wavelength up to 16-17 mu m. When a higher transmission region is required, the use of pure Ge-Te films is mandatory. A modal filter allowing a light rejection efficiency of 6.10(-5) to be a part of a spatial interferometer is then elaborated. (C) 2014 Optical Society of America

Films in a wide range of compositions in the Te-Ge-Se ternary system were prepared by thermal co-evaporation. The evolution of optical and thermal properties versus the composition has been used to determine an area of particularly interesting compositions for manufacturing waveguides being able to operate from 1 to about 17 μm. Rib waveguides based on these compositions were fabricated by using laser lithography and ion beam etching. Their optical losses were estimated to be 1.2 ± 0.6 dB·cm-1 at λ = 1.55 μm.

In this paper, we will demonstrate a theoretical approach to determining the optical response of interferometric detector systems to external stimuli. The wavelength dispersion of the refractive index and the thermo-optic coefficient of transparent polymer blend waveguide materials are inserted into modeling software in order to simulate the optical response of both Multimode Interferometer (MMI) and Bragg grating (BC) architectures. The optical output of such devices is very sensitive to variations in the refractive index of the constituent materials, and they may be used to detect phenomena such as local temperature changes or relative humidity variations [1]. When the input intensity of the sensor system is normalized to unity, we demonstrate theoretical thermal sensitivities of 2 x 10(-4)/K for BC architectures and 3 x 10(-5)/K for MMI devices. A differential measurement system for BC or MMI components is discussed and simulated. We shall also discuss the use of such systems as gas detectors when a catalyst capable of accelerating the exothermic oxidation of combustible gasses is deposited onto the optical circuit. (C) 2013 Elsevier B.V. All rights reserved.