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oe1(光电查) - 科学论文

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出版时间
  • 2019
研究主题
  • Distributed optical fiber sensing
  • Optical frequency domain reflection
  • Polynomial regression algorithm
  • Nonlinear tuning compensation
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Hebei University of Technology
333 条数据
?? 中文（中国） ▾

  • The Critical Adiabatic Linear Tapered Waveguide Combined with a Multimode Waveguide Coupler on an SOI Chip

    摘要： A multimode waveguide interference (MMI) coupler is combined with a critical linear tapered waveguide on a silicon-on-insulator (SOI) chip. When the TE0 mode is a critical adiabatic mode conversion from a single-mode waveguide to an extreme linear tapered waveguide combined with an MMI, this linear tapered waveguide is achieved to the maximum divergence angle (i.e., the shortest length). The maximum divergence angle is expressed by θ ≤ 2 tan? 1[(0.35Wmmi ? Ws)/(0.172Lmmi)] under a 1 × 1 MMI combined with this critical linear tapered waveguide. The expression formula is demonstrated by three di?erent widths of a 1 × 1 MMI of 4 μm/8 μm/12 μm combined with the critical linear tapered waveguide. So, the maximum divergence angle is obtained at θ ? 16°/14°/8°, with respect to this linear tapered waveguide loss of 0.022 dB/0.172 dB/0.158 dB, and this linear tapper length is reduced by 93.7%/92.9%/87.5% than the divergence angle θ ? 1°. The output power of a 1 × 1 MMI combined with a critical linear tapered waveguide is enhanced at least 1.5 times under 0.95 above condition.

    关键词： multimode waveguide interference (MMI) coupler,TE0 mode,linear tapered waveguide,silicon-on-insulator (SOI) chip,adiabatic mode conversion

    更新于2025-09-12 10:27:22

  • Investigation of LED Non-linearity on DCO-OFDM and ACO-OFDM in VLC Systems using Multichip RGB LEDs for Indoor Applications

    摘要： The impact of the LED non-linearity on the Intensity Modulation Direct Detection (IM-DD) in the VLC using OFDM for white light generated using RGB LEDs for indoor applications is analyzed. This work extends the orders of harmonics for analysis and investigates the impact of this non-linearity issue on OFDM techniques. The wavelengths (Red, Green and Blue) are individually set at the LED and their induced photocurrent in a Si PD is calculated. The result shows that the wavelength corresponding to the 625nm induces 5dB and 3dB more power than 528nm and 458nm respectively. We choose 625nm as the OFDM signal carrier for transmission keeping the other two un-modulated. We compare the effects of the non-linearity of the LED on the two OFDM techniques- Asymmetrical clipped optical (ACO) and Direct current biased optical (DCO). Our simulation results show that the power of the 2nd and 3rd order intermodulation components for ACO-OFDM is 3dB lesser than DCO-OFDM. The required SNR for ACO-OFDM is found to be 3dB lesser as compared to DCO-OFDM. The clipping effect of the LED remains unchanged irrespective of the OFDM variation applied.

    关键词： Visible Light Communication,White Light,ACO-OFDM,LED,DCO-OFDM,Non-Linear Distortion

    更新于2025-09-12 10:27:22

  • Fabrication of fine wires using direct laser melting process

    摘要： With the rapid development of micro electro-mechanical-systems and micro system technology, parts made of micro-wire are widely applied in biomedical, automotive, and consumer electronics. Therefore, the manufacturing of micro-wire has played an important role in manufacturing micro parts. However, when dimensions of metal parts downscale to micro scale, the plastic deformation behaviors and thermal properties which dependent on the specimen size are different from those in the macro scale, and size effects occur. The direct laser melting process can directly build full-density, high-performance, complex metal parts by melting metal powder with laser scanning. This study investigated the direct laser melting method to fabricate fine linear-bead that can be potentially substituted for micro-wire has been investigated. Laser process parameters, such as laser power, laser scanning speed, powder grain size and powder layer thickness were found to be an important variable affecting shape of linear-bead. Surface shape and cross-sectional properties were analyzed using microscope and hardness tester.

