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[IEEE 2018 IEEE 7th Global Conference on Consumer Electronics (GCCE) - Nara, Japan (2018.10.9-2018.10.12)] 2018 IEEE 7th Global Conference on Consumer Electronics (GCCE) - BER Performance Impaired by Transmission Time Offset between Users in Optical Wireless CSK/ACDMA System Using DMPOMs
摘要： An optical-wireless code-shift-keying (CSK) system utilizing dual modified pseudo orthogonal M-sequence sets (DMPOMs) has been proposed by authors. DMPOM is generated by merging modified pseudo orthogonal M-sequence sets (outer-code), bi-orthogonal code and orthogonal M-sequences (inner-code). In this paper, bit error rate (BER) of the optical-wireless CSK/asynchronous CDMA is investigated in 2-user communication. Consequently, for the realization of the CSK/CDMA, it is effective to utilize the inner codes generated by different feedback taps.
关键词： optical-wireless,bit error rate (BER),code-shift-keying (CSK),dual modified pseudo orthogonal M-sequence sets (DMPOMs),asynchronous CDMA (ACDMA)
更新于2025-09-04 15:30:14
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[Lecture Notes in Electrical Engineering] Engineering Vibration, Communication and Information Processing Volume 478 (ICoEVCI 2018, India) || Wavefunctions and Optical Gain in $$ \text{In}_{0.3} {\text{Ga}}_{0.7} {\text{As}}/{\text{GaAs}}_{0.4} {\text{Sb}}_{0.6} $$In0.3Ga0.7As/GaAs0.4Sb0.6 Type-II Double Quantum Well Nanoheterostructure Under External Uniaxial Strain
摘要： Variations in wavefunction con?nement under external uniaxial strain are observed to affect the optical gain obtained in type-II quantum well nanodimension heterostructures. This paper reports the wavefunctions and optical gain realized in In0.3Ga0.7As/GaAs0.4Sb0.6 type-II double QW heterostructure under uniaxial strain along [001]. Energy bands, wavefunctions of con?nement states in the structure and optical gain of the heterostructure under electromagnetic ?eld perturbation are presented. The 6×6 k·p Hamiltonian matrix is considered, and Luttinger–Kohn model has been applied for the electronic band structure calculations. Optical gain spectra of the double QW nanoheterostructure under external uniaxial strain of 1, 2 and 5 GPa, respectively, is calculated. The optical gain curve shows a signi?cant improvement in gain under external uniaxial strain along [001] at 300 K. For a charge carrier injection of 8 × 1012/cm2, the optical gain is 9170 in x polarization. The heterostructure is seen to be operating in the energy range of 0.65–0.8 eV (1549–1907 nm). Thus, a wide range wavelength tuning can be realized.
关键词： Heterostructure,InGaAs,GaAsSb,Optical gain,Type-II
更新于2025-09-04 15:30:14
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Combined mechanochemical/thermal annealing approach for the synthesis of Co9Se8 with potential optical properties
摘要： Synthesis of Co9Se8 phase from metallic cobalt and selenium powders by one-pot mechanochemical synthesis in a planetary ball mill and subsequent thermal treatment in argon atmosphere is reported. Crystal structure and morphology of the products were characterized by X-ray diffraction, specific surface area measurements, and transmission electron microscopy. Our study revealed that only mixture with excess of Co resulted in the formation of higher fraction of the Co9Se8 phase. While milling of Co and Se in 13.5:8 ratio resulted in the synthesis of nanocrystalline hexagonal CoSe (freboldite) and only around 13?wt.% of the targeted Co9Se8 phase, additional isothermal treatment at 450?°C increased yield of the Co9Se8 phase to more than 70%. Optical properties of the product with the highest Co9Se8 fraction showed broad absorption in whole UV–Vis optical region and band-gap energy of 1.93?eV, blue-shifted relative to the bulk Co9Se8. Both UV–Vis and photoluminescence spectra indicated quantum size effect of the finest nanocrystals in Co9Se8 product. The new combined approach represents a simple, fast, and easy up-scalable route for the synthesis of Co9Se8.
