2023

• Record 433 of
  
  Title:Matter-wave gap solitons and vortices of dense Bose–Einstein condensates in Moiré optical lattices
  
  Author(s):Liu, Xiuye(1,2); Zeng, Jianhua(1,2)
  Source: Chaos, Solitons and Fractals  Volume: 174  Issue: null  Article Number: 113869  DOI: 10.1016/j.chaos.2023.113869  Published: September 2023  
  Abstract:Optical lattices provide a key enabling and controllable platform for exploring new physical phenomena and implications of degenerate quantum gases both in the quantum and nonlinear regimes. Based on the Gross–Pitaevskii/nonlinear Schrödinger equation with competing cubic–quintic nonlinearity, we show, numerically and theoretically, the nonlinear localization of dense Bose–Einstein condensates (BECs) in a novel two-dimensional twisted periodic potential called Moiré optical lattices which, in essence, build a bridge between the perfect optical lattices and aperiodic ones. Our theory reveals that the Moiré optical lattices display a wider second gap and flat-band feature, and support two kinds of localized matter-wave structures like gap solitons and topological states (gap vortices) with vortex charge s=1, all populated inside the finite gaps of the linear Bloch-wave spectrum. We demonstrate, by means of linear-stability analysis and direct perturbed evolutions, that these localized structures have wide stability regions, paving the way for studying flat-band and Moiré physics in shallow optical lattices and for finding robust coherent matter waves therein. The twisted periodic structures can be readily implemented with currently available optical-lattice technique in BECs and nonlinear optics experiments where the results predicted here are observable. © 2023 Elsevier Ltd
  Accession Number: 20233114484079
• Record 434 of
  
  Title:Air Channel Space-Charge-Limited Transistor
  
  Author(s):Shen, Zhihua(1); Li, Qiaoning(1); Wang, Xiao(2); Ge, Bin(1); Wu, Shengli(3); Tian, Jinshou(4)
  Source: IEEE Transactions on Electron Devices  Volume: 70  Issue: 4  Article Number: null  DOI: 10.1109/TED.2023.3241838  Published: April 1, 2023  
  Abstract:A vertical structural air channel transistor with a gate block dielectric layer, which can isolate gate from air channel, was proposed. With the presence of gate block dielectric layer, electrons at the edge of the 2-D electron system (2-DES) formed at gate are prevented to be injected into air channel, which may effectively minish the gate leakage current compared to the conventional vertical structure. The transistor operates in the space-charge-limited (SCL) regime of thermionic emission, which makes it theoretically possess the advantages of high-temperature reliability and low power consumption. Simulation results indicate that this transistor can achieve transconductance of 34.2μS and cutoff frequency of 88.2 GHz by optimizing the dimensional parameters. © 1963-2012 IEEE.
  Accession Number: 20230813626027
• Record 435 of
  
  Title:Quantitative Retrieval of Coherent Transfer Function via Fourier Ptychographic Microscopy
  
