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A cost-effective optical sensor for continuous in-situ monitoring of turbidity and suspended particulate matter concentration (SPM), with a production cost in raw materials less than 20 €, is presented for marine or fluvial applications. The sensor uses an infrared LED and three photodetectors with three different positions related to the light source-135º, 90º and 0º-resulting in three different types of light detection: backscattering, nephelometry and transmitted light, respectively. This design allows monitoring in any type of environment, offering a wide dynamic range and accuracy for low and high turbidity or SPM values. An ultraviolet emitter-receiver pair is also used to differentiate organic and inorganic matter through the differences in absorption at different wavelengths. The optical transducers are built in a watertight structure with a radial configuration where a printed circuit board with the electronic signal coupling is assembled. An in-lab calibration of the sensor was made to establish a relation between suspended particulate matter (SPM) or the turbidity (NTU) to the photodetectors' electrical output value in Volts. Two different sizes of seashore sand were used (180 µm and 350 µm) to evaluate the particle size susceptibility. The sensor was tested in a fluvial environment to evaluate SPM change during sediment transport caused by rain, and a real test of 22 days continuous in-situ monitoring was realized to evaluate its performance in a tidal area. The monitoring results were analysed, showing the SPM change during tidal cycles as well as the influence of the external light and biofouling problems. ; Funding Agency Programa Operacional Regional do Norte (NORTE2020), through Fundo Europeu de Desenvolvimento Regional (FEDER) NORTE-01-0145-FEDER-000032 European Union through the European Regional Development Fund, based on COMPETE 2020 (Programa Operacional da Competitividade e Internacionalizacao), project ICT UID/GEO/04683/2013 POCI-01-0145-FEDER-007690 Fundacao para a Ciencia e a Tecnologia ...

AbstractThis treatise showcases the design as well as modeling about a photodetector (PD) based on AgInSe2 (AISe), a direct bandgap chalcopyrite with a bandgap of 1.19 eV. The PD exhibits outstanding optical and electronic characteristics, showcasing remarkable performance. The PD has been systematically investigated by varying the width, carrier density, and defect densities of specific layers, as well as the interface defect density of specific interfaces. Various layers are optimized to enhance the overall performance of the PD and the impact of different device resistances is analyzed. The photocurrent (JSC) and voltage (VOC) of the heterostructure photodetector are determined to be 38.60 mA/cm2 and 1.0 V, in turn. The maximum responsivity (R) and detectivity (D*) are identified as 0.70 A/W and 4.60 × 1016 Jones, respectively at a wavelength of 940 nm. The spectral response exhibits significantly higher values in the range of 800–1000 nm, indicating the device's capability to detect near‐infrared (NIR) light. This research provides valuable insights for the manufacturing of AISe material‐based photodetectors with enhanced performance.

Among its many uses, graphene shows significant promise for optical and optoelectronic applications. In particular, devices based on the photothermoelectric effect (PTE) in graphene can offer a strong and fast photoresponse with a high signal-to-noise ratio while consuming minimal power. In this work, we discuss how to optimize the performance of graphene PTE photodetectors by tuning the light confinement, device geometry, and material quality. This study should prove useful for the design of devices using the PTE in graphene, with applications including optical sensing, data communications, multigas sensing, and others. ; ICN2 is supported by the Severo Ochoa Centres of Excellence program, funded by the Spanish State Research Agency (AEI, Grant No. SEV-2017-0706), and is funded by the CERCA program of the Generalitat de Catalunya. This work has received funding from the European Union's Horizon 2020 research and innovation program under Grant Agreement No. 825272 (ULISSES) and from the project "Waveguide-Integrated Mid-Infrared Graphene Detectors for Optical Gas Sensor Systems," Reference No. PCI2018-093128, funded by the Spanish Ministry of Science and Innovation - AEI.

The bioelectronics takes of the biology the optimized elements for to do a copy and to build technological mechanisms with functions based in that of body lives components. Telecommunications and biology present an analogy between the optical receivers and insects eyes, which forms are adequate to receipt signal since a transmitter, and these are been leaded to perfection by the nature during millions of years in the environment adaptation. The sizes and the forms depend of the direction of the waves and of the radiation pattern of these biotransmitters and bioreceivers (omatidies of insects eyes), which is similar as the optical communications emitters and photodetectors. The growth of the telecommunication services makes necessary the optimization of the bandwidth of the transmission channels. Although the optic transmission is considered like the ideal as for the attenuation and distortion characteristics that make that it possesses the better relation bandwidth - longitude, the demand of more transmission capacity forces to take advantage of them efficiently. High costs generated when deploying Optic Fiber Networks at the transport level, together with other factors that avoid PONs arriving to the home and/or office, have impulsed the design and implementation of partially optical networks (FITL), including an alternative that uses infrared light. This work explores the basis of these news access networks, and it is presented an optical communication transmission/reception system with optic channel of free space where has been modulated the transmitter laser through a set of spherical lens and optical fibers that expand the beam of light to different points of an indoor enclosure producing multiple punctual images located in positions that permit to determine and to optimize the bandwidth of the system. The computational simulation results are showed and are compared with those experimentally measured, indicating that this is an original method for to design emitters and receivers of high performance for optical communications.

