2020

• Record 517 of
  
  Title:The Innovation: A Journal to See the Unseen and Change the Unchanged
  
  Author(s):Chen, Ke(1); Huang, Tao(2); Liu, Enke(3); Lu, Yuyuan(4); Huo, Zhigang(5); Mi, Lei(6); Zhang, Wei(7); Frazer, Ian(8)
  Source: Innovation  Volume: 1  Issue: 1  DOI:   Published: May 21, 2020  
  Abstract:null
  Accession Number: 20230813629929
• Record 518 of
  
  Title:High efficiency ultrafast water-window harmonic generation for single-shot soft X-ray spectroscopy
  
  Author(s):Fu, Yuxi(1,4); Nishimura, Kotaro(1,2); Shao, Renzhi(3); Suda, Akira(2); Midorikawa, Katsumi(1); Lan, Pengfei(3); Takahashi, Eiji J.(1)
  Source: Communications Physics  Volume: 3  Issue: 1  DOI: 10.1038/s42005-020-0355-x  Published: December 1, 2020  
  Abstract:Fully coherent, soft X-ray attosecond pulses are now available through high-order harmonic generation (HHG); however, the output energy is insufficient for various applications, such as attosecond-scale soft X-ray nonlinear experiments, the seeding of soft X-ray free-electron lasers, attosecond-pump-attosecond-probe spectroscopies, and single-shot imaging. In this paper, we combine a newly developed TW class mid-infrared femtosecond laser and a loose focusing geometry for HHG. A soft X-ray harmonic beam up to the water window region is demonstrated, which is more than 100 times intense compared to previous works. We achieve a high conversion efficiency, low beam divergence and a significantly reduced medium gas pressure. As the first application, we demonstrate near edge X-ray absorption fine structure experiments with clear fine absorption spectra near the K- and L-edges observed. The robust energy scaling method on HHG opens the door for demonstrating single-shot absorption spectrum and live-cell imaging with a femtosecond time resolution. © 2020, The Author(s).
  Accession Number: 20202408807662
• Record 519 of
  
  Title:Spectroscopic Imaging of Cutaneous Squamous Cell Carcinoma Based on Acousto-Optic Filtering
  
  Author(s):Sheng, Zhen-Fei(1); Zhang, Chun-Guang(1); Qiu, Ze-Long(1); Wang, Hao(1,2); Zhang, Xiao-Fa(1); Huang, Xi(1); Tan, Zhi-Wei(1); Qiu, Wei-Jie(1); Wang, Peng-Chong(1,2); Liu, Wen-Yao(3); Duan, Mao-Qiang(1,4); Huang, Xiao-Li(1,5); Huang, Zu-Fang(1); Liu, Yi-Ping(1); Xing, Yu-Wei(1); Lin, Bin-Bin(1)
  Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis  Volume: 40  Issue: 1  DOI: 10.3964/j.issn.1000-0593(2020)01-0034-07  Published: January 1, 2020  
  Abstract:Noncollinear acousto-optic tunable filter (AOTF) based on TeO2 is a type of good light splitting device with the electric tuning. Because of its advantages of compact size, high stability, fast tuning, and being easy to carry out, it has high practical application value in hyperspectral imaging field. In this study, a hyperspectral microscopic imaging system was built by combining noncollinear AOTF with optical inverted microscope. In the range of visible light, the hyperspectral imaging of cutaneous squamous cell carcinoma was studied, and the spectra and the corresponding microscopic images at a series of optical central wavelengths were got. The performance of the hyperspectral imaging system was tested. The results shown that the bandwidth of the diffracted light in the range of 110~180 MHz was only 1.28~2.84 nm, which indicated that the AOTF in this study had a high spectral resolution with more than 102 spectral channels, and it could meet the needs of hyperspectral microscopic imaging and accurate identification of biological tissue structure. The system used higher quality TeO2 crystal, higher quality double balsaming lens and optimized RF driver to effectively depress the sidelobe of the diffraction spectrum. The tuning relationship between the acoustic frequency and the diffracted optical wavelength, and the relationship between the spectral bandwidth and the acoustic frequency were analyzed. The experimental results were in good agreement with the related the theoretical calculation. The experimental results shown the high image quality of the system because no obvious image shift with the optical wavelength was observed. By comparing the microscopic images of the cutaneous squamous cell carcinoma with different diffraction central wavelengths, the images were also the clearest at 522.52 nm, and the details of the cutaneous squamous cell carcinoma could be distinguished obviously. The difference of the whole brightness and the transmission difference coefficient with the optical wavelength were studied, and the regulations were agreed with the intuitive observation. Through the analysis of the image edge extraction, the results shown that 497.87~551.29 nm can be used to observe and study the cutaneous squamous cell carcinoma with a bright whole field of vision, meanwhile, the results also shown that 509.69~527.59 nm was the best window for accurate identification and analysis of cutaneous squamous cell carcinoma. This study provided a new method for the simple, flexible and rapid detection and diagnosis of human cutaneous squamous cell carcinoma. © 2020, Peking University Press. All right reserved.
  Accession Number: 20200708156144
• Record 520 of
  