  Author(s):Chen, Jiaming(1,2); Pan, An(1,2); Wang, Aiye(1,2); Ma, Caiwen(2,3); Yao, Baoli(1,2)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 52  Issue: 9  Article Number: 0911001  DOI: 10.3788/gzxb20235209.0911001  Published: September 2023  
  Abstract:The performance of an optical imaging system is typically characterized by the intensity Point Spread Function （PSF） or Optical Transfer Function （OTF）. But the Coherent Transfer Function （CTF） is better for describing the coherent optical imaging system. Though the CTF characterizes the complex amplitude transfer properties of the light field， it is hard to measure compared with PSF. Fourier Ptychographic Microscopy （FPM） is a promising computational technique that can obtain both complex amplitude information of an object and the CTF of coherent imaging system， which provides a way to retrieve the CTF. FPM， combining the concept of aperture synthesis and phase retrieval， is a recently developed imaging technique that allows the reconstruction of high-resolution complex images with an extended field of view. By acquiring a series of low-resolution brightfield and darkfield images under inclined illumination and stitching them together in the Fourier domain， FPM can break through the frequency limit of the employed objective determined by its numerical aperture. Consequently， the space-bandwidth product of the optical imaging system can be effectively increased without precise mechanical scanning. The flexibility with low-cost hardware requirements makes FPM a powerful tool particularly potential for imaging biomedical samples in the field of digital pathology. Although many advanced FPM techniques have been proposed to achieve higher data acquisition efficiency and recovery accuracy in the past few years， little is known about the precision， stability， and requirements of the CTF， especially when there are inevitable system errors. If FPM can retrieve high-precision CTF， it will provide a new means for CTF calibration. Therefore， this thesis mainly studies the acquisition of CTF with high precision， stability and efficiency via FPM. In this paper， we investigate the reconstruction quality of the CTF under different system errors with different targeted algorithms and find that the reconstructions of CTF is more robust than the reconstructions of object. In addition， under the condition of good recovery of object function， different objective algorithms can also recover basically the same CTF. Therefore， the CTF recovered by FPM algorithm can be used to quantitatively characterize coherent optical systems. Based on this， we report a sub-region translation method named ST-FPM， which is used in Fourier ptychographic microscopy imaging. Based on the basic assumption that the aberration of adjacent local fields is basically unchanged， asymmetric spatial information is introduced to eliminate the grid noise caused by periodic illumination， which improves the recovery accuracy of CTF and accelerates the convergence speed of CTF reconstruction in limited images. The recovered CTF is deconvolved with incoherent images. And the contrast is additionally improved compared with the traditional FPM. In addition， this method can realize image refocusing without the prior information of defocus. In addition， we study the spatial and frequency domain data redundancy of Fourier ptychographic microscopy to recover the coherent transfer function， and find that at least about 40% spectral overlap rate is needed to accurately reconstruct the coherent transfer function， which is 10% higher than that without aberration. And at least 25 original low-resolution images are needed for the stability of coherent transfer function. Finally， we discuss the necessary conditions for stable CTF reconstruction， and verify the conclusion in simulation and experiment. © 2023 Chinese Optical Society. All rights reserved.
  Accession Number: 20234014824757
• Record 436 of
  
  Title:Label-free and highly-sensitive protamine detection by layer-by-layer assembled chitosan/heparin functionalized optical fiber mode interferometer
  
  Author(s):Yan, Minglu(1); Wang, Ruiduo(1,2); Wang, Qiang(3); Li, Yansong(3); Liu, Beibei(1); Li, Yangyang(1); Jiang, Man(1)
  Source: Sensors and Actuators B: Chemical  Volume: 395  Issue: null  Article Number: 134414  DOI: 10.1016/j.snb.2023.134414  Published: November 15, 2023  
  Abstract:There is a strong requirement for label-free, selective and rapidly detection of Protamine (PRTM) due to that the PRTM and Heparin (Hep) have been widely used in clinical treatment. Here, an optical fiber interferometer biosensor that functionalized by layer-by-layer electrostatic assembled chitosan/heparin (CS/Hep) is proposed for PRTM detection. Experimental results proved that the refractive index (RI) sensitivity is related to thickness of CS/Hep overlayer, which is a key factor of sensor's performance. The CS/Hep polyelectrolyte film coating extend its evanescent filed and can also be used as the signal amplification medium for PRTM detection due to the electrostatic interactions between PRTM and Hep. The optimal sensor that coated with 10 bilayers of CS/Hep, demonstrates RI sensitivity of 435.6 nm/RIU as well as ideal stability, and was chosen for PRTM detection. The CS/Hep based biosensor demonstrates a detection limit of 0.48 μg/mL and sensitivity of 0.1238 nm/(μg/mL) in the linear fitting range. Furthermore, the sensor illustrated ideal selectivity in serum samples and well reusability. Overall, the sensor features with high mechanical strength, ease of fabrication, real-time and label-free. This proposed sensor has potential applications for detecting PRTM in clinical applications. © 2023 Elsevier B.V.
  Accession Number: 20233614690240
• Record 437 of
  