    关键词： Direct laser melting (DLM),Linear-bead,Hardness,Roundness

    更新于2025-09-12 10:27:22

  • Direct observation and simultaneous use of linear and quadratic electro-optical effects

    摘要： We report on the direct observation and simultaneous use of the linear and quadratic electro-optical effect and propose a method by which higher-order susceptibilities of electro-optical materials can be determined. The evaluation is based on the separation of the second- and third-order susceptibilities and the experimental technique uses a slot waveguide ring resonator fabricated in an integrated photonic circuit technology, which is embedded by a guest-host polymer system consisting of the azobenzene dye disperse red 1 in a poly(methyl methacrylate) matrix as active electro-optical material. The contribution of both effects on the electro-optical response under the influence of static and time-varying electrical fields is investigated. We show that the quadratic electro-optical effect has a significant influence on the overall electro-optical response even with acentric molecular orientated molecules. Our findings have important implications for developing electro-optical devices based on polymer-filled slot waveguides and give rise to advanced photonic circuits.

    关键词： higher-order susceptibilities,electro-optical materials,quadratic electro-optical effect,slot waveguide,ring resonator,linear electro-optical effect

    更新于2025-09-12 10:27:22

  • Site-selective Atomic Layer Precision Thinning of MoS2 via Laser-Assisted Anisotropic Chemical Etching

    摘要： Various exotic optoelectronic properties of two-dimensional (2D) transition metal dichalcogenides (TMDCs) strongly depend on their number of layers, and typically manifest in ultra-thin few- or mono-layer formats. Thus, precise manipulation of thickness and shape is essential to fully access their potential in optoelectronic applications. Here, we demonstrate site-selective atomic layer precision thinning of exfoliated MoS2 flake by laser. The oxidation mediated anisotropic chemical etching initiated from edge defects and progressed by controlled scanning of the laser beam. Thereby, the top-most layer can be preferentially removed in designed patterns without damaging the bottom flake. In addition, we could monitor the deceleration of the thinning by in-situ reflectance measurement. The apparent slow-down of the thinning rate is attributed to the sharp reduction in the temperature of the flake due to thickness dependent optical properties. Fabrication of monolayer stripes by laser thinning suggests potential applications in non-linear optical gratings. The proposed thinning method would offer a unique and rather straightforward way to obtain arbitrary shape and thickness of TMDCs flake for various optoelectronic applications.

    关键词： Laser Thinning,Single layer precision thinning,Non-linear optical grating,Anisotropic chemical etching,TMDCs,MoS2

    更新于2025-09-12 10:27:22

  • Polarization of fluorescence radiation following electron impact excitation of ions immersed in strongly coupled plasmas

    摘要： An investigation on the electron impact excitation and subsequent radiative decay process of He-like Fe24t ions immersed in strongly coupled plasmas is made, using the 1s2p 3;1P1 ! 1s2 1S0 characteristic lines as an example. The shielded nuclear potential of the uniform electron gas model (UEGM) type experienced by the electron is parameterized by the ion-sphere radius. For the target structure, accuracies of wave functions are justified by evaluating the energies of the relevant states. To serve as an independent check of the results, self-consistent calculations are carried out using the multiconfiguration Dirac-Fock relativistic configuration interaction method incorporating the same potential. For the impact excitation process, the UEGM potential is also employed to screen the projectile electron from the nucleus and target electrons. A distorted-wave method in the framework of the relativistic theory is developed to include the effect of plasma background, in which the continuum wave function of the projectile electron is evaluated by solving numerically the modified Dirac equations. The plasma effects on the total excitation cross section, magnetic sublevel cross section, and linear polarization of fluorescence radiation are investigated. The comparison with the available theoretical and experimental results is satisfactory.

