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2023

Record 409 of

Title:High Fidelity Image Reconstruction of Optical Sectioning Structured Illumination Microscopy

Author(s):Xie, Xianfeng(1,2); Qian, Jia(1); Li, Xing(1); Dang, Shipei(1); Bai, Chen(1); Min, Junwei(1); Dan, Dan(1,2); Yao, Baoli(1,2)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 52 Issue: 11 Article Number: 1110004 DOI: 10.3788/gzxb20235211.1110004 Published: November 2023
Abstract:In the research fields such as biomedicine and material science，researchers need to observe the Three-dimensional（3D）structure of samples. This promotes the development of 3D optical microscopic techniques，such as Laser Scanning Confocal Microscopy（LSCM），Light Sheet Fluorescence Microscopy （LSFM），Optical Sectioning Structured Illumination Microscopy（OS-SIM）. Among them，OS-SIM has the capability of extracting the in-focus target information from the out-of-focus background of the sample to enable 3D optical imaging. The quality of the optical sectioning image is directly related to the reconstruction algorithm. Although the traditional RMS algorithm is simple，the reconstructed image is often poor when the signal-to-noise ratio and the fringe contrast of the original image are not high，and the 3D reconstructed image is not ideal. To overcome the deficiencies of the RMS algorithm，a number of methods have been proposed，such as the Fast and Adaptive Bi-Dimensional Empirical Mode Decomposition-Hilbert Spiral Transform （FABMED-HS） method，Sequence Hilbert Transform （SHT） method，F(xiàn)ourier-OS-SIM method. All these methods provide different ideas for realizing 3D microscopic imaging. In this paper，we propose a new method，which can obtain high fidelity optical sectioning images. This method combines background removal and deconvolution processing，and finally obtains the optical sectioning image using standard deviation operation. Compared to the traditional RMS algorithm，the proposed method can effectively reduce the residual fringes and improve the visibility of minute details. Even in the low contrast of structured illumination where the RMS algorithm works abnormally，the STD algorithm can still perform well. Because the reconstruction formula of this method is similar to the standard deviation formula，the proposed method is named"STD （Standard Deviation） algorithm". Experimentally，a Digital Micro-mirror Device （DMD）based structured illumination microscope is built. In this microscope，a Laser Diode Illuminator（LDI）is used as light source that provides illumination of seven wavelength channels. The DMD has a resolution of 1 920×1 080 pixels，with a pixel size of 7.56 μm×7.56 μm. The SCOMS camera has a resolution of 2 048× 2 048 pixels，with a pixel size of 6.5 μm×6.5 μm. Firstly，we compare the reconstructed images of STD algorithm and RMS algorithm using mouse kidney cells and Bovine Pulmonary Artery Endothelial（BPAE）cells as samples. The experimental results demonstrate that RMS algorithm has better optical sectioning capability. The STD algorithm is also applied to previously collected data with a mite as the sample. The experimental results again suggest the robustness of the STD algorithm. And then，we find that changing the illumination wavelength has little effect on the imaging position，which makes it possible to optical sectioning at multiple wavelengths. We obtain dual-wavelength fluorescence images by using 470 nm and 555 nm to excite the mouse kidney cells samples. Finally，3D imaging experiments is performed with pollen samples. The field-of-view of the image is 163.84 μm×163.84 μm. We took 125 layers of images，each thickness is 200 nm. Using the STD algorithm，we get sharp 3D images. All the above experimental results demonstrate that the STD method can obtain better optical sectioning 3D images compared to the RMS method. ? 2023 Chinese Optical Society. All rights reserved.
Accession Number: 20235015214459
Record 410 of

Title:Terahertz Polarization Multiplexing Computer-generated Holography Based on All-dielectric Metasurface

