2019

• Record 505 of
  
  Title:Signal enhancement of laser-induced breakdown spectroscopy on non-flat samples by single beam splitting
  
  Author(s):Lei, Bingying(1,2); Wang, Jing(1,2); Li, Jing(1,2); Tang, Jie(1); Wang, Yishan(1,2); Zhao, Wei(1,2); Duan, Yixiang(1,3)
  Source: Optics Express  Volume: 27  Issue: 15  DOI: 10.1364/OE.27.020541  Published: July 22, 2019  
  Abstract:A single-beam-splitting approach was employed to enhance the signal intensity of LIBS under the extreme condition of laser beam grazing the surface of non-flat samples. Examining the time-integrated emission spectra shows that ISplit ISingle enhancement factors of 2.5 and 3.5 were achieved at the laser energy of 33 mJ for aluminium alloy and brass, respectively. This factor first increases, reaches its maximum at 33 mJ, and drops gradually with the laser energy further increased. The mechanisms behind the enhanced optical emission and the enhancement factor evolution are discussed by using the proposed laser ablation model and laser-supported detonation (LSD) wave model, respectively. Examining the time-resolved emission spectra show that enhancement effect exists across all the plasma expansion process and the split beam mode allows for a longer plasma lifetime. A remarkable feature is that the trailing phenomenon emerging in the single beam mode vanishes due to the interaction between the plasmas generated by the grazing incident and normally incident laser beams in the split beam mode. The underlying cause is probably that the plasma plume produced by the normally incident laser beam prevents the grazing incident laser beam from further propagating and ablating the sample surface below. These findings not only give an insight into the plasma generation and evolution at grazing incidence of laser beam on sample surface but also provide a more reliable method for outdoor LIBS measurement of irregular samples. © 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
  Accession Number: 20193107261607
• Record 506 of
  
  Title:Low-cost temperature- And strain-insensitive twist sensor based on a hybrid fiber grating structure
  
  Author(s):Guo, Xi(1); Xing, Zhikun(1); Qin, Huabao(1); Sun, Qizhen(1); Wang, Hushan(2); Liu, Deming(1); Zhang, Lin(3); Yan, Zhijun(1,2,3)
  Source: Applied Optics  Volume: 58  Issue: 16  DOI: 10.1364/AO.58.004479  Published: June 1, 2019  
  Abstract:We proposed and experimentally demonstrated a temperature- and strain-insensitive twist sensor based on a hybrid fiber grating structure, in which the hybrid grating structure is constructed with a 45°-tilted fiber grating and a chirped fiber Bragg grating UV-inscribed in a single-mode fiber in series. The sensing performance has been evaluated by experimental and numerical analyses, which are in good consistency. The experimental results show that the hybrid-grating-structure-based twist sensor has a maximum twist sensitivity up to 15.037 dB/rad. Moreover, due to the invariability of the fiber birefringence and the state of polarization of the input light, such sensor has intrinsically low temperature and strain sensitivities of 7.86 × 10−3 dB∕°C and 6.7 × 10−5 dB∕μΕ, corresponding to the maximum twist measurement error resulting from temperature and strain of 5.2 × 10−4 rad∕°C and 4.5 × 10−6 rad∕μΕ, respectively. © 2019 Optical Society of America
  Accession Number: 20192307009700
• Record 507 of
  
  Title:Logic NOT gates of the intensity–noise correlation and squeezing in a diamond nitrogen-vacancy center
  
  Author(s):Liu, Yang(1,3); Raza, Faizan(2); Li, Kangkang(2); Ullah, Habib(2); Zhang, Yanpeng(2); Zhang, Wenfu(1,3); Zhao, Wei(1,3)
  Source: Journal of the Optical Society of America B: Optical Physics  Volume: 36  Issue: 10  DOI: 10.1364/JOSAB.36.002727  Published: 2019  
  Abstract:Color defects in a diamond nitrogen-vacancy (NV) center represent an important physical system for emergent quantum technologies such as logic gates and registers at room temperature. We realized an optical logic NOT gate by inducing a phase shift in a diamond NV center under nonlinear Kerr effect of spontaneous parametric four-wave mixing (SP-FWM). Also, we discussed the intensity–noise correlation and intensity-difference squeezing of SP-FWM and composite signals (SP-FWM+fluorescence) under self-phase modulation (SPM) and cross-phase modulation (XPM) induced by the nonlinear Kerr effect in V-type and double V-type atomic systems. Our experimental results provide an advanced technique of switching contrast by approximately 90%. Different parameters, such as the power of input laser beam and boxcar gate position, were also configured to control the SPM and XPM, which determine the switching phenomenon for correlation and squeezing. © 2019 Optical Society of America.
  Accession Number: 20194107526649
• Record 508 of
  