  Title:Flow and heat transfer for the mist/steam two-phase flow in the U-shaped channel with column-row-ribs and solid ribs
  
  Author(s):Jiang, Guangwen(1); Gao, Jianmin(2)
  Source: Applied Thermal Engineering  Volume: 218  Issue: null  Article Number: 119277  DOI: 10.1016/j.applthermaleng.2022.119277  Published: January 5, 2023  
  Abstract:The comparison of flow field and heat transfer characteristics for the new mist/steam working fluid inside the U-shaped internal cooling channel of the gas turbine blades roughed with new V-45 deg. Column-Row-Ribs and V-45 deg. solid ribs are conducted under the limited working conditions in this work. First, the secondary flow vortex and droplets distribution in channels with different turbulators were analyzed. Then, qualitative heat transfer comparison of these two different ribbed channels was conducted. Furthermore, the quantitative analysis of heat transfer enhancement and heat transfer uniformity was presented under the condition of different mist/steam mass ratio (mist/steam) and droplets diameter (D0). Through the analysis, it is seen that the Mainstream Secondary Flow Vortexes in U-shaped channel roughed with 45° V-shaped Column-Row-Ribs has the similar structure as the channel with 45° V-shaped solid ribs. The droplets have a more even distribution in U-shaped channel roughed with 45° V-shaped Column-Row-Ribs than channel with 45° V-shaped solid ribs. And the new Column-Row-Ribs will help to solve the problem that the droplets deposit at the windward side of the solid ribbed channel, which benefits to promote the heat transfer evenness of the heated wall. The results proved that the U-shaped channel with 45° V-shaped Column-Row-Ribs cooled with the mist-steam coolant has better heat transfer characteristics than the 45° V-shaped solid ribs. For the U-shaped channel, there exists a best droplet diameter which can achieve the highest heat transfer enhancement. © 2022 Elsevier Ltd
  Accession Number: 20223812778115
• Record 438 of
  
  Title:Compact and high-reliability fiber-optic open-loop gyroscope enabled by an in-fiber polarizer
  
  Author(s):Chen, Lin(1); Mao, Yuzheng(2); He, Peitong(3); Wang, Hushan(4); Jiang, Biqiang(1); Zhao, Jianlin(1)
  Source: Optics Express  Volume: 31  Issue: 3  Article Number: null  DOI: 10.1364/OE.480935  Published: January 30, 2023  
  Abstract:The performance of an open-loop fiber-optic gyroscope is strongly dependent on the optical characteristics of its polarizer. Here we report the implementation of an in-house fabricated 45° tilted-fiber-grating-based polarizer, for the first time on an ultra-fine diameter polarization-maintaining fiber platform in an open-loop fiber-optic gyroscope. This special in-line polarizer is proven to have the merits of high extinction ratio, broad spectrum, bendability, stretchability, temperature insensitivity, and high reliability, all of which make it a perfect match for practical fiber optic gyros that need to be packaged compactly without affecting performance. Our prototype fiber optic gyroscope has a compact volume of only φ35 × 20 mm2, achieving a bias instability of less than 0.1 °/h, full temperature bias stability of less than 1 °/h, and scale factor linearity of better than 200 ppm. This compact and high-performance fiber gyro enabled by TFG polarizer may promise great potential in the field of automation and control. © 2023 Optica Publishing Group.
  Accession Number: 20230513467399
• Record 439 of
  
  Title:Study on the laser-induced damage characteristics and structure changes of fluorotellurite glass under femtosecond pulsed laser irradiation
  