Author(s):Zhang, Yuming(1,2); Fan, Wenhui(1,2); Wu, Qi(1,2); Qin, Chong(1,2)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 52 Issue: 8 Article Number: 0809001 DOI: 10.3788/gzxb20235208.0809001 Published: August 2023
Abstract:Compared with using the light interference of two actual beams to obtain holograms，computed holography has the advantages of low noise， simple operation， high repeatability， and holographic reproduction of virtual objects. Meanwhile，computer-generated holography technology is commonly used to reconstruct arbitrary images and is widely used in virtual reality，advertising and anti-counterfeiting systems. Terahertz wave refers to the electromagnetic wave between 0.1 THz~10 THz， between millimeter wave and far infrared wave. The unique spectral position of terahertz waves gives it the advantages of low photon energy， rich spectral information， strong penetration ability， and large bandwidth. Based on the above characteristics， terahertz holographic technology is widely used in biomedical imaging，safety screening，non-destructive testing，and evaluation fields. However，limited by the inherent refractive index of natural materials，traditional propagation and reflective terahertz functional devices are usually composed of High-density Polyethylene（HDPE），Polytetrafluoroethylene（PTFE），Polymethylpentene（TPX），quartz and sapphire，which inevitably leads to their large size，heavy weight and low efficiency，which hinders the development of miniaturization and integration of terahertz systems. Metasurface refers to a two-dimensional array of sub-wavelength artificial unit structures arranged on a plane. It can flexibly adjust the wavefront amplitude，phase，polarization，and orbital angular momentum through ease of integration and manufacturing，with the potential to control electromagnetic waves flexibly. It retains the advantages of electromagnetic regulation of three-dimensional metamaterials， and its preparation difficulty and propagation loss are significantly reduced due to its planar structure characteristics. The design of a suitable metasurface element structure can afford the capability to modulate the optical field flexibly，thereby enabling the realization of diverse functionalities，such as beam focusing，beam diffraction，generation of specialized beams，beam shaping，and holographic image reconstruction. Based on the above research background，this paper uses the GS algorithm to obtain the optimal solution distribution of the target object's phase. Then it uses the all-silicon rectangular column as the basic unit structure to arrange metasurface-regulated terahertz waves to achieve holographic imaging. This research proposes a new type of meta-atom structure，the all-silicon rectangular column，as the fundamental building block for the terahertz metasurface. This design overcomes the drawbacks of traditional metal-based metasurfaces， such as high ohmic losses and low polarization conversion efficiency， by implementing Mie-type electrical resonance and magnetic resonance or an effective waveguide effect. These phenomena result in the modulation of wavefronts at terahertz frequencies. Different phase regulation methods are used to design metasurfaces to achieve holographic imaging with different functions. Metasurfaces based on geometric phase control can realize holographic imaging and verify that the obtained image has a specific broadband. On this basis， the rational design of the metasurface element structure realizes a circular-bias multiplexing function based on the simultaneous regulation of the geometric phase and propagation phase. The specific function realized is to obtain holographic images of the letter E when right-handed circularly polarized light is incident light. When left-handed circular polarized light is incident，a hologram of the letter F is obtained. Compared with the holographic diffraction efficiency obtained by using metasurfaces made of metal，the diffraction efficiency of holograms can be effectively improved by using the all-silicon column structure. To a certain extent，this design solves the shortcomings of considerable size，heavy weight and low efficiency of traditional functional devices in the terahertz band and promotes the development of integrated and multifunctional terahertz technology in the terahertz band. It shows excellent potential for holographic imaging and wavefront regulation applications. The polarization multiplexed holographic imaging proposed in this paper can store multiple pieces of information in one carrier，set the incident light in different polarization states to obtain different information，and present different holograms. The implementation of this approach utilizing the metasurface can result in the enhancement of multi-channel holographic imaging， thereby significantly increasing the utilization efficiency of the metasurface technology. This not only has significant potential in terms of large-scale information storage but also has potential applications in polarized optics and holographic data encryption. ? 2023 Chinese Optical Society. All rights reserved.
Accession Number: 20233714721534
Record 411 of

Title:A Comprehensive Equivalent Circuit Model of Silicon-Based Segmented Microring Modulators for Electronic and Photonic Integrated Circuit Codesign