  Title:Enhanced optical four-wave-mixing in integrated ring resonators with graphene oxide films
  
  Author(s):Moss, David J.(1); Wu, Jiayang(1); Xu, Xingyuan(1); Yang, Yunyi(1,2); Jia, Linnan(1); Zhang, Yuning(1); Chu, Sai Tak(3); Little, Brent E.(4); Morandotti, Roberto(5,6); Jiao, Baohua(1,2); Qu, Yang(1)
  Source: TechRxiv  Volume:   Issue:   DOI: 10.36227/techrxiv.11859429  Published: February 16, 2020  
  Abstract:Layered two-dimensional (2D) graphene oxide (GO) films are integrated with micro-ring resonators (MRRs) to experimentally demonstrate enhanced nonlinear optics in the form of four-wave mixing (FWM). Both uniformly coated and patterned GO films are integrated on CMOS-compatible doped silica MRRs using a large-area, transfer-free, layer-by-layer GO coating method together with photolithography and lift-off processes, yielding precise control of the film thickness, placement, and coating length. The high Kerr nonlinearity and low loss of the GO films combined with the strong light-matter interaction within the MRRs results in a significant improvement in the FWM efficiency in the hybrid MRRs. Detailed FWM measurements are performed at different pump powers and resonant wavelengths for the uniformly coated MRRs with 1−5 layers of GO as well as the patterned devices with 10−50 layers of GO. The experimental results show good agreement with theory, achieving up to ~7.6-dB enhancement in the FWM conversion efficiency (CE) for an MRR uniformly coated with 1 layer of GO and ~10.3-dB for a patterned device with 50 layers of GO. By fitting the measured CE as a function of pump power for devices with different numbers of GO layers, we also extract the dependence of GO’s third-order nonlinearity on layer number and pump power, revealing interesting physical insights about the evolution of the layered GO films from 2D monolayers to quasi bulk-like behavior. These results confirm the high nonlinear optical performance of integrated photonic resonators incorporated with 2D layered GO films. © 2020, CC BY.
  Accession Number: 20220138338
• Record 521 of
  
  Title:All-fiber phase modulator and switch based on local surface plasmon resonance effect of the gold nanoparticles embedded in gel membrane
  
  Author(s):Luo, Meng(1); Yang, Xinghua(1); Teng, Pingping(1); Liu, Zhihai(1); Yang, Jun(1); Kong, Depeng(2); Gao, Danheng(1); Li, Zhanao(1); Wen, Xingyue(1); Yu, Ximiao(1); Yuan, Libo(1,3); Li, Kang(4); Bowkett, Mark(4); Copner, Nigel(4); Wang, Xiaozhang(5)
  Source: Applied Optics  Volume: 59  Issue: 33  DOI: 10.1364/AO.406268  Published: November 20, 2020  
  Abstract:All-fiber modulators and switches have drawn great interest in the photonics domain, and they are applied in viable photonic and optoelectronic devices. In this work, with the assistance of an agarose membrane, aspherical gold nanoparticles are embedded on the surface of the microfiber treated with the piranha solution. An all-fiber Mach–Zehnder interferometer was used to realize a low-cost, low-loss, and conveniently prepared all-fiber phase modulator. By taking advantage of the local surface plasmon resonance effect of gold nanoparticles embedded in the agarose membrane, under the excitation of near-infrared region light, the gold nanoparticles were excited to change the effective refractive index of one arm of the Mach–Zehnder interferometer. A maximum phase shift of ∼6π at 1550 nm was obtained from the device. In addition, an all-optical switch was achieved with a rising edge time of 47 ms and falling edge time of 14 ms. The proposed all-fiber modulator and switch based on the local surface plasmon resonance effect of gold nanoparticles embedded in agarose membrane will provide great potential in all-optical fiber systems. © 2020 Optical Society of America.
  Accession Number: 20205109656842
• Record 522 of
  
  Title:Hyperspectral deep convolution anomaly detection based on weight adjustment strategy
  
