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Polarization-controlled and single-transverse-mode vertical-cavity surface-emitting lasers with eye-shaped oxide aperture
摘要： We presented a single-transverse-mode and single-polarization vertical-cavity surface-emitting laser (VCSEL) with an eye-shaped oxide aperture, obtained by enhanced anisotropic oxidation of oxide layer. For apertures with dimensions of 2 ' 4.6 and 3 ' 6 μm2, the orthogonal polarization suppression ratio (OPSR) of the VCSEL was 22 and 19 dB, respectively. A single-mode suppression ratio (SMSR) of more than 25 dB at an output power of 0.5 mW was also achieved for the VCSEL with aperture dimension of 2 ' 4.6 μm2. We believe that the proposed method to realize the mode and polarization control of VCSELs has great potential in future applications. ? 2018 The Japan Society of Applied Physics
关键词： anisotropic oxidation,single-transverse-mode,VCSEL,single-polarization,eye-shaped oxide aperture
更新于2025-11-28 14:24:03
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Investigation on the crack fracture mode and edge quality in laser dicing of glass-anisotropic silicon double-layer wafer
摘要： This work puts forward numerical and experimental investigations on laser dicing of glass-anisotropic single-crystal silicon double-layer wafer using laser induced thermal-crack propagation (LITP). A semiconductor continuous wave laser working at the defocusing mode serves as volumetric heat source for glass layer while as surface heat source for silicon layer. Based on the classical fracture theory, a static seam-type crack is introduced under the circumstance of ABAQUS to simulate the crack fracture modes in glass layer as well as silicon layer with crystal planes of (100), (110) and (111) during laser dicing in different dicing directions. In the experiments, processing parameters are kept the same as the simulations and typical dicing directions obtained from simulations are also used. The surface morphologies of crack edges are measured by the optical microscope and surface profiler. Through the comparison of numerical and experimental results it is discovered that for the specific substrate, the evolution of crack edge qualities in different dicing directions and different layers can be interpreted based on the corresponding stress distribution and stress intensity factor (SIF) ratio explicitly. And most important of all, the anisotropy of silicon layer has significant influence on the fracture mode and edge quality of crack in both layers.
关键词： Crack fracture mode,Laser induced thermal-crack propagation,Glass-anisotropic single-crystal silicon double-layer wafer,Crack edge quality,Static seam-type crack
更新于2025-11-21 11:24:58
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Visible-Light Plasmonic Enhancement of Catalytic Activity of Anisotropic Silver Nanoparticles
摘要： Synthesis of silver nanoparticles (AgNPs) in presence of copper salt (as the etchant) led to the formation of nanoparticle samples with different fractions of anisotropic particles. The proportion of anisotropic nanoparticles decreased with increase in ratio of precursor Cu salt in the preparation protocol. These AgNPs samples were found to catalyse p-nitrophenol reduction by glycerol and Fenton oxidation of methyl orange. The catalytic activity of these AgNPs samples for these reactions increased with the fraction of anisotropic nanoparticles in the catalyst samples. On conducting these reactions under cool white LED visible light, the catalytic activity of AgNPs catalyst samples increased by 2 to 3 times compared to that observed in dark. The photo-Fenton MO degradation catalytic activity obtained is among the best reported in literature. However, the order of the reaction did not change whether the reaction was conducted under visible light or in dark. Direct plasmonic catalytic mechanisms are proposed to explain the enhancement in reactivity under visible light.
关键词： Plasmonic Photocatalysis,Visible Light,Anisotropic Silver Nanoparticles
更新于2025-11-19 16:56:42
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A Facile Approach for Fabricating Microstructured Surface Based on Etched Template by Inkjet Printing Technology
摘要： Microstructures are playing an important role in manufacturing functional devices, due to their unique properties, such as wettability or ?exibility. Recently, various microstructured surfaces have been fabricated to realize functional applications. To achieve the applications, photolithography or printing technology is utilized to produce the microstructures. However, these methods require preparing templates or masks, which are usually complex and expensive. Herein, a facile approach for fabricating microstructured surfaces was studied based on etched template by inkjet printing technology. Precured polydimethylsiloxane substrate was etched by inkjet printing water-soluble polyacrylic acid solution. Then, the polydimethylsiloxane substrate was cured and rinsed, which could be directly used as template for fabricating microstructured surfaces. Surfaces with raised dots, lines, and squares, were facilely obtained using the etched templates by inkjet printing technology. Furthermore, controllable anisotropic wettability was exhibited on the raised line microstructured surface. This work provides a ?exible and scalable way to fabricate various microstructured surfaces. It would bring about excellent performance, which could ?nd numerous applications in optoelectronic devices, biological chips, microreactors, wearable products, and related ?elds.