Author(s):Bao, Shenlei(1,2); Xue, Jintao(1,2); Wu, Jinyi(1,2); Wang, Binhao(1,2)
Source: 2023 Asia Communications and Photonics Conference/2023 International Photonics and Optoelectronics Meetings, ACP/POEM 2023 Volume: null Issue: null Article Number: null DOI: 10.1109/ACP/POEM59049.2023.10369115 Published: 2023
Abstract:We present an equivalent circuit model for two-segment Si microring modulators (MRMs). The model consists of three blocks: electrical parasitics, electro-optic dynamics, and self-heating effects. Model parameters are derived through curve fitting based on Si MRM characterization. An excellent agreement between simulated and measured eye diagrams at a data rate of 106Gb/s was achieved. This equivalent circuit model can be effectively employed for driver design optimization and MRM wavelength stabilization circuitry improvement. ? 2023 IEEE.
Accession Number: 20240515453288
Record 412 of

Title:Broadband Mid-Infrared Frequency Comb Generation in a Large-Cross-Section Silicon Microresonator

Author(s):Wang, Wenrui(1,2); Ming, Xianshun(1); Shi, Lei(1,2); Ma, Kai(1); Ren, Dezheng(1,2); Sun, Qibing(1); Wang, Leiran(1,2); Zhang, Wenfu(1,2)
Source: IEEE Photonics Journal Volume: 15 Issue: 3 Article Number: 6601406 DOI: 10.1109/JPHOT.2023.3273731 Published: June 1, 2023
Abstract:As a novel portable and robust broadband coherent light source, mid-infrared (MIR) Kerr microresonator-based frequency combs (microcombs) have prospective applications in the precision spectroscopy of molecules and biochemical sensing. The mature integrated silicon photonics platform is well suited for the MIR microcombs study because silicon has both large linear and nonlinear refractive index, but the transparency window of the platform is limited by the cladding material. Here, we numerically demonstrate the generation of a broadband MIR comb in a silicon microring resonator, harnessing the large-cross-section air-cladding waveguide to alleviate the absorption loss. The effects of higher order nonlinearities are also investigated, which show that the effect of five-photon absorption around the pump wavelength (4.78 μm) is negligible while an octave-spanning (3.5-8 μm) Raman-Kerr comb line can be obtained with the assistance of Raman effect and a quite pure Kerr frequency soliton comb can also be achieved at large detuning. The proposed structure can be compatible with the CMOS technology, thus can be a very promising solution to the MIR integrated photonics. ? 2009-2012 IEEE.
Accession Number: 20232114131598
Record 413 of

