2024

• Record 49 of
  
  Title:A systematic study on linear thermal expansion coefficient of metals based on interferometric measurement with Fresnel bimirror
  
  Author(s):Lu, Sifan(1); Zhao, Wenyu(1); Lin, Jia(1); Zhao, Xiaorui(1); Xu, Ruoyu(1); Bai, Jin(1); Sun, Chunyan(1,2,3)
  Source:Microwave and Optical Technology Letters
  Volume: 66  Issue: 5  DOI: 10.1002/mop.34178  Published: May 2024  
  Abstract:Linear thermal expansion coefficient, which is vital for measuring the thermal expansion characteristics of metals, has been attracting considerable attention globally. Herein, a novel design based on Fresnel bimirror has been developed. In this design, when the upper end of the object to be measured comes in contact with a tilted double-sided mirror, the temperature rises and intersection angle of the Fresnel bimirror decreases. Meanwhile, interference fringe spacing becomes narrower, while the number of fringes increases. An imaging system based on a digital microscope and smartphone is also incorporated in this design, which records the changes in the interference fringes. Then, using a self-programmed software, the linear thermal expansion coefficients of Cu, Fe, and Al samples are determined at elevated temperatures as 17.85 ± 0.23 × 10−6/°C ((Formula presented.)), 11.8 ± 0.09 × 10−6/°C ((Formula presented.)), and 23.34 ±0.16 × 10−6/°C ((Formula presented.)), respectively, with a relative error of less than 1.6%. A cooling process is also designed, and the average value of the linear thermal expansion coefficient of metal samples during heating and cooling conditions is determined. The measurement results obtained via the finite-method simulation demonstrate the feasibility and reliability of the system. Overall, this study provides a new idea for measuring the linear thermal expansion coefficient of metals. © 2024 Wiley Periodicals LLC.
  Accession Number: 20242016085779
• Record 50 of
  
  Title:Computational imaging-based single-lens imaging systems and performance evaluation
  
  Author(s):Wei, Shijie(1); Cheng, Huachao(1,2); Xue, Ben(1,2); Yang, Xihang(1); Ma, Yinpeng(1,3); Wang, Yue(1); Xi, Teli(1,2); Shao, Xiaopeng(4)
  Source:Optics Express
  Volume: 32  Issue: 15  DOI: 10.1364/OE.527950  Published: July 15, 2024  
  Abstract:The minimalist optical system has a simple structure, small size, and lightweight, but the low optical complexity will produce optical aberration. Addressing the significant aberration degradation in minimalist systems, we propose a high-quality computational optical framework. This framework integrates a global point spread function (PSF) change imaging model with a transformer-based U-Net deep learning algorithm to achieve high-quality imaging in minimalist systems. Additionally, we introduce an imaging performance evaluation method based on the modulation transfer degree of resolution (MTR). We addressed severe chromatic and spherical aberrations in single-lens systems, a typical example of minimalist optical systems, by simulating the degradation process and reconstructing the imaging effects. This approach demonstrated significant improvements, thus validating the feasibility of our method. Specifically, our technique calculated the MTR values in real images captured with the GCL010109 single lens at 0.8085, and with the GCL010110 single lens at 0.8055. Our method enhanced the imaging performance of minimalist systems by 4 times, upgrading minimalist system capabilities from poor to good lens grade. This work can provide reference for wavefront coding, matelens, diffraction optical systems, and other computational imaging work. It can also promote the application of miniaturization of medical, aerospace, and head-mounted optical systems. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20243016735186
• Record 51 of
  
  Title:A triangular—trapezoidal dual-channel shaping algorithm for resistive anode readout systems and its FPGA implementation
  