  Author(s):Wan, Rui(1,2); Li, Xianda(1,2); Ma, Yuan(1,2); Guo, Chen(1,2); Li, Shengwu(1,2); Wang, Pengfei(1,2)
  Source: Journal of Non-Crystalline Solids  Volume: 622  Issue: null  Article Number: 122657  DOI: 10.1016/j.jnoncrysol.2023.122657  Published: December 15, 2023  
  Abstract:TeO2-ZnF2-BaF2-Ta2O5 fluorotellurite glasses have excellent optical properties and stability which makes them promising candidates for mid-infrared (mid-IR) fiber applications. In this work, the properties and structure of fluorotellurite glasses with gradient change of BaF2 content were compared. Under the irradiation of femtosecond (fs) laser, the potential relationship between fs laser-induced damage characteristics, glass composition and structural property were systematically studied. The fs laser-induced damage threshold (FLIDT) of investigated fluorotellurite glass samples increased from 892.45 mJ/cm2 by more than one-third to 1223.84 mJ/cm2 and the attenuation coefficient of multi-pulse FLIDT increases from 7.69 to 25.29 with the increase of [TeO3] content from 0.312 to 0.565 induced by increasing BaF2 content. Further, structural transformation from TeO4 units to TeO3 units in the glass network triggered by fs laser irradiation is confirmed by Raman spectra measurements. This study provides theoretical guidance for tailoring the fs laser damage threshold through glass microstructural modulation by composition optimization, which is of great importance to improve the output power in mid-IR supercontinuum (SC) spectra and rare earth (RE) doped fiber laser systems. © 2023 Elsevier B.V.
  Accession Number: 20233914810267
• Record 440 of
  
  Title:Analysis of Sensing Characteristics of Parallel Fabry-Pérot Interferometer Based on Vernier Effect
  
  Author(s):Luo, Chunhui(1); Chen, Xiaoxu(1); Wu, Shun(1,2)
  Source: Guangxue Xuebao/Acta Optica Sinica  Volume: 43  Issue: 5  Article Number: 0506002  DOI: 10.3788/AOS221550  Published: March 2023  
  Abstract:Objective Optical fiber sensor technology has been extensively applied in gas pressure sensing in the field of industrial and environmental safety monitoring on account of its high sensitivity, compact structure, and immunity to electromagnetic interference. Compared with long-period fiber gratings and anti-resonance waveguides, optical fiber sensors based on the vernier effect generally have greater advantages in terms of sensitivity. The vernier effect is an effective method for amplifying interferometer sensitivity, which is well-known in optical fiber sensing. However, as the harmonic order j increases, vernier spectra deteriorate, namely that the contrast of the external envelope decreases, and the inner envelope disappears. The objective of this work is to generalize the higher-order vernier effect and obtain high sensitivity through experimental exploration and theoretical analysis. In addition, we intend to explore the reasons for the decrease in external envelope contrast and the loss of internal envelopes that affect spectral contrast. We expect to contribute to the extensive application of the high-order harmonic vernier effect and high-sensitivity sensor design. Methods Firstly, we theoretically simulate the higher-order vernier spectrum for j=1, 2, 3, 4. Then, we fabricate four parallel structures of the Fabry-Pérot interferometers experimentally and study the corresponding vernier spectra. After that, we investigate the effect of the difference in light intensity between the sensing cavity and the reference cavity on the vernier spectrum by changing the light intensity difference between the two cavities. In addition, we analyze various parameters that affect the vernier magnification factor and design a highly sensitive fiber-based gas pressure sensor. Results and Discussions On the basis of a parallel Fabry-Pérot interferometer, this paper compares the theoretical simulations (Fig. 2) and the experimental results (Fig. 3) of vernier spectra for j=1, 2, 3, 4. The comparison shows that they are consistent, which indicates the vernier effect is valid in the experiment. After that, we simulate the spectra corresponding to different light intensities of the sensing cavity and the reference cavity. It is found that with the increase in the light intensity difference between the two cavities, the contrast of the external envelope decreases, and the internal envelope disappears (Fig. 5). Then, we fundamentally explain the deterioration of the vernier spectrum when the higher-order harmonic vernier effect is applied in the experiment (Fig. 6). In addition, the factors affecting the vernier magnification are discussed from the aspects of a higher value of j and a lower detuning ratio. After that, we put forward reasonable suggestions for obtaining higher magnification when applying the vernier effect in gas pressure sensing. Furthermore, a sample corresponding to the first-order harmonic vernier effect is produced for the gas pressure test. At room temperature, it enjoys gas pressure sensitivity of 152 pm/kPa, a corresponding magnification factor of 35.3, and linearity of 99% in the range of 10-190 kPa (Fig. 4). Conclusions This paper studies the higher-order harmonic vernier effect and proposes a method to improve the interference fringe contrast for the external vernier envelope, which is verified by experiments. The reason for the reduction in the vernier spectrum contrast is the reduction in the imbalance of light intensity between the sensing and the reference cavities. The application demonstrates that with the increase in the light intensity difference between the two cavities, the vernier spectrum becomes more susceptible to the quality or noise of the light source. This leads to weaker visibility of the envelope for higher harmonic orders. In addition, we analyze various experimental parameters so as to obtain high sensitivity and demonstrate a parallel Fabry-Pérot interferometer with gas pressure sensitivity of 152 pm/kPa, linearity of 99%, and a magnification factor of 35. 3 in the range of 10-190 kPa. © 2023 Chinese Optical Society. All rights reserved.
  Accession Number: 20231914068543
• Record 441 of
  