Title:Design and Preparation of Mid-infrared 7×1 Sulfide Fiber Combiner

Author(s):He, Chunjiang(1,2); Xiao, Xusheng(1); Xu, Yantao(1); Xiao, Yang(1,2); Zhang, Hao(1,2); Guo, Haitao(1)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 52 Issue: 11 Article Number: 1106003 DOI: 10.3788/gzxb20235211.1106003 Published: November 2023
Abstract:As a core component of a fiber laser system，the fiber combiner not only directly determines the pump and output power of fiber lasers，but also serves as an important guarantee for the safe operation of the all-fiber laser system in a high-power environment. At the same time，the fiber combiner is simple and stable in structure，and not easy to be interfered with by the outside environment. It can realize the expansion of power and spectrum without a lot of optical components and free space optical devices. The fiber combiner that can transmit lights in the mid-infrared band has attracted much attention because of its wide application in national defense，military，scientific research and business. In addition，due to its significant design and preparation difficulties， only a few institutions currently master the relevant technology. As a very important part of mid-infrared photonic devices，it has become a research hotspot in this field all over the world. In this paper，in theory，the optical field distribution of multimode fiber combiner is analyzed and the power loss of several main modes in the fiber core is calculated. The mechanism of loss in the tapering process of fiber combiner is elucidated. The basic criteria of adiabatic tapering and brightness conservation are analyzed in detail，which lays a foundation for the design of high transmission efficiency and good beam quality combiners. Experimentally，starting with the preparation process and key technologies of mid-infrared sulfide fiber combiner device，the 7×1 sulfide fiber combiner device with high performance has been successfully developed after solving the key problems of the ordered arrangement，melting tapering，end cutting，homogeneity fusion and end angle polishing. The key performance indexes are tested and analyzed. In terms of testing and characterization，the transmission efficiency，beam quality，structural stability and power damage threshold of the 7×1 mid-infrared sulfide fiber combiner are tested by using mid-infrared light source，detector and beam quality analyzer. The average transmission efficiency of nearly 80%(@4.778 μm)is obtained for different ports of the 7×1 sulfide fiber combiners. When the diameter of the output fiber core is about 350 μm，the best M2x/y value of the 7×1 sulfide fiber combiner is 19.63/22.48. The tensile tension at the fusion point is more than 300 g，which is better than similar structures. When the input laser power (@1.976 μm) exceeds 10 W，the maximum output power of the 7×1 sulfide fiber combiner can reach 4.32 W. This paper provides some ideas for the processing of mid-infrared sulfide fiber and the fabrication of fiber combiner devices. On the one hand，mid-infrared fiber as the main body of mid-infrared fiber combiner，its performance largely determines the final performance of the fiber combiner. In recent years，mid-infrared single-mode fiber，multi-mode fiber and mid-infrared doped fiber with low loss have been prepared. However， compared with commercial quartz fiber， the preparation technology of high performance mid-infrared fiber is still immature，which is the main reason limiting the development of mid-infrared fiber combiners and other mid-infrared fiber devices. On the other hand，how to optimize the soft glass fiber processing platform and eliminate the influence of preparation process on device performance as much as possible is also a problem to be solved in the future. ? 2023 Chinese Optical Society. All rights reserved.
Accession Number: 20235015214296
Record 414 of

Title:30 W all-fiber supercontinuum generation via graded-index multimode fiber pumped by picoseconds laser pulse

Author(s):Zhang, Ting(1,2); Hu, Xiaohong(1); Pan, Ran(1,2); Wang, Zhenguang(1); Zhang, Wei(1); Guo, Yashuai(1,2); Feng, Ye(1); Wang, Yishan(1); Zhao, Wei(1)
Source: Optics and Laser Technology Volume: 159 Issue: null Article Number: 108943 DOI: 10.1016/j.optlastec.2022.108943 Published: April 2023
Abstract:We demonstrated an over 30 W all-fiber supercontinuum source based on a four-mode graded-index multimode fiber (GIMF) pumped by around 5 picoseconds laser pulse. Following the evolution of the supercontinuum, it is reasonable to conclude that the discrete spectral peaks in the range 350–700 nm were generated owing to the geometric parametric instability effect and quasi-phase matched harmonic generation, whereas the radiation of dispersive waves, stimulated Raman scattering, and relative effects of optical soliton caused spectral broadening ranging from 700 nm to 1750 nm (and even to 2400 nm). Furthermore, the properties of the supercontinua generated in the four-mode GIMF and the 50/125 standard GIMF were experimentally compared. This comparison implied that the wavelengths radiated by the geometric parametric instability differed owing to different dispersion values. And the supercontinuum generated by the four-mode GIMF had a flatter spectral profile and a wider wavelength range. ? 2022
Accession Number: 20230213352971
Record 415 of

Title:Research Status and Prospect of Low Thermal Resistance Liquid-cooled Heatsink Applied in Laser Diode

Author(s):Chen, Lang(1); Liu, Jiachen(1,2); Zhang, Jiachen(1); Wang, Zhenfu(1); Wang, Dan(1); Li, Te(1)
Source: Cailiao Daobao/Materials Reports Volume: 37 Issue: 10 Article Number: 21120232 DOI: 10.11896/cldb.21120232 Published: May 25, 2023
Abstract:In recent decades, the output power of laser diode has been continuously increasing, leading to the restricted problem of thermal loads. The thermal load causes a temperature increment in the active region of the LD chip, which further impacts the chip temperature distribution and leads to a gradual deterioration of the LD bar performance. For a defined package configuration, the thermal resistance of the heatsink becomes a decisive factor in controlling the temperature rise. Therefore, it is important to reduce the thermal resistance of the heatsink in order to improve the output power capability and beam properties of semiconductor lasers. From three aspects:liquid-cooled heatsink materials, liquid-cooled heatsink structures and liquid-cooled refrigerant properties, this paper reviews the evolution of thermal resistance of liquid-cooled heatsinks in the last three decades. We also summarize the factors influencing thermal resistance during the development of liquid-cooled heatsinks, and further discuss the development direction and application prospects of heatsink thermal resistance reduced. ? 2023 Cailiao Daobaoshe/ Materials Review. All rights reserved.
Accession Number: 20232514277801
Record 416 of