  Author(s):Zhang, Wen-Wen(1); Song, Yu-Chao(1); Zheng, Jin-Kun(2,3); Yang, Yang(2,4); Bai, Yong-Lin(2,3); La, An-Peng(1); Duan, Jin-Yao(2,3); Zhao, Hua(5); Zhang, Yan-Xin(5); Wang, Fang(5)
  Source:Review of Scientific Instruments
  Volume: 95  Issue: 8  DOI: 10.1063/5.0202553  Published: August 1, 2024  
  Abstract:This paper introduces a novel digital triangular-trapezoidal double-channel shaping algorithm to enhance the counting rate of resistive anode detectors. The algorithm is based on the trapezoidal shaping algorithm and improves it. At the extreme counting rate, the trapezoidal shaping algorithm cannot alleviate the pulse pileup, so the counting rate cannot meet the requirements of a high performance detector. The triangular-trapezoidal double-channel shaping algorithm is introduced in the resistance anode detector, which can replace the trapezoidal shaping filtering algorithm to process the output signal of the resistance anode detector and obtain the single photon position information. This improvement improves the counting rate of the resistor anode detector and reduces the resolution degradation caused by pulse pileup. The algorithm is simulated by System Generator software and implemented on FPGA (field programmable gate array). The triangular-trapezoidal double-channel shaping algorithm presented in this paper plays an important role in reducing electronic noise and pulse pileup. The algorithm is subjected to simulation testing, and it can recognize signals with a minimum pulse interval of 1 µs and counting rate up to 1000 kcps. © 2024 Author(s).
  Accession Number: 20243516927816
• Record 52 of
  
  Title:Highly sensitive Ga2O3 MSM solar-blind UV photodetector with impact ionization gain
  
  Author(s):Wan, Qiyi(1,2); Zhang, Anzhen(1,2); Cao, Weiwei(1,3); Bai, Yonglin(1,2); Wang, Bo(1,2); Cheng, Hang(1,2); Wang, Gang(1,2)
  Source:Optics Express
  Volume: 32  Issue: 18  DOI: 10.1364/OE.531784  Published: August 26, 2024  
  Abstract:In this study, a (400) crystal-oriented β-Ga2O3 thin film with a thickness of approximately 400 nm was grown on a c-plane sapphire substrate using atomic layer deposition. Schottky contact-type metal-semiconductor-metal solar-blind ultraviolet detectors with an Au/Ni/Ga2O3/Ni/Au structure were fabricated on the epitaxial thin films. The Schottky barrier height is about 1.1 eV. The device exhibited a high responsivity of up to 800 A/W, and a detectivity of 6 × 1014 Jones while maintaining a relatively fast response speed with a rise time of 4 ms and a fall time of 12 ms. The photo-to-dark current ratio was greater than 103, and the external quantum efficiency exceeded 103, indicating a significant gain in the device. Through the analysis of TCAD simulation and experimental results, it is determined that the impact ionization at the edge of the MSM electrode and channel contact is the main source of gain. Barrier tunneling effects and the photoconductive effect due to different carrier mobilities were not the primary reasons for the gain. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20243616997102
• Record 53 of
  
  Title:Spatiotemporal vectorial structured light that dynamically varies on higher-order Poincaré sphere
  
  Author(s):Liang, Yize(1,2,3,4); Xi, Teli(1,2); Cao, Shuai(1,2); Liu, Lixian(1,2); Liu, Fei(1,2); Wan, Zhenyu(3,4); Wang, Jian(3,4); Shao, Xiaopeng(5)
  Source:Optics Express
  Volume: 32  Issue: 16  DOI: 10.1364/OE.525629  Published: July 29, 2024  
  Abstract:Higher-order structured light beams, including optical vortex (OV) beams and vector beams, which can be geometrically represented as points on higher-order Poincaré spheres (HOPSs), have been widely exploited in applications such as optical trapping, optical communications, optical metrology, quantum optics, to name a few. To date, traditional approaches to producing such higher-order structured light beams deal with controllable generation of different static points on HOPS. In this paper, we propose and demonstrate the generation of spatiotemporal structured light beams that dynamically vary on HOPS. By superposing OV beams with different frequencies, spatiotemporal vectorial structured light beams that dynamically vary along latitude lines, meridians, and other trajectories on the first order Poincaré sphere are generated in simulation. Our work may give new insight into arbitrarily and ultrafast tailoring higher-order structured light beams. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20243216825749
• Record 54 of
  