关键词： inkjet printing,microstructured surface,anisotropic wettability,etched template
更新于2025-11-14 15:27:09
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Precursor-reforming strategy induced g-C3N4 microtubes with spatial anisotropic charge separation established by conquering hydrogen bond for enhanced photocatalytic H2-production performance
摘要： Precursor-reforming strategy induced graphitic carbon nitride (g-C3N4) with different morphologies for enhanced photocatalytic hydrogen (H2) evolution activity is highly desirable. Herein, g-C3N4 microtubes (mg-C3N4) with adjustable closure degree of microtube orifice and spatial anisotropic charge separation are established by conquering hydrogen bond during thermally exfoliate precursor. Compared to the bulk g-C3N4 (bg-C3N4) and ultrathin g-C3N4 (ug-C3N4), the tubular structure endows mg-C3N4 with spatial anisotropic charge separation that accelerates transfer of charge carriers. As expected, the photocatalytic H2 evolution (PHE) activity of mg-C3N4 has been obviously enhanced. Particularly, the mg-C3N4-24 shows the best PHE activity (957.9 μmol h-1g-1), which is over 18.72 and 3.77 times higher than the bg-C3N4 and ug-C3N4, respectively. In addition, selective photo-deposition experiment results reveal a charge carriers migration behavior that photoproduction electrons migrate to the outer shell and holes prefer to move onto the inner shell of mg-C3N4, thus achieving efficient spatial anisotropic charge separation. We firmly believe that the work presents significant advancement for the design of other materials by precursor-reforming strategy.
关键词： Charge carriers,Precursor-reforming,mg-C3N4,Spatial anisotropic,PHE
更新于2025-11-14 15:23:50
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Scattering Effect Contributions to the Directional Canopy Emissivity and Brightness Temperature Based on CE-P and CBT-P Models
摘要： The directional anisotropy of canopy emissivity and brightness temperature in the thermal infrared band has widely been studied. However, the contribution of different scattering orders has been an open scientific question for many years. The recently proposed CE-P model enables us to analytically evaluate the different scattering orders. Herein, we derive expressions for the first double collisions (DCE12) and first triple collisions (DCE123). Our result shows that DCE123 can simulate the observed emissivity with an error less than 0.001 and that DCE12 is reasonably accurate when leaf emissivity is greater than 0.96. Numerical analysis shows that the contribution of quadruple or greater collisions can be ignored when the leaf (soil) emissivity is no less than 0.90. Furthermore, we develop the CBT-P model to simulate the directional brightness temperature (DBT) based on the new optimized CE-P model (DCE123) and validate it by 4SAIL (4-Stream Radiative Transfer Theory of Scattering by Arbitrary Inclined Leaves) and DART (Discrete Anisotropic Radiative Transfer) models. Both of isothermal (soil temperature is equal to leaf temperature) and nonisothermal (soil temperature is higher than leaf temperature) cases are considered. The maximum differences between the CBT-P model and 4SAIL (DART) are less than 0.35 K (0.42 K), the average differences between CBT-P and 4SAIL (DART) are less than 0.10 K (0.13 K), and the R2 is over 0.99 (0.95) with component emissivities larger than 0.90 and the difference between soil and leaf temperatures less than 20 K. The directional anisotropy of DBT is dominated by the zero-scattering and the single scattering terms according to the new developed CBT-P model.
关键词： directional canopy emissivity (DCE),CBT-P,Discrete Anisotropic Radiative Transfer (DART),4-Stream Radiative Transfer Theory of Scattering by Arbitrary Inclined Leaves (4SAIL),CE-P,directional brightness temperature (DBT)
更新于2025-09-23 15:23:52
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Vectorial perturbation theory for axisymmetric whispering gallery resonators
摘要： We propose a vectorial perturbation theory for axially symmetric, generally nonspherical whispering gallery resonators made of isotropic and anisotropic optical materials. It is based on analysis of the leading terms in the coupled equations for independent light-field components, as derived from Maxwell's equations, and true boundary conditions. Strong localization of the whispering gallery modes (WGMs) near the resonator rim, controlled by the azimuth modal number m, is the main prerequisite for our analysis. The theory gives high-precision expressions for the WGM frequencies and modal functions, including the evanescent effects. One of important applications of the theory is analysis of anticrossings of the WGM resonances in anisotropic resonators detected in experiments. Simple relations for the frequency avoidance gaps during the anticrossings are derived and compared with experimental data obtained in lithium-niobate-based WGM resonators. We show also that the vectorial effects substantially restrict the field of applicability of the scalar WGM models.