  Title:Simulation and observation for volume emission rates emitted from O2(0-1) and O(1S) nightglow in northwest China
  
  Author(s):Tang, Yuanhe(1); Sun, Peng(1); Gao, Haiyang(2); Cui, Jin(1); Li, Zijian(1); Wang, Haoxuan(1); Lv, Huan(1); Jia, Min(1); Liu, Hanchen(3); Li, Cunxia(1); Liu, Qingsong(4)
  Source: Applied Optics  Volume: 58  Issue: 4  DOI: 10.1364/AO.58.001093  Published: February 1, 2019  
  Abstract:Being susceptible to the change of atmospheric conditions, the volume emission rate (VER) is very suitable to be used as a light source by passive remote sensing for measuring atmospheric wind and temperature. Thus, the VERs emitted from O20‐1 and O1S of the nightglow at 80–120 km are studied in this paper. Based on the Naval Research Laboratory Mass Spectrometer Incoherent Scatter (NRLMSISE-00) model data and the ground-based airglow imaging interferometer (GBAII) instrument observation for a local time and place, simulated VER profiles represented by four layers are obtained for the nightglow of O20‐1 and O1S. The O20‐1 nightglow model peak values at 94 km on 6 December 2013 and 8 November 2011 are 8111 photons · cm−3 · s−1 and 8406 photons · cm−3 · s−1, respectively; however, the O1S VER peak at a higher altitude of about 96 km on 18 December 2011 is only 338 photons · cm−3 · s−1. The upper atmospheric VER values have been derived to transfer into the ground–based detected column intensities by our GBAII prototype. The calculated column integrated emission rates (IERs) of O20‐1 for 0° and 45° zenith angles are 1.48 × 107 and 1.91 × 107 photons · cm−2 · s−1, respectively; the calculated column IERs of O1S are 5.53 × 105 and 7.03 × 105 photons · cm−2 · s−1, respectively. Correspondingly, the detected column IERs obtained by GBAII are 2.43 × 107 for O20‐1 and 6.57 × 105 photons · cm−2 · s−1 for O1S. © 2019 Optical Society of America.
  Accession Number: 20190606470278
• Record 509 of
  
  Title:Truncated Gaussian-Bessel beams for short-pulse processing of small-aspect-ratio microchannels in dielectrics
  
  Author(s):Liu, X.(1,2,3); Li, Q.(3); Sikora, A.(3); Sentis, M.(3); Utéza, O.(3); Stoian, R.(4); Zhao, W.(1); Cheng, G.(1); Sanner, N.(3)
  Source: Optics Express  Volume: 27  Issue: 5  DOI: 10.1364/OE.27.006996  Published: 2019  
  Abstract:In order to control the length of micro-channels ablated at the surface of dielectrics, we use annular filtering apertures for tailoring the depth of focus of micrometric Gaussian-Bessel beams. We identify experimentally and numerically the appropriate beam truncation that promotes a smooth axial distribution of intensity with a small elongation, suitable for processing micro-channels of small aspect ratio. Single-shot channel fabrication is demonstrated on the front surface of a fused silica sample, with sub-micron diameter, high-quality opening, and depth of few micrometers, using 1 ps low-energy ( © 2019 Optical Society of America.
  Accession Number: 20191106643736
• Record 510 of
  
  Title:Wideband and compact TM-pass polarizer based on hybrid plasmonic grating in LNOI
  
  Author(s):Yu, Wenqi(1,2); Dai, Shuangxing(1,2); Zhao, Qinfeng(1,3); Li, Jinye(1,2); Liu, Jianguo(2)
  Source: Optics Express  Volume: 27  Issue: 24  DOI: 10.1364/OE.27.034857  Published: 2019  
  Abstract:Based on the transverse electric (TE)/transverse magnetic (TM) polarization diversity in plasmonic Bragg gratings, a compact TM-pass/TE-stop polarizer is theoretically proposed on thin-film lithium niobate on insulator (LNOI) platforms. By introducing a large misalignment between metal gratings on both sides of the LNOI waveguide, we demonstrate a polarizer with a high extinction ratio of 20 dB, a low insertion loss of 2.5 dB, a wide waveband from 1.48 to 1.62 µm, and a compact size of only 23 µm on simulation. © 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
  Accession Number: 20194907771939
• Record 511 of
  