  Title:Tunable band-stop fiber filter based on laser-induced graphene metamaterial in THz frequency
  
  Author(s):Tian, Ziping(1); Luo, Zhenyang(1); Lv, Xianpeng(1); Xie, Manyan(1); Peng, Gangding(2); Kong, Depeng(3); Lu, Huihui(4); Guan, Heyuan(4)
  Source:Optics Express
  Volume: 32  Issue: 14  DOI: 10.1364/OE.527472  Published: July 1, 2024  
  Abstract:As an important device in the application of terahertz (THz) technology, a THz filter has broad application prospects in the fields of THz communication, imaging, and sensing. In this paper, a THz filter based on grating structure laser-induced graphene (LIG)/ side polishing terahertz fiber composite structure is proposed. In the experiment, we achieved the maximum Q factor of 23.83 at the central resonant frequency of 0.715 THz. By modifying the grating structure, a tunable operational span of 269 GHz was achieved, along with a tunable range of 21 GHz through laser stimulation. In testing, we found that LIG materials prepared with circular filling are more sensitive to relatively high-power pump lasers, while LIG samples prepared with line filling exhibit better linear response to laser power. Furthermore, the compact and highly integrated nature of the device suggests its broad potential utility in the realm of THz frequency selection. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20242916703870
• Record 55 of
  
  Title:Environmentally stable Mn-doped CsPbX3@CsPb2X5 core-shell materials with efficient energy transfer
  
  Author(s):Zhang, Chen(1); Xu, Luxia(2); Wang, Minqiang(1); Da, Zheyuan(1); Shi, Jindou(1); Wang, Junnan(1); Yao, Qing(1); Tian, Jinshou(2); Gaponenko, Nikolai V.(3); Xu, Youlong(1)
  Source:Journal of Materials Chemistry C
  Volume: 12  Issue: 35  DOI: 10.1039/d4tc01135j  Published: July 27, 2024  
  Abstract:Mn(ii)-doped cesium lead halide perovskite (CsPbX3 (X = Cl, Br, I)) quantum dots (QDs) have attracted a lot of attention from researchers attributed to their bright orange light emission. However, defects such as inefficient energy transfer and instability have hindered the commercial application of the material. Here, we propose a convenient core-shell coating strategy to epitaxially grow a CsPb2X5 shell on Mn-doped CsPbX3 surfaces by controlling the reaction time and precursor ratio. Meanwhile, density-functional theory (DFT) calculations indicate that a typical type-I heterojunction is formed between the CsPb(Cl/Br)3 cores and the CsPb2(Cl/Br)5 shell, which improves the energy transfer efficiency from an exciton to Mn2+. The obtained Mn-doped CsPb(Cl/Br)3@CsPb2(Cl/Br)5 core-shell materials exhibit enhanced optical properties and excellent water/thermal stability. Subsequently, the white light-emitting diode prepared from the composites shows a high luminescence efficiency of 127.21 lm W−1, and the PL intensity is still maintained above 95% after 24 h of continuous operation. © 2024 The Royal Society of Chemistry.
  Accession Number: 20243316882218
• Record 56 of
  
  Title:Application of Temperature In-situ Monitoring Based Microreactor in HNS Microfluidic Preparation Process
  
