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Electrochemical behaviour and analytical applications of a manganese porphyrin a?? silica hybrid film prepared by pulsed laser deposition
摘要： Hybrid nanomaterials can have superior properties in comparison with individual components, sometimes greatly improving their optoelectronic activity. For this reason, modified carbon electrodes were obtained using a hybrid material composed of 5,10,15,20-tetra(4-tolyl)porphyrinato manganese (III) chloride (MnTTP) embedded in a silica matrix. The laser ablation deposition technique (PLD) has been used to immobilize the manganese porphyrin–silica hybrid on the surface of the carbon electrodes. The successful transfer of the manganese-porphyrin was evidenced by UV–Vis absorption spectroscopy. The PLD-deposited hybrid film was characterized using AFM and electrochemical methods (cyclic voltammetry and square wave voltammetry). The viability of this hybrid nanomaterial film as a redox mediator for the anodic oxidation and sensitive voltammetric determination of ascorbic acid in buffer solution (pH = 6.5) is described. The recorded anodic process is attributed to its oxidation to dehydroascorbic acid, with satisfactory catalytic current response and low non-Faradaic current.
关键词： Mn-porphyrin,Silica matrix,Hybrid nanomaterial,Pulse laser deposition,Electrocatalytic film,Ascorbic acid
更新于2025-09-19 17:13:59
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[IEEE 2019 Photonics North (PN) - Quebec City, QC, Canada (2019.5.21-2019.5.23)] 2019 Photonics North (PN) - Progress in Passively Mode-Locked 2-Micron Tm and Ho Bulk Solid-State Lasers
摘要： The increasing number of computational servers in data centers is imposing tighter constraints on the networking infrastructure. Scalable power efficient optical interconnect network becomes necessary to leverage the bandwidth capacity of current electronic switches or opto-electronic components. Hence, novel optical interconnect technology can enhance the network capacity by harnessing the feasibility of simultaneous processing of optical signal in the wavelength and time domains. In this paper, we present a four channel optical passive wavelength-striped mapping (PWSM) device, which passively time compresses/expands serial packets through optical wavelength multiplexing/demultiplexing. The PWSM device, which has a 1 × 4 channel optical wavelength demultiplexer with integrated optical delay lines, is designed in a low-loss Si3N4 (propagation loss ～3.1 dB/m) waveguide platform. The PWSM device multiplexes/demultiplexes four WDM channels and offsets in time the adjacent channels to optically serialize/deserialize data packets. In this demonstration, a 64 ns long data packet is formed at the output of the device by combining four 16 ns data segments of the packet in time domain. Incremental optical insertion loss between adjacent channels is ～9.7 dB due to the integrated passive optical delay waveguides. The data rate of the four segmented packets and the combined packet is 25 Gb/sec. We have measured a bit error rate performance below 1 ×10?9 for the 64 ns serial data packet regenerated by the PWSM device for a received optical power of –6.7 dBm.
关键词： silica and silicon nitride photonics,wavelength filtering devices,Photonic integrated circuits
更新于2025-09-19 17:13:59
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Low-Loss Waveguides by Planar Modified Chemical Vapor Deposition
摘要： We present a novel method to fabricate planar photonic devices for high power applications using Modified Chemical Vapor Deposition (MCVD) technology. The MCVD process, usually applied to optic fibers, is used here to deposit a layer of Ge doped silica on a fused silica slab. The doped layer was then heat-treated by a CO2 laser in order to achieve high optical quality and increase its damage threshold. Finally, direct laser lithography, followed by deep dry etching, was used to shape straight and curved large-core air-cladded waveguides with smooth sidewalls. The straight waveguides were shown to have an excellent propagation loss, 0.33 dB/cm, and the curved waveguide had a propagation loss of 1 dB/cm.