Structural, electronic, optic and vibrational properties of Zinc antimonide (ZnSb) monolayers and their func-tionalized (semi-fluorinated and fully chlorinated) structures are investigated by means of the first-principles calculations. The phonon dispersion curves reveal the presence of imaginary frequencies and thus confirm the dynamical instability of ZnSb monolayer. The calculated electronic band structure corroborates the metallic character with fully-relativistic calculations. Moreover, we analyze the surface functionalization effect on the structural, vibrational, and electronic properties of the pristine ZnSb monolayer. The semi-fluorinated and fully-chlorinated ZnSb monolayers are shown to be dynamically stable in contrast to the ZnSb monolayer. At the same time, semi-fluorination and fully-chlorination of ZnSb monolayer could effectively modulate the metallic elec-tronic properties of pristine ZnSb. In addition, a magnetic metal to a nonmagnetic semiconductor transition with a band gap of 1 eV is achieved via fluorination, whereas a transition to a semiconducting state with 1.4 eV band gap is found via chlorination of the ZnSb monolayer. According to the optical properties analysis, the first ab-sorption peaks of the fluorinated-and chlorinated-ZnSb monolayers along the in-plane polarization are placed in the infrared range of spectrum, while they are in the middle ultraviolet for the out-of-plane polarization. Interestingly, the optically anisotropic behavior of these novel monolayers along the in-plane polarizations is highly desirable for design of polarization-sensitive photodetectors. The results of the calculations clearly proved that the tunable electronic properties of the ZnSb monolayer can be realized by chemical functionalization for application in the next generation nanoelectronic devices. ; National Research Foundation of Korea (NRF) - Korea government (MSIT) [NRF-2017R1A2B2011989]; Flemish Science Foundation (FWO-Vl)FWO [EXC 2122, 390833453] ; This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT)(NRF-2017R1A2B2011989). Computational resources were provided by the Flemish Supercomputer Center (VSC). M.Y. is supported by the Flemish Science Foundation (FWO-Vl) by a postdoctoral fellowship. (EXC 2122, Project ID 390833453).

Structural, electronic, optic and vibrational properties of Zinc antimonide (ZnSb) monolayers and their func-tionalized (semi-fluorinated and fully chlorinated) structures are investigated by means of the first-principles calculations. The phonon dispersion curves reveal the presence of imaginary frequencies and thus confirm the dynamical instability of ZnSb monolayer. The calculated electronic band structure corroborates the metallic character with fully-relativistic calculations. Moreover, we analyze the surface functionalization effect on the structural, vibrational, and electronic properties of the pristine ZnSb monolayer. The semi-fluorinated and fully-chlorinated ZnSb monolayers are shown to be dynamically stable in contrast to the ZnSb monolayer. At the same time, semi-fluorination and fully-chlorination of ZnSb monolayer could effectively modulate the metallic elec-tronic properties of pristine ZnSb. In addition, a magnetic metal to a nonmagnetic semiconductor transition with a band gap of 1 eV is achieved via fluorination, whereas a transition to a semiconducting state with 1.4 eV band gap is found via chlorination of the ZnSb monolayer. According to the optical properties analysis, the first ab-sorption peaks of the fluorinated-and chlorinated-ZnSb monolayers along the in-plane polarization are placed in the infrared range of spectrum, while they are in the middle ultraviolet for the out-of-plane polarization. Interestingly, the optically anisotropic behavior of these novel monolayers along the in-plane polarizations is highly desirable for design of polarization-sensitive photodetectors. The results of the calculations clearly proved that the tunable electronic properties of the ZnSb monolayer can be realized by chemical functionalization for application in the next generation nanoelectronic devices. ; National Research Foundation of Korea (NRF) - Korea government (MSIT) [NRF-2017R1A2B2011989]; Flemish Science Foundation (FWO-Vl)FWO [EXC 2122, 390833453] ; This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT)(NRF-2017R1A2B2011989). Computational resources were provided by the Flemish Supercomputer Center (VSC). M.Y. is supported by the Flemish Science Foundation (FWO-Vl) by a postdoctoral fellowship. (EXC 2122, Project ID 390833453). ; WOS:000626633500001 ; 2-s2.0-85099785475