  Title:Robust and flexible method for calibrating the focal length of on-orbit space zoom camera
  
  Author(s):Zhang, Gaopeng(1,2); Zhao, Hong(1); Yang, Hongtao(2); Hong, Yang(3); Ma, Yueyang(1); Gu, Feifei(4)
  Source: Applied Optics  Volume: 58  Issue: 6  DOI: 10.1364/AO.58.001467  Published: February 20, 2019  
  Abstract:For the on-orbit space zoom camera, the camera focal length is in a constant process of change; accordingly, compared with calibrating other camera intrinsic parameters, calibrating the focal length has a practical significance for the space zoom camera. With the vanishing points obtained from the solar panel of human-made space satellites, this paper introduces a focal length self-calibration method for the on-orbit space zoom camera. First, the geometrical relationship and infinite homography of vanishing points at various camera positions are used to derive the method. To improve the accuracy and robustness performance of this approach, an optimization method is then proposed to nonlinearly optimize the camera focal length. Finally, simulation and real physical experiments demonstrate that the proposed method is flexible and accurate with good anti-noise interference and real-time capacity. The method proposed in this paper makes more realistic sense for a number of important space tasks. © 2019 Optical Society of America.
  Accession Number: 20190806543466
• Record 512 of
  
  Title:Multi-view object topography measurement with optical sectioning structured illumination microscopy
  
  Author(s):Ren, Feifei(1,2); Wang, Zhaojun(1,2); Qian, Jia(1,2); Liang, Yansheng(1); Dang, Shipei(1,2); Cai, Yanan(1,2); Bianco, Piero R.(3); Yao, Baoli(1); Lei, Ming(1)
  Source: Applied Optics  Volume: 58  Issue: 23  DOI: 10.1364/AO.58.006288  Published: August 10, 2019  
  Abstract:Various optical instruments have been developed for three-dimensional (3D) surface topography, including the white light interference, reflectance confocal microscopes, and digital holographic microscopes, etc. However, the steep local slope of objects may cause the light to be reflected in a way that it will not be captured by the objective lens because of the finite collection angle of the objective. To solve this "shadow problem," we report a method to enlarge the collection angle range of optical sectioning structured illumination microscopy by capturing sectioned images of the objects from multiple angle of views. We develop a multi-view image fusion algorithm to reconstruct a single 3D image. Using this method, we detect previously invisible details whose slopes are beyond the collection angle of the objective. The proposed approach is useful for height map measurement and quantitative analyses in a variety of fields, such as biology, materials science, microelectronics, etc. © 2019 Optical Society of America.
  Accession Number: 20193307307652
• Record 513 of
  
  Title:Fano-like resonance in an all-in-fiber structure
  
  Author(s):Jiang, Biqiang(1,2); Gan, Xuetao(1); Gu, Linpeng(1); Hao, Zhen(1); Wang, Shouheng(1); Bi, Zhixuan(1); Zhang, Lin(2); Zhou, Kaiming(2,3); Zhao, Jianlin(1)
  Source: IEEE Photonics Journal  Volume: 11  Issue: 5  DOI: 10.1109/JPHOT.2019.2936485  Published: October 2019  
  Abstract:We achieve Fano-like resonances in an all-in-fiber structure embedded with an in-line Mach-Zehnder interferometer (MZI). A fiber Bragg grating is inserted into MZI’s one arm to form a resonance, which functions as the discrete state of the Fano-like resonance to couple with the continuum propagating mode of MZI in the fiber core. A theoretical model predicts the controllable resonance lineshape by changing the phase difference between the MZI’s two interference pathways. Fano-like resonances with an extinction ratio over 20 dB are experimentally observed, which are reliably tuned into Lorentzian and electromagnetically induced transparency-like resonances by versatile methods. The realization of Fano-like resonances with broad tunability in this all-in-fiber structure holds potentials in fiber-based applications of sensing, signal processing and nonlinear optics. © 2019 Institute of Electrical and Electronics Engineers Inc.. All rights reserved.
  Accession Number: 20212310450700
• Record 514 of
  