  Author(s):Huang, Jian(1,2); Shi, Yu-Kun(1,2); He, Xin(1,2); Zhang, Song(3); Han, Rui-Shan(3); Zhou, Ji-Ming(1,2); Zhang, Fang(3); Wu, Meng-Xi(1,2); Liu, Jun-Shan(1,2)
  Source:Huozhayao Xuebao/Chinese Journal of Explosives and Propellants
  Volume: 47  Issue: 6  DOI: 10.14077/j.issn.1007-7812.202403011  Published: June 2024  
  Abstract:In order to resolve the lack of temperature in-situ monitoring means during the microfluidic preparation of energy-containing materials, a microreactor system with an integrated thin-film temperature sensor is proposed. The microreactor consists of a glass substrate containing the thin-film temperature sensor bonded to a silicon substrate containing the microfluidic channel. Three temperature sensors are placed upstream, midstream, and downstream of the microfluidic channel to achieve high spatial resolution temperature measurement during the microreaction process. Based on this microreactor, a continuous microfluidic preparation system for hexanitrostilbene (HNS) is constructed, and the temperature changes during the micro- and nanosizing and sphericalisation of HNS are monitored in real time. The results show that the microreactor has the advantages of high precision, corrosion resistance and observability. HNS micro- and nanosizing is an exothermic reaction with a maximum fluid temperature rise of 6.4 C. Due to the gradual precipitation of HNS, the solid content in the fluid increases, the flow rate slows down, and the distribution of the fluid temperature changes. The mixing of two-phase fluids during the HNS spheronisation process is an exothermic process, with a maximum temperature rise of 2.3 °C. The temperature at the midstream of the microfluidic channel is significantly higher than that at the upstream and downstream, and it is deduced that when the droplets flow to the midstream, the HNS microspheres have already been prepared. © 2024 China Ordnance Industry Corporation. All rights reserved.
  Accession Number: 20243116775758
• Record 57 of
  
  Title:Mathieu ray-wave structured light with self-healing elliptical accelerating vortices
  
  Author(s):Wei, Wenjun(1); Tang, Miaomiao(1); Zhang, Hao(1); Tai, Yuping(1,2); Shen, Yijie(3,4); Li, Xinzhong(1,2)
  Source:Optics Letters
  Volume: 49  Issue: 19  DOI: 10.1364/OL.534222  Published: October 1, 2024  
  Abstract:Ray-wave structured vortex beams have attracted increasing attention due to their unique spatial geometric coupling to control complex orbital angular momentum (OAM). Still, current models were constrained by circular symmetry with limited modulation freedom. Herein, we propose a generalized class of ray-wave light fields called Mathieu geometric modes (MGMs) fulfilling the form of a stationary coherent state but based on a set of helical Mathieu modes (HMMs), in which geometrically tunable elliptical accelerating vortices are obtained by tuning their eccentricity-related parameters. MGMs also possess intriguing properties of coordinate transformation, self-healing, and multilayer tunable angular acceleration upon propagation. MGMs have higher degrees of freedom to control spatial accelerating vortices, paving the way for higher-dimensional optical tweezers and complex particle manipulation. © 2024 Optica Publishing Group.
  Accession Number: 20244117178443
• Record 58 of
  
  Title:Site-Selective Synthesis of Bilayer Graphene on Cu Substrates Using Titanium as a Carbon Diffusion Barrier
  
  Author(s):Song, Qiyang(1); Zhang, Youwei(1,2); Chen, Qiao(1); Wu, Su(1); Yan, Xin(3); He, Kai(3); Gao, Guilong(3); Chen, Qiao(4); Wang, Shun(1)
  Source:ACS Applied Materials and Interfaces
  Volume: 16  Issue: 29  DOI: 10.1021/acsami.4c04521  Published: July 24, 2024  
  Abstract:Chemical vapor deposition (CVD) is a widely used method for graphene synthesis, but it struggles to produce large-area uniform bilayer graphene (BLG). This study introduces a novel approach to meet the demands of large-scale integrated circuit applications, challenging the conventional reliance on uniform BLG over extensive areas. We developed a unique method involving the direct growth of bilayer graphene arrays (BLGA) on Cu foil substrates using patterned titanium (Ti) as a diffusion barrier. The use of the Ti layer can effectively control carbon atom diffusion through the Cu foil without altering the growth conditions or compromising the graphene quality, thereby showcasing its versatility. The approach allows for targeted BLG growth and achieved a yield of 100% for a 10 × 10 BLG units array. Then a 10 × 10 BLG memristor array was fabricated, and a yield of 96% was achieved. The performances of these devices show good uniformity, evidenced by the set voltages concentrated around 4 V, and a high resistance state (HRS) to low resistance state (LRS) ratio predominantly around 107, reflecting the spatial uniformity of the prepared BLGA. This study provides insight into the BLG growth mechanism and opens new possibilities for BLG-based electronics. © 2024 American Chemical Society.
  Accession Number: 20243016763020
• Record 59 of
  