关键词： Propagation losses,Optical waveguides,Germanium doped silica
更新于2025-09-16 10:30:52
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A photovoltaic stand-alone lighting system with polymeric-silica-gel-electrolyte-based substrate-integrated lead-carbon hybrid ultracapacitors
摘要： Harnessing solar electricity generated through photovoltaic cells with lead-acid batteries remains the most compelling option at present. But lead-acid batteries have encountered problems in photovoltaic installations, mainly due to their premature failure. To circumvent the aforesaid problem, a new technology referred to as substrate-integrated lead-carbon hybrid ultracapacitor with polymeric-silica-gel electrolyte, is developed in-house and tested for solar-electricity storage for a lighting application. The high-throughput performance tests for the device are conducted at laboratory scale and compatibility of the device for photovoltaic application is evaluated. In doing so, the device is installed with a photovoltaic panel for field test and data are collected from August 2012 through July 2013. The year round field-test data analyzed in the light of the available global-horizontal-irradiance data show attractive performance for the device. It is noteworthy that, unlike lead-acid batteries, seasonal variations in solar radiance exhibit little effect on the performance of the device.
关键词： Polymeric silica gel electrolyte,Cycle-life,Photovoltaic application,Substrate-integrated lead-carbon hybrid ultracapacitor,Field testing
更新于2025-09-16 10:30:52
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Novel Gd3+-doped silica-based optical fiber material for dosimetry in proton therapy
摘要： Optical fibers hold promise for accurate dosimetry in small field proton therapy due to their superior spatial resolution and the lack of significant Cerenkov contamination in proton beams. One known drawback for most scintillation detectors is signal quenching in areas of high linear energy transfer, as is the case in the Bragg peak region of a proton beam. In this study, we investigated the potential of innovative optical fiber bulk materials using the sol-gel technique for dosimetry in proton therapy. This type of glass is made of amorphous silica (SiO2) and is doped with Gd3+ ions and possesses very interesting light emission properties with a luminescence band around 314 nm when exposed to protons. The fibers were manufactured at the University of Lille and tested at the TRIUMF Proton Therapy facility with 8.2–62.9 MeV protons and 2–6 nA of extracted beam current. Dose-rate dependence and quenching were measured and compared to other silica-based fibers also made by sol-gel techniques and doped with Ce3+ and Cu+. The three fibers present strong luminescence in the UV (Gd) or visible (Cu,Ce) under irradiation, with the emission intensities related directly to the proton flux. In addition, the 0.5 mm diameter Gd3+-doped fiber shows superior resolution of the Bragg peak, indicating significantly reduced quenching in comparison to the Ce3+ and Cu+ fibers with a Birks’ constant, kB, of (0.0162 ± 0.0003) cm/MeV in comparison to (0.0333 ± 0.0006) cm/MeV and (0.0352 ± 0.0003) cm/MeV, respectively. To our knowledge, this is the first report of such an interesting kB for a silica-based optical fiber material, showing clearly that this fiber presents lower quenching than common plastic scintillators. This result demonstrates the high potential of this inorganic fiber material for proton therapy dosimetry.
关键词： Bragg peak,dosimetry,Gd3+-doped silica,optical fibers,quenching,sol-gel technique,proton therapy
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Lasing and Gain Properties of Multicomponent Optical Fibers with Heavily Er-Doped Phosphate Core and Silica Cladding
摘要： The most common Er-doped fibres being used today are silica-based. However solubility limit of erbium ions in silica glass restrict shortening of the gain medium in fibre light sources and that way, it limits improving single-frequency fibre lasers, amplifiers and pulsed fibre lasers characteristics. Shortening of a fibre gain medium might be successfully realised by using high-concentration Er-doped phosphate glasses. It was shown that such type of glass allows getting rare-earth ions concentration an order of magnitude higher in comparison with silica glasses without ions clusterization [1]. But significant drawbacks of phosphate fibres are their low corrosion resistance and high losses of its fusion splices with standard silica fibres [2]. The main purpose of our work was an investigation of fibre light sources based on novel multicomponent fibre with 3wt.% Er-doped phosphate core and silica cladding, which take advantages of both phosphate and silica glasses.