  Title:Single acousto-optic tunable filter based double filtering imaging system
  
  Author(s):Zhang, Xiaofa(1); Sheng, Zhenfei(1); Chen, Yaqi(1); Zhang, Chunguang(1,2); Wang, Hao(1,2); Huang, Xi(1,2); Tan, Zhiwei(1); Qiu, Weijie(1); Wang, Pengchong(1,2); Liu, Wenyao(3); Duan, Maoqiang(1,4); Huang, Xiaoli(1,5); Zheng, Ruoling(1); Zeng, Xueqing(1); Lai, Rongcheng(1); Yu, Jiaying(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11170  Issue:   DOI: 10.1117/12.2533586  Published: 2019  
  Abstract:The double filtering system based on single crystal acousto-optic tunable filter (AOTF) in order to improve spectral resolution and reduce side lobe is designed and demonstrated. The effects of single filtering and double filtering on AOTF performance are analyzed. Furthermore, the proposed double filtering technology has the characteristics of high speed, strong stability, flexible tuning, narrow bandwidth and multi-wavelength selection. In this experiment, the spectral bandwidth, side lobe and diffraction efficiency of single filtering and single crystal double filtering in visible range are measured. A double optical wedge compensator is set up at the exit of the double filtering experiment system to compensate the diffracted light drift caused by chromatic aberration. In conclusion, the experimental method of double filtering based on single crystal of tellurium dioxide is better than that of single filtering in spectral resolution and side lobe suppression. © 2019 SPIE.
  Accession Number: 20193107262596
• Record 515 of
  
  Title:Hyperspectral microscopic imaging of skin squamous cell carcinoma
  
  Author(s):Sheng, Zhenfei(1); Zhang, Xiaofa(1); Qiu, Zelong(1); Zhang, Chunguang(1,2); Wang, Hao(1,2); Huang, Xi(1); Tan, Zhiwei(1); Qiu, Weijie(1); Wang, Pengchong(1,2); Liu, Wenyao(3); Duan, Maoqiang(1,4); Huang, Xiaoli(1,5); Liu, Yiping(1); Xing, Yuwei(1); Lin, Binbin(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11170  Issue:   DOI: 10.1117/12.2533591  Published: 2019  
  Abstract:Acousto-optic tunable filter (AOTF) is a new type of light splitter with fast tuning, stable structure and portability. In this paper, a hyperspectral microscopic imaging system is constructed by combining non-collinear AOTF with optical inverted microscopy. The feasibility of data augmentation based on hyperspectral images for object detection of skin squamous cell carcinoma is studied. The hyperspectral images collected from unstained sections of skin squamous cell carcinoma are processed into dataset. At the same time, the mature open source object detection model is selected and trained for 20,000 times. Using the trained model to detect the lesion area of other unstained sections, it is found that the model trained by hyperspectral image dataset has a good ability to distinguish the non-lesion area, and there is no false detection. And the model has a relatively accurate detection ability for large lesion area, but the results of the model for small lesion area are not ideal. After analysis, it is considered that the number of samples can be increased firstly, especially in small lesions, and the same to the hyperspectral images. In addition, the model for lesion detection can be further optimized. By increasing the complexity of the model, the model can learn more details and information in the image during the training process. The preliminary results of the experiment prove that hyperspectral imaging is feasible for data augmentation of lesion object detection dataset. This paper provides a new method for the object detection data augmentation of skin squamous cell carcinoma. © 2019 SPIE.
  Accession Number: 20193107262599
• Record 516 of
  
  Title:Thermal hydraulic performance of a microchannel heat sink for cooling a high-power diode laser bar
  
  Author(s):Wu, Di-Hai(1,2,3); Zah, Chung-En(2); Liu, Xingsheng(2)
  Source: Applied Optics  Volume: 58  Issue: 8  DOI: 10.1364/AO.58.001966  Published: 2019  
  Abstract:Numerical and analytical methods are employed to investigate the thermal and fluid flow performance of a microchannel heat sink for cooling a high-power diode laser bar. Heat transfer characteristics and pressure drop in the microchannel under different flow rates are studied. A thermal resistance network, which is proved to have less than 5.4% error, is proposed to characterize the resistance components for the microchannel heat sink. Both numerical modeling and thermal resistance network analysis are verified by experimental results based on the wavelength shift method. Two new heat sinks with more uniform temperature distribution for laser emitters compared with the existing design are presented, and their performance is validated by numerical modeling and spatially resolved spectrum measurements. © 2019 Optical Society of America
  Accession Number: 20191106637393