  Title:Femtosecond laser-induced refractive index change and phase-type Fresnel zone plate in fluorotellurite glass
  
  Author(s):Li, Xianda(1,2); Liu, Feng(3); Wan, Rui(1,2); Li, Weinan(1); Wang, Pengfei(1)
  Source: Optics and Laser Technology  Volume: 161  Issue: null  Article Number: 109216  DOI: 10.1016/j.optlastec.2023.109216  Published: June 2023  
  Abstract:We report a phase-type Fresnel zone plate (FZP) fabricated by femtosecond (fs) laser-induced refractive index change (RIC), which was embedded in a newly developed fluorotellurite glass. The effect of laser direct-writing parameters on the morphology of the laser-induced structures was studied and negative RIC was observed. A maximum RIC of 4.42×10-3 was achieved at laser inscription energy of 0.13 µJ. Additionally, structure change from TeO4 units to TeO3- units triggered by fs laser irradiation is verified by Raman spectra measurements for the first time, to the best of our knowledge, and demonstrated to be a vital factor for the negative RIC. On this basis, we firstly fabricated a two-level phase-type FZP designed to work at 1340 nm inside such fluorotellurite glass. The phase-type FZP exhibits strong IR beam focusing and excellent imaging capabilities with a resolution of 128 line pairs per millimeter (lp/mm). This study reveals the facts that such novel fluorotellurite glass has good processibility with fs laser direct writing and made it a potential alternative material for micro-optics in NIR applications. © 2023 Elsevier Ltd
  Accession Number: 20230613539853
• Record 442 of
  
  Title:Calibration of spatially modulated snapshot imaging polarimeter based on phase-shift interferometry
  
  Author(s):Tang, Jinfeng(1); Jia, Chenling(2); Zhang, Jin(1); Jiang, Ming(1); Pan, Yangliu(1); Jiang, Siyue(1); Hu, Baoqing(3); Cao, Qizhi(1,4); Jin, Mingwu(5)
  Source: Applied Optics  Volume: 62  Issue: 12  Article Number: null  DOI: 10.1364/AO.483989  Published: April 20, 2023  
  Abstract:The snapshot imaging polarimeters (SIPs) using spatial modulation have gained increasing popularity due to their capability of obtaining all four Stokes parameters in a single measurement. However, the existing reference beam calibration techniques cannot extract the modulation phase factors of the spatially modulated system. In this paper, a calibration technique based on a phase-shift interference (PSI) theory is proposed to address this issue. The proposed technique can accurately extract and demodulate the modulation phase factors through measuring the reference object at different polarization analyzer orientations and performing a PSI algorithm. Using the snapshot imaging polarimeter with modified Savart polariscopes as an example, the basic principle of the proposed technique is analyzed in detail. Subsequently, the feasibility of this calibration technique was demonstrated by a numerical simulation and a laboratory experiment. This work provides a different perspective for the calibration of a spatially modulated snapshot imaging polarimeter. © 2023 Optica Publishing Group.
  Accession Number: 20231914075718
• Record 443 of
  