关键词： phosphate core,Er-doped fibres,silica cladding,multicomponent fibre,fibre light sources
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Analysis of Various Approaches for the Fabrication of Diffractive Optical Elements
摘要： Diffractive Optical Elements (DOEs) exist for a large range of applications. Usually DOEs are obtained by combining lithographic techniques and etching in order to achieve pre-determined phase patterns. That way, it is possible to shape or split laser beams with very high efficiencies. Indeed for binary element which consist of two phase levels (0 and π) the diffraction efficiency is around 75% and this efficiency can approach 100% for multilevel elements. Various illustrations of DOEs can be found in the literature for example using organic materials like photoresists or inorganic materials such as silica or chalcogenide layers. Recent work has shown that DOEs can also be recorded in the volume of photosensitive chalcogenide layers, but no precise comparison of this class of DOEs has ever been made with classical DOEs. In this paper we propose to study binary DOEs fabricated with conventional lithography (based on local control of the thickness) and similar one fabricated using photo-induced refractive index change in As2S3 layers.
关键词： etching,phase patterns,silica,laser beams,photo-induced refractive index change,photoresists,lithography,As2S3 layers,chalcogenide layers,Diffractive Optical Elements,diffraction efficiency
更新于2025-09-16 10:30:52
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Coupled Thermal-Mechanical Analysis of CO<sub>2</sub> Laser Irradiation on Fused Silica
摘要： To grind fused silica in ductile mode, it was proposed to repair surface and subsurface micro cracks of fused silica by CO2 laser irradiation. However, excessive residual stress remains on the surface because the melt fused silica on the surface quenches in air. It causes the critical depth of cut for ductile grinding fused silica to be smaller than 0.2μm. To investigate the distribution of the residual stress and look for an optimal manner of irradiation to control residual tensile stress, a numerical model of was built for simulating the dynamic behavior of fused silica when irradiated by CO2 laser. Laser energy absorption, heat transmission, viscoelastic behavior of fused silica and thermally induced stress were considered in the numerical simulation. The results show how the residual stress is formed and distributed. We found that an appropriate control of the temperature field as a function of time and position in the laser process is the key to reduce the residual stress. Therefore, three kinds of processes were proposed to reduce residual tensile stress on the surface of fused silica introduced by laser irradiation. The residual stress distributions of these three processes were compared by numerical analysis to decide a better method of laser irradiation.
关键词： fused silica,laser irradiation,ductile grinding,viscoelastic,residual stress
更新于2025-09-16 10:30:52
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A quantum dot-silica composite as an efficient spectral converter in a luminescent down-shifting layer of organic photovoltaic devices
摘要： We developed a gradient quantum dot (QD)@polyvinylpyrrolidone (PVP)-silica composite as a spectral converter to improve light harvesting of the photoactive layer in organic photovoltaic (OPV) devices. The spectral converter prepared by a simple sol–gel method served as a luminescent down-shifting (LDS) layer that absorbed ultraviolet and emitted visible light. Re-emitted light energy from the LDS layer appeared within the absorption range of the photoactive donor material of P3HT in the OPV devices. We investigated how the light harvesting ability was affected by the concentration of QD@PVP and the thickness of the LDS layer. The OPV devices with the LDS layer showed increased power conversion efficiency (PCE) from 3.38% to 3.68% compared to pristine OPV devices due to improved incident light transmittance and increased light harvesting.
关键词： spectral converter,organic photovoltaic devices,silica composite,quantum dot,luminescent down-shifting
更新于2025-09-16 10:30:52
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Tm/Al co-doped silica glass prepared by laser additive manufacturing technology for 2 μm photonic crystal fiber laser
摘要： In this work, we demonstrated the Tm/Al co-doped silica glass fabricated by the laser additive manufacturing technology for the first time. The measurements show that the glass was doped with Tm3+ concentration of 1.64 wt% without any crystallization. The Tm3+ and Al3+ were uniformly distributed and no additional defects were introduced during the fabrication process. The glass exhibits low hydroxyl content level of 11.56 ppm. Using the prepared silica glass as the core rod, a Tm/Al co-doped photonic crystal fiber (PCF) was fabricated and performed 13.9 % slope efficiency with nearly 600 mW output laser power. This novel technology provides an alternative method to fabricate Tm-doped fiber materials with high homogeneity and large core size, promoting the further spread and development of 2 μm fiber lasers.
关键词： Tm-doped fiber,silica glass,laser additive manufacturing,photonic crystal fiber
更新于2025-09-16 10:30:52