  Title:Differentiable design of a double-freeform lens with multi-level radial basis functions for extended source irradiance tailoring
  
  Author(s):Tang, Haisong(1,2); Li, Haoran(1,2); Feng, Zexin(1,2); Luo, Yi(3); Mao, Xianglong(4)
  Source:Optica
  Volume: 11  Issue: 5  DOI: 10.1364/OPTICA.520485  Published: May 20, 2024  
  Abstract:Freeform optics are key for generating prescribed illumination patterns from given sources, which are crucial for solid-state lighting and machine vision illumination. There is an increasing demand for compact freeform optics, which presents a substantial challenge for current design methods since the source dimensions must be considered. Most current extended-source design methods, although requiring profound knowledge of optics and mathematics, focus on the modest goal of obtaining uniform irradiance distributions. We address a more challenging design problem of generating an irradiance distribution of arbitrary shape through a double-freeform lens that can fully encompass the extended source. We propose a differentiable design method whose uniqueness lies in the representation of the double-freeform surfaces using multi-level spherical radial basis functions, which has a natural link to a multi-scale optimization technique. In addition, we employ a sequential unconstrained minimization technology complemented with Lagrange multipliers that add key feasibility constraints on lens shape and size. The proposed method is flexible, general, and efficient in designing highly compact freeform lenses for generating both simple and complex irradiance distributions, as demonstrated through the design examples. This could enable a universal solution to the extended-source design problem. © 2024 Optica Publishing Group.
  Accession Number: 20242116151703
• Record 60 of
  
  Title:Advanced lead-free double perovskites/silica hybrid nanocrystals for highly stable light-emitting diodes
  
  Author(s):Shi, Jindou(1); Wang, Zeyu(2); Xu, Luxia(3); Wang, Junnan(1); Da, Zheyuan(1); Zhang, Chen(1); Ji, Yongqiang(1); Yao, Qing(1); Xu, Youlong(1); Gaponenko, Nikolai V.(4); Tian, Jinshou(3); Wang, Minqiang(1)
  Source:Journal of Materials Chemistry C
  Volume: 12  Issue: 29  DOI: 10.1039/d4tc00585f  Published: May 17, 2024  
  Abstract:The commercial viability of fluorescent materials is critically contingent on their thermal stability. Recent interest has converged on lead-free double perovskites (DPs), renowned for their optical properties mirroring those of traditional lead-based counterparts and superior atmospheric stability. However, these materials encounter significant fluorescence degradation in thermal environments, a challenging scenario given the high temperatures endemic to the surfaces of optoelectronic devices during prolonged operation, detrimentally impacting the fluorescent attributes of lead-free DPs. To address this challenge, in situ synthesis of lead-free DP nanocrystals (NCs) within KIT-6 mesoporous molecular sieves is proposed, yielding Cs2AgIn0.98Bi0.02Cl6@KIT-6 NCs with enhanced optical qualities. Experimental results demonstrate a marked enhancement in the fluorescence thermal stability of these NCs, attributed to the protective KIT-6 shell layer. Subjected to high power operation (100 mA) for 270 minutes, the fabricated orange light-emitting diode (LED) device maintained 80% of initial luminous efficiency, despite the resultant elevated surface temperature of 326.8 K. Therefore, this novel in situ assembly approach significantly bolsters the operational stability of lead-free DPs, paving the way for their potential commercial applications. © 2024 The Royal Society of Chemistry.
  Accession Number: 20242216183179