关键词： thermal annealing,optical properties,mechanochemical synthesis,Co9Se8,quantum size effect
更新于2025-09-04 15:30:14
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Passive Integrated Optical Gyroscope Based on Photonic Crystal Ring Resonator for Angular Velocity Sensing
摘要： In this paper, we investigated the concept of the Sagnac effect in passive integrated optical gyroscope base photonic crystal ring resonator for angular velocity sensing. This configuration utilizes one 3 dB coupler, two Bus waveguides, and five ring resonators for rotation sensing. The structure has been designed using dielectric silicon rods which are embedded in air. The transmission efficiency of the photonic crystal ring resonator at 1551 nm is about 96% with quality factor and bandwidth values equal to 4326 and 0.35 nm, respectively. By measuring the power of the output port, it is possible to estimate the phase shift and then to measure the rotation rate. The central wavelength of structure is assumed to be equal to 1569.9 nm. The structure characteristics have been investigated by using the two-dimensional finite-difference time-domain method. The footprint of the structure is approximately 279 μm2.
关键词： Photonic crystal,Angular velocity sensing,Ring resonator,Optical gyroscope
更新于2025-09-04 15:30:14
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Machine Learning for 100Gb/s/λ Passive Optical Network
摘要： To respond the growing bandwidth demand by emerging applications such as fixed-mobile convergence for 5G and beyond 5G, 100Gb/s/λ access network becomes the next research focus of passive optical network (PON) roadmap. Intensity modulation and direct detection (IMDD) technology is still considered as a promising candidate for 100Gb/s/λ PON attributed to its low cost, low power consumption and small footprint. In this paper, we achieve 100Gb/s/λ IMDD PON by using 20G-class optical and electrical devices due to its commercial linear and nonlinear availability. To mitigate the system distortions, neural network (NN) based equalizer is used and the performance is compared with feedforward equalizer (FFE) and Volterra nonlinear equalizer (VNE). We introduce the rules to train and test the data when using NN-based equalizer to guarantee a fair comparison with FFE and VNE. Random data has to be used for training, but for test, both random data and psudo-random bit sequence (PRBS) are applicable. We found NN-based equalizer has the same performance with FFE and VNE in the case of linear distortion only, but outperforms them in strong nonlinearity case. In the experiment, to improve the loss budget, we increase the launch power to 18 dBm, achieving a 30-dB loss budget for 33Gbaud/s PAM8 signal at the system frequency response of 16.2 GHz, attributed to the strong nonlinear equalization capability of NN.
关键词： neural network (NN),machine learning,intensity modulation and direct detection (IMDD),digital signal processing (DSP),Passive optical network (PON)
更新于2025-09-04 15:30:14
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Infrared Absorption Imaging of Water Ingress Into the Encapsulation of (Opto-)Electronic Devices
摘要： Water ingress into the encapsulation of electronic devices is a serious issue, especially for organic and perovskite-based electronics. In order to guide the development of suitable barrier materials and design, a reliable, fast, and non-destructive analysis tool is required. In this work, an imaging setup is presented, which is based on selective infrared (IR) radiation sources and a mid- IR sensitive camera that uses the absorption band of water around 1920 nm and a reference band. This system enables us to monitor the distribution of water concentration inside the packaging of devices and its change over time. Our measurement is capable of detecting the local presence of water down to the mg/m2 concentration range in a wide variety of encapsulation materials. The new tool allows identifying the pathways of moisture ingress into the encapsulation along with the corresponding diffusion coef?cient. Thus, it provides fast and reliable analysis of humidity related failure mechanisms, and consequently helps to improve the design of encapsulation materials and processes.
关键词： optical signal detection,Degradation,organic photovoltaics (PVs),packaging,diffusion processes
更新于2025-09-04 15:30:14
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SPR based fiber optic sensor using IMO thin film: towards wide wavelength tunability from visible to NIR
摘要： Due to existence of free electrons, conducting metal oxides (CMOs) such as indium molybdenum oxide, can support surface plasmon resonance (SPR) at the interface of CMO and the dielectric. This research provides first theoretically implementation of Indium molybdenum oxide (IMO) as plasmonic layer in SPR fiber optic sensor. We demonstrate how changing the oxygen contents during IMO layer deposition could tune the operational wavelength of sensing probe in a wide range from visible to NIR which has a great significance in many biological and chemical environmental applications. Moreover, sensitivity and figure of merit of the proposed sensor have been calculated and compared for IMO thin films prepared at different oxygen contents.