  Title:A label-free biosensor for pepsin detection based on graphene oxide functionalized micro-tapered long period fiber grating
  
  Author(s):Kang, Xin(1,2); Wang, Ruiduo(1); Jiang, Man(2); Li, Erkang(2); Li, Yarong(2); Wang, Tianqi(2); Ren, Zhaoyu(2)
  Source: Sensors and Actuators Reports  Volume: 5  Issue: null  Article Number: 100139  DOI: 10.1016/j.snr.2023.100139  Published: June 2023  
  Abstract:The rapid and sensitive detection of pepsin plays an important role in clinical and medical practice. A label-free and sensitive micro-tapered long-period fiber grating (MTLPFG) sensor that functionalized by graphene oxide (GO) was proposed for pepsin detection. MTLPFG was fabricated with CO2 laser heating and tapered to form a series of periods, and the GO that activated oxygen groups by EDC/NHS was deposited onto MTLPFG surface. On account of large specific surface area and oxygen containing groups of GO, the biomolecules can be adsorbed on the GO surface through amide groups and π-π stacking. The spectrum variation trend during sensing process obeys Langmuir absorption mode, which illustrates biomolecule adsorption on GO layer. The bare MTLPFG and GO-MTLPFG separately demonstrate the limit of detection (LOD) of 104.6 ng/ml and 25.79 ng/ml, which corresponding to the effectively detection range of 1–1000 ng/ml. Combination of GO and optical fibers exhibit great adaptive capacity to the biosensors, and provides inspirations for biochemical sensing applications. © 2023 The Authors
  Accession Number: 20230213380160
• Record 444 of
  
  Title:Long period fiber grating sensor coated with MXene (Ti3C2TX) functionalized by poly-levodopa for rapid detection of Cu2+
  
  Author(s):Yan, Minglu(1); Li, Yarong(1); Li, Yangyang(1); Liu, Beibei(1); Wang, Ruiduo(2); Jiang, Man(1)
  Source: Optik  Volume: 288  Issue: null  Article Number: 171198  DOI: 10.1016/j.ijleo.2023.171198  Published: October 2023  
  Abstract:An optical sensor based on long period fiber grating (LPFG) modified by MXene-polymer composites was proposed to detect Cu2+. Ti3C2Tx is prepared by etching aluminum with hydrofluoric acid (HF) from the Ti3AlC2. MXene-based materials demonstrate the potential to adsorb multi-pollutants, but the adsorption performance is limited. Mussel-inspired poly-levodopa (PDOPA) modified Ti3C2Tx, with a simple and eco-friendly reaction process, has been proven to enhance the adsorption capacity for Cu2+. The resonance spectrum of LPFG is sensitive to changes of refractive index (RI) aroused by Cu2+ adsorption on the sensing film. Thus, the Cu2+ sensing performance of the LPFG sensor coated with Ti3C2Tx and PDOPA-Ti3C2TX was separately investigated. The best sensitivity of the PDOPA-Ti3C2TX-LPFG was measured to be 3.48 × 10−4 nm/ppb (0–103 ppb) and the detection limit was determined to be 10.34 ppb (0.162 μM), which was obviously better than the results of 1.80 × 10−4 nm/ppb and 25 ppb (0.393 μM) with only Ti3C2Tx coated. Moreover, the stability and reusability of the sensor were also evaluated. This sensor provides a new approach for metal ions detection in the water environment. © 2023 Elsevier GmbH
  Accession Number: 20233014448068