    关键词： UEGM potential,linear polarization,He-like Fe24t ions,electron impact excitation,strongly coupled plasmas,radiative decay

    更新于2025-09-12 10:27:22

  • A general time-domain formulation of equation-of-motion coupled-cluster theory for linear spectroscopy

    摘要： A time-dependent (TD) formulation of equation-of-motion (EOM) coupled-cluster (CC) theory is developed, which, unlike other similar TD-EOM-CC approaches [D. R. Nascimento and A. E. DePrince III, J. Chem. Theory Comput. 12, 5834–5840 (2016)], can be applied to any type of linear electronic spectroscopy. The TD-EOM-CC method is formally equivalent to the standard frequency-domain formulation of EOM-CC theory, with a potential computational advantage of a comparatively low memory footprint. This general TD-EOM-CC framework is applied to the linear absorption and electric circular dichroism spectra of several small oxirane derivatives.

    关键词： electronic circular dichroism,linear spectroscopy,equation-of-motion,time-dependent,coupled-cluster theory

    更新于2025-09-12 10:27:22

  • AIP Conference Proceedings [AIP Publishing RECENT TRENDS IN PURE AND APPLIED MATHEMATICS - Vellore, India (13–15 December 2018)] RECENT TRENDS IN PURE AND APPLIED MATHEMATICS - Non-linear optical properties of carbazole based dyes modified with diverse spacer units for dye-sensitized solar cells: A first principle study

    摘要： Density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations were performed for evaluating the photophysical and photochemical properties of a sequence of carbazole based metal-free organic dyes modified using different π-conjugation spacer units, such as thiopine, pyrrole, furan, thiazole and isoxazole. Moreover, the modified dyes were subjected to investigation towards their non-linear optical (NLO) features. The results revealed that dipole moment (μ), static polarizability (α), anisotropic polarizability (?α) and hyperpolarizability (first order (β) and second order (γ)) of modified dyes are considerably enhanced as a consequence of changing the spacer unit. Likewise, light harvesting efficiency and oscillator strength of the modified dyes are enhanced upon wavelength of absorption is red-shifted by influence of spacer moieties. We believe that our calculations provide a more profound physical perception on structural property relationship for carbazole based dyes and give a hint to create potential sensitizers for opto-electronic and dye-sensitized solar cell applications.

    关键词： dyes,DFT,carbazole,TDDFT,non-linear optical properties,dye-sensitized solar cells

    更新于2025-09-12 10:27:22

  • Classification of Ceramic Tableware by Laser Induced Breakdown Spectroscopy and Chemometrics

    摘要： Ceramics manufactured in Brazil and in other countries were analyzed by laser induced breakdown spectroscopy (LIBS). The LIBS spectra were employed to identify the origin of the tableware as produced in Brazil or abroad using soft independent modeling of class analogy (SIMCA) and linear discriminant analysis (LDA). Three sets of spectral variables were evaluated aiming at discrimination of the ceramics: the entire LIBS spectrum, a set of selected spectral ranges, and the maximum of emission intensity of the elements Al, Ca, Mg, Si, Na and Ti. The results for the three sets of variables show good performance, achieving correct classification from 88.6 to 94.3%, and 86.7 to 100% for the external training and test, respectively.

    关键词： laser induced breakdown spectroscopy (LIBS),chemometrics,soft independent modeling of class analogy (SIMCA),linear discriminant analysis (LDA),Ceramic tableware classification

    更新于2025-09-12 10:27:22

  • [IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Linear Analyses of A 0.22 THz Confocal Waveguide Gyro-TWT

    摘要： Confocal waveguide gyrotron traveling wave tube (gyro-TWT) is a novel gyrotron amplifier which can operate in higher order modes and generate high power. In this paper, the linear theory derived from kinetic theory is presented to analyze a 0.22-THz confocal waveguide Gyro-TWT which operates at HE06 mode. The linear gain is 9.6 dB/cm at 220.2 GHz. Different parameters are pointed out to show their influences on critical current of absolute instability.

    关键词： Gyro-TWT,confocal waveguide,linear theory

    更新于2025-09-12 10:27:22