Title:High-quality Subwavelength Grating Structures Fabrication on Fused Silica Surfaces by Femtosecond Laser

Author(s):Liu, Yang(1,2,3); Zhu, Xiangping(1,2,3); Jin, Chuan(1,2,3); Zhang, Xiaomo(1,2,3); Zhao, Wei(1,2,3)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 52 Issue: 7 Article Number: 0752307 DOI: 10.3788/gzxb20235207.0752307 Published: July 2023
Abstract:The"moth eye"micro-nano structure has recently attracted much attentions due to its high potential value in scientific，biomedical，and industrial applications. For example，by manufacturing specific micro-nanostructures on the surface of an optical device，the incident light would be reflected multiple times on its surface，which lets the surface achieve the co-called"light trap effect"，reducing the transmission loss caused by Fresnel reflection at the interface. Laser Induced Periodic Surface Structures （LIPSS） provide a robust， flexible， non-contact， simple， and low-cost potential method for the fabrication of large-scale surface micro-nanostructures. As the most frequently used material on optical devices，it is of great significance to study the fabrication of optical micro-nanostructures on fused silica surfaces. In this paper，by using Ti：sapphire femtosecond laser processing system，the general laws of femtosecond laser induced LIPSS morphology on fused silica samples have been studied. Through designed experiments，the effects of different laser fluence and repetition frequency，pulse number，spot size，and pulse spatial interval on the morphology of LIPSS on fused silica surface were studied. We also focus on how to obtain the high-quality LIPSS，which can have a great impact on the final performance of the device. Different fluences were first set in the experiments. It was found that at a laser fluence of 5 J/cm2，irregularly arranged nanospikes were densely distributed in the crater，and at 7 J/cm2，ripple-like structures appeared in the center of the crater. After that，as the laser fluence increased，the periodicity increased，accompanied by an increase in proportion. A laser surface plasma interference model is used to explain the relationship between periodicity and laser fluence， which is in good agreement with the observed phenomena. In order to investigate the effect of laser spot size（or the influence aera size of laser spot）on the morphology of LIPSS，diminished laser spot sizes were set to observe the changes. To further reduce the size of laser spot，the concept of threshold effect was adapted. The results show that by the reduction of laser spot size，the LIPSS stripe becomes more regular. A grating-like LIPSS with good quality can be obtained under the 1 μm diameter of laser spot when the laser fluence is set around 3.7 J/cm2. The effects of pulse number and laser repetition rate on LIPSS were also studied in this work. The results showed that only some defects could be observed on the surface when the pulse number was set to 1. As the pulse number increased，the ripple-like structures gradually appeared，but were irregular. When the pulse number was set to be 10，relatively intact fringes showed up. It is found that the periodicity of the fringes showed a decreasing trend with the increase of the pulse number. It is also found that changing the laser repetition rate alone has no significant impact on the morphology of LIPSS. Considering that laser fabrication is a line scanning process，there is a certain spatial distance between pulses. Therefore，we studied the effect of pulse spatial interval on the morphology of LIPSS. The results showed that when the spatial interval of pulses is similar to the periodicity that the LIPSS structure under current parameter conditions，high-quality，regular，long-range arrayed grating structures can be obtained. Specifically，we adopt the following parameters，1 μm diameter of laser spot，a scanning speed of 20 μm/s，repetition rate 100 Hz，and laser fluence 4.2 J/cm2，and a highly regular long range aligned nanograting structure was fabricated，with a period of 200~300 nm and the depth of about 300 nm. The results found in this work may be conducive to promoting the development of surface micro-nano optical structures on fused silica. ? 2023 Chinese Optical Society. All rights reserved.
Accession Number: 20233714721494
Record 417 of