关键词： Surface plasmon resonance,Indium molybdenum oxide,Optical fiber sensors,Wide wavelength tunability,Figure of merit,Sensitivity
更新于2025-09-04 15:30:14
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Optical temperature sensor based on Sm3+ emissions in a fluorotellurite glass
摘要： The temperature dependence of the visible luminescence of a fluorotellurite glass doped with 2.5 mol% of Sm3+ ions was studied in order to use it as a high temperature sensing probe. For this purpose, the emission intensities of the levels from 4G5/2 to 6HJ (J = 5/2, 7/2, 9/2, 11/2) transitions were measured in a temperature range from 300 up to 650 K. The changes in the emission profiles were calibrated by means of the fluorescence intensity ratio technique. The maximum temperature value obtained for the thermal sensibility was 640 K which is in the range of other matrix glasses. The calibration curve was done by fitting the intensity ratio between the different peak emissions. Finally, a schematic design for the Sm3+ optical temperature sensor is presented and the calculations of the sensitivity have been obtained. In addition, the fluorotellurite glass has been structural characterized by SEM-EDX, Raman Spectroscopy and XRD in order to infer the local environment of Sm3+ ions. Furthermore, the Judd-Ofelt parameters have been calculated from the absorption spectra and derived branching ratios and transition probabilities have been computed as well.
关键词： Material characterization,Sm3+,Thermal sensitivity,Fiber optical temperature sensor,Tellurite glass
更新于2025-09-04 15:30:14
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Using NMR Relaxometry to Probe Yb <sup>3+</sup> – Er <sup>3+</sup> Interactions in Highly Doped Nanocrystalline NaYF <sub/>4</sub> Nanostructures
摘要： Solid–state nuclear magnetic resonance (NMR) spectroscopy is used to study heavily Yb3+ and Er3+ doped, fluorescent NaY1–x–yYbxEryF4 nanoparticles. An understanding of the 19F wide line NMR response suggests that the 0 ppm portion of the 19F NMR spectrum can be used as a probe of trivalent lanthanide content via spin lattice relaxation time changes. A Yb3+ and Er3+ magnetic interaction is manifest as a cooperative contribution to the 19F spin lattice relaxation rate in heavily co–doped nanoparticle samples. The results from this study will help understand the mechanism of enhanced optical up–conversion among these well–known nanostructures.
关键词： Solid–State NMR,Yb3+ – Er3+ Interactions,Nanocrystalline NaYF4,Optical Up–Conversion,NMR Relaxometry
更新于2025-09-04 15:30:14
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[IEEE 2018 15th International Multi-Conference on Systems, Signals & Devices (SSD) - Yassmine Hammamet, Tunisia (2018.3.19-2018.3.22)] 2018 15th International Multi-Conference on Systems, Signals & Devices (SSD) - The New Candidate Materials for Infrared Optical Devices
摘要： In this study, We propose the cubic AlxB1-xBi ternary alloy as a promising infrared material. We used the full potential-linearized augmented plane wave (FP-LAPW) method within the Density Functional Theory (DFT) to predict the structural and electronic properties of the AlxB1-xBi ternary alloys. The structural properties such as the equilibrium lattice parameter, bulk modulus, and its pressure derivative are investigated with the effect of the concentration variation of Al atom, x (x=0, 0.25, 0.50, 0.75 and 1). We found that the equilibrium lattice parameter of AlxB1-xBi ternary alloys increases when increasing the doping concentration of the Al atom, while its bulk modulus decreases. The energy band gap of the AlxB1-xBi ternary alloys decreases with the increase in the Al doping concentration. The AlxB1-xBi alloys for 0.50 and 0.75 present a semi-metallic character the other concentrations and are compositions. Our results show the direct nature of the energy band gap of the ternary AlxB1-xBi alloy for all composition of Al substitution. To our knowledge, this is the first theoretical study of this ternary alloy that needs eventual experimental data for confirmations.
关键词： Optical properties,TB-MBJ,FP-LAPW,Electronic structure,GGA,DFT,Infrared Radiation,III-III-V ternary Alloy
更新于2025-09-04 15:30:14