关键词： frequency avoidance gaps,whispering gallery resonators,anisotropic materials,vectorial perturbation theory,anticrossings
更新于2025-09-23 15:23:52
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Effect of anisotropic non-Kolmogorov turbulence on the evolution behavior of Gaussian Schell-model vortex beams
摘要： The effect of anisotropic non-Kolmogorov turbulence on the evolution behavior of average intensity and coherent vortices for Gaussian Schell-model (GSM) vortex beams is investigated. Based on the extended Huygens–Fresnel principle and power spectrum of the anisotropic non-Kolmogorov turbulence, the analytical expressions for the cross-spectral density and average intensity of GSM vortex beams propagating through anisotropic non-Kolmogorov turbulence are obtained. The evolution behavior of intensity and coherent vortices for GSM vortex beams in anisotropic non-Kolmogorov turbulence has been discussed in detail by numerical simulation. The results shown that the evolution behavior of coherent vortices and intensity profile depends on the effective anisotropic factor, generalized exponent factor and structure constant of anisotropic non-Kolmogorov turbulence, as well as the beam parameters, such as beam waist, wave length and correlation length.
关键词： Gaussian Schell-model vortex beams,Anisotropic non-Kolmogorov turbulence,Evolution behavior of coherent vortices
更新于2025-09-23 15:23:52
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[IEEE 2018 14th International Conference on Advanced Trends in Radioelecrtronics, Telecommunications and Computer Engineering (TCSET) - Lviv-Slavske, Ukraine (2018.2.20-2018.2.24)] 2018 14th International Conference on Advanced Trends in Radioelecrtronics, Telecommunications and Computer Engineering (TCSET) - Nanoengineering of anisotropic materials for creating the active optical cells with increased energy efficiency
摘要： In this paper the state-of-the-art for exploiting the unique physical and chemical properties of crystalline nanomaterials and their possible applications for creating optical cells with increased energy efficiency are discussed. Using a method of growing crystals from a solution the KDP and TGS nanocrystals were grown in the mesopores of the Al2O3 matrix where the direction of growth was discussed. To investigate the developed nanocomposites the X-ray analysis was used and it showed the predominant crystal orientation of the KDP and TGS in the direction [001] which coincides with the direction of the cylindrical pores. Thus, the possibility of growing of the KDP and TGS nanocrystals in the mesopores of the Al2O3 matrix was developed and provides the prospect of creating optical cells with increased energy efficiency.
关键词： X-ray analysis,anisotropic materials,crystalline nanocomposites,nanoporous matrices,Al2O3,nanofiller KDP and TGS
更新于2025-09-23 15:23:52
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UPML-ABC of dispersive materials for the unconditionally stable 2-D WLP-FDTD method
摘要： In this paper, uniaxial anisotropic perfectly matched layer (UPML) absorbing boundary condition (ABC) of dispersive materials is presented for 2-D finite-difference time-domain (FDTD) method with weighted Laguerre polynomials (WLP). Taking advantage of the auxiliary differential equation (ADE) technique, our proposed algorithm avoids not only the complicated formulations but also the convolution integral. Using ADE scheme, the relationship between field components and auxiliary differential variables is derived in Laguerre domain. Substituting auxiliary differential variables into UPML-ABC, the electric field E of order q can be expressed directly by magnetic field H in Laguerre domain. Inserting magnetic field H of order q into electric field, and using central difference scheme, the formulations of uniaxial anisotropic dispersive media PML are obtained. One numerical example of wave propagation in 2-D dispersive materials is simulated. Numerical results validate the efficiency of the presented method.
关键词： finite-difference time-domain (FDTD),weighted laguerre polynomials (WLP),uniaxial anisotropic dispersive materials,perfectly matched layer (PML),Auxiliary differential equation (ADE)
更新于2025-09-23 15:23:52