Title:Orbiting and Non-axial Spinning Motion of Particle in Tightly Focused Circularly Polarized Vortex Beam

Author(s):Cai, Yanan(1); Yan, Shaohui(2); Zhang, Yanan(2); Liu, Mulong(1); Zhang, Rui(1); Ren, Wenyi(1); Yao, Baoli(2)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 52 Issue: 11 Article Number: 1126001 DOI: 10.3788/gzxb20235211.1126001 Published: November 2023
Abstract:Optical angular momentum，which can realize the non-destructive and non-contact rotation control of micro-particle is of great significance to study the rotational mechanical properties of biological macromolecules，to understand the biocatalysis effect，and to reveal the mechanism of biological energy conversion. The angular momentum is comprised of spin angular momentum and orbital angular momentum. Spin angular momentum is associated with the polarization of the optical field and can cause particles to spin. Orbital angular momentum comes from the helical wave-front structure associated with the central phase singularity of the optical field and can cause particles to make circular trajectories. Normally，the orientation of the angular momentum is parallel to the optical axis（the direction in which the beam propagates），which is called the axial angular momentum. Such optical fields can induce particles to rotate around the optical axis when interacting with particles. In recent years，transverse spin angular momentum has been found in structured light fields such as evanescent，interference，and focusing field. Different from the traditional axial angular momentum，transverse spin angular momentum can drive the particle to rotate in the direction perpendicular to the optical axis，introducing a new degree of freedom for optically induced rotation technology，which is therefore expected to improve the flexibility of optically induced rotation. At present，non-axial rotation control of particles in the evanescent and interference fields have been implemented. However，the effect of transverse spin angular momentum in focusing fields still needs more attention and much deeper investigation. This paper will show some theoretical and experimental results on such an effect. A circularly polarized beam is believed to carry axial spin angular momentum. As a result，it is hard to realize transverse spinning of particles in such a beam. Nevertheless，under tight focusing，the focusing fields of such beam may carry transverse spin angular momentum. Optical vortex beams carry orbital angular momentum，and can induce orbital rotation of particles. In tightly focused vortex beams，there also exists induced spinning motion of some particles. Optical vortex beams with circular polarization carry both spin angular momentum and orbital angular momentum，and can realize non-axial spinning and orbiting motion of particles. Here，the dynamics of optically induced motion of circularly polarized vortex beams are studied. By use of T-matrix method，the optical forces and torques exerted on a particle are evaluated，and the influence of the orientation of spin angular momentum and orbital angular momentum on the non-axial spinning motion of particle is analyzed. The numerical results show that in the tightly focusing fields of circularly polarized vortex beams，the particle is trapped near the intensity maxima for orbital motion. When the direction of orbital angular momentum is the same as that of spin angular momentum，the trapped particle will experience a considerable transverse spin torque in addition to the longitudinal spin torque and the orbital torque，thus will induce a non-axial spinning of particle. When the direction of orbital angular momentum is opposite to that of spin angular momentum，the transverse spin torque will be too small to drive the non-axial spinning of particle. Finally，the holographic optical tweezers system has been applied to experimentally investigate the complex motion forms of the light-induced rotation in the focusing fields of circularly polarized vortex beams. The experimental results show that the direction of orbiting motion of trapped microparticle is determined by the sign of the topological charge of the vortex beam. And when the orbital angular momentum and the spin angular momentum in the circularly polarized beams have the same direction，the trapped microparticle orbits around the optical axis while，but also experiences a non-axial spinning motion. The experimental results agreed well with the theoretical results. ? 2023 Chinese Optical Society. All rights reserved.
Accession Number: 20235015214405
Record 418 of

Title:Low-cost Terahertz Polarizers Manufacture in Virtue of PCB Production Process

Author(s):Mu, Qiyuan(1,2); Wang, Shijie(2); Ma, Tian(3); Kong, Depeng(2)
Source: Proceedings - 2023 Cross Strait Radio Science and Wireless Technology Conference, CSRSWTC 2023 Volume: null Issue: null Article Number: null DOI: 10.1109/CSRSWTC60855.2023.10426897 Published: 2023
Abstract:This paper presents analysis of structural parameters impacting the polarization performance of a linear gate polarizer, then introduces the preparation process with a simple and cost-effectiveness method. This process offers several key advantages, including mature technology, a short preparation timeframe, and the crucial capability for mass production. The polarizer produced by this method has a thin and strong base, is structurally stable and can be easily mounted on a rotatable bracket for immediate use. Performance assessment is conducted using a terahertz time-domain spectrometer, high transmittance and extinction ratio are obtained, and the results demonstrate a strong correlation between the numerical analysis and experimental outcomes. ? 2023 IEEE.
Accession Number: 20241015675839
Record 419 of

Title:Third-Order Nonlinear Effect and Polarization-Dependent Modulation Using Spherical-Like MoS2 Nanoparticles

Author(s):Li, Tianlun(1); Hao, Rui(2); Hou, Yaping(1); Gao, Duorui(3); Xu, Yunfan(1); Zhang, Yanpeng(1); Fang, Jixiang(2); Zhang, Lei(1)
Source: Annalen der Physik Volume: 535 Issue: 1 Article Number: 2200378 DOI: 10.1002/andp.202200378 Published: January 2023
Abstract:A type of MoS2 nanoparticle with a spherical-like shape is chemically synthesized with favorable third-order and suppressed second-order nonlinear optical response, which results from the isotropy induced by the geometrical uniformity of nanoparticles and an artificial symmetry center. It is found that the linewidth of third harmonic signal is broadened due to the self-phase modulation effect, another third-order nonlinearity. Moreover, the intensity of harmonic signal can be conveniently adjusted by controlling the polarization state of applied optical field. The artificially designed material morphology may provide a reference for designing all-optical modulation devices. ? 2022 Wiley-VCH GmbH.
Accession Number: 20224513088218
Record 420 of

Title:Numerical simulation of the argon dielectric barrier discharge driven by dual frequency at atmospheric pressure

Author(s):Qi, Bing(1,2,3,4); Tian, Xiao(5); Zhang, Tao(6); Wang, Jing(7); Wang, Yishan(1,3); Si, Jinhai(2); Tang, Jie(1,3)
Source: AIP Advances Volume: 13 Issue: 6 Article Number: 065327 DOI: 10.1063/5.0152839 Published: June 1, 2023
Abstract:Argon dielectric barrier discharge driven by the dual frequency at atmospheric pressure has been investigated by a 1D fluid model. Temporal evolutions of voltage and charge density on dielectric surface, fluxes of electrons and ions on the surface, the spatiotemporal distribution of electron generation rate, and the spatial distribution of electron density are studied with various low-frequency (LF) voltages. Minimum sustained discharge amplitude of high frequency (HF) voltage and spatiotemporal mean electron density over one LF period varying with sheath voltage (α → γ) are also discussed. Results show that in α mode, the electron flux on the dielectric surface decreases significantly when the LF voltage amplitude is lower while the ion flux is less affected. The positive charge density on the surface increases, causing the surface voltage waveform to shift upward. When the LF voltage amplitude is 40 V and that of HF voltage is 87 V, the positive and negative values of voltage amplitude of dielectric surface are 182 and 32 V. As the LF voltage amplitude increases further, the sheath formation time is significantly delayed and the discharge terminates, and the rate of electron generation decreases significantly. The discharge is extinguished when the amplitude of LF voltage is 68 V while it regains when the amplitude reaches up to 750 V. In γ mode, when the amplitude of HF voltage reaches or exceeds its minimum sustained discharge value, the generation and distribution of electrons are almost unaffected by the amplitude of LF voltage. ? 2023 Author(s).
Accession Number: 20232614309901

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