  Author(s):Chong, Dan(1,2); Hu, Bingliang(1); Gao, Xiaohui(1); Gao, Hao(3); Xia, Pu(1); Wu, Yinhua(4)
  Source: Applied Optics  Volume: 59  Issue: 31  DOI: 10.1364/AO.400563  Published: November 1, 2020  
  Abstract:Hyperspectral anomaly detection has garnered much research in recent years due to the excellent detection ability of hyperspectral remote sensing in agriculture, forestry, geological surveys, environmental monitoring, and battlefield target detection. The traditional anomaly detection method ignores the non-linearity and complexity of the hyperspectral image (HSI), while making use of the effectiveness of spatial information rarely. Besides, the anomalous pixels and the background are mixed, which causes a higher false alarm rate in the detection result. In this paper, a hyperspectral deep net-based anomaly detector using weight adjustment strategy (WAHyperDNet) is proposed to circumvent the above issues. We leverage three-dimensional convolution instead of the two-dimensional convolution to get a better way of handling high-dimensional data. In this study, the determinative spectrum–spatial features are extracted across the correlation between HSI pixels. Moreover, feature weights in the method are automatically generated based on absolute distance and the spectral similarity angle to describe the differences between the background pixels and the pixels to be tested. Experimental results on five public datasets show that the proposed approach outperforms the state-of-the-art baselines in both effectiveness and efficiency. © 2020 Optical Society of America
  Accession Number: 20204709511541
• Record 523 of
  
  Title:Real-time continuous calibration method for an ultraviolet camera
  
  Author(s):Wu, Kuijun(1); Feng, Yutao(2); Xiong, Yuanhui(3,4); Duan, Weimin(3,4); Yu, Guangbao(3,4); Li, Faquan(3)
  Source: Optics Letters  Volume: 45  Issue: 24  DOI: 10.1364/OL.410635  Published: December 15, 2020  
  Abstract:The accuracy of SO2 cameras is significantly determined by the ability to obtain an accurate calibration. This work presents a real-time continuous calibration method for SO2 cameras with a moderate resolution spectrometer by taking realistic radiative transfer into account. The effectiveness and accuracy of the proposed method have been verified through simulations and experiments. The calibration error can be reduced by about 20–80% compared with the commonly used cell calibration, especially for situations of long distance, poor visibility, or optically thick plumes. © 2020 Optical Society of America
  Accession Number: 20205109635301
• Record 524 of
  
  Title:Iterative local Fourier transform-based high-accuracy wavelength calibration for Fourier transform imaging spectrometer
  
  Author(s):Xu, Yixuan(1); Li, Jianxin(1,2); Bai, Caixun(3); Wei, Ming(1); Liu, Jie(1); Wang, Yubo(1); Ji, Yiqun(4,5)
  Source: Optics Express  Volume: 28  Issue: 4  DOI: 10.1364/OE.384058  Published: February 17, 2020  
  Abstract:An iterative local Fourier transform (ILFT)-based high-accuracy wavelength calibration for Fourier transform imaging spectrometer (FTIS) is proposed. The wavelength calibration for FTIS is to determine the relation between the wavelength and the wavenumber position. However, the wavenumber position solved by conventional method is only accurate up to integers restricted by the picket-fence effect of discrete Fourier transform. While the proposed ILFT can increase the accuracy of calculating the wavenumber position by combining the local Fourier transform and a few iterations. In this paper, the method is investigated in theory and then by simulations and experiments. The simulations show that the accuracy of the wavenumber position calculated by the ILFT is increased by 100 times than conventional method with noise, phase error, and non-uniform sampling of optical path difference. And the experimental results indicate that the ILFT decreases the absolute error of wavelength calibration from about 2.03 nm to 0.16 nm. Therefore, the method provides theoretical and technical support for FTIS and promotes the development of superior resolutions therein. © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
  Accession Number: 20200708178905
• Record 525 of
  
  Title:Experimental study on a high-sensitivity optical fiber sensor in wide-range refractive index detection
  
  Author(s):Meng, Xiaojian(1); Li, Jianshe(1,2,3); Guo, Ying(1); Liu, Yundong(1); Li, Shuguang(1); Guo, Haitao(2); Bi, Weihong(3); Lu, Huibin(3); Cheng, Tonglei(4)
  Source: Journal of the Optical Society of America B: Optical Physics  Volume: 37  Issue: 10  DOI: 10.1364/JOSAB.399424  Published: October 1, 2020  
  Abstract:A novel plasmonic sensor based on a photonic crystal fiber has been fabricated. Experimental results show that 2 cm is an optimal fiber length of the sensor for refractive index monitoring. It is found that the average wavelength sensitivity and the resolution of the proposed sensor are 4000 nm/RIU and 2.5 × 10−5 RIU in the wind range of 1.3333–1.4035, respectively. In addition, this paper presents a set of operation flat roofs that is used in the side-polished fiber technique. Moreover, two effective methods of coating silver film are discussed in detail. The research in this paper has enlightening significance for exploring new optical fiber sensing technology and will open a new design methodology for optical fiber sensors. © 2020 Optical Society of America
  Accession Number: 20204409430987
• Record 526 of
  
  Title:Optical frequency comb generation by hybrid mode-locking in a nested cavity scheme
  
  Author(s):Fischer, Bennet(1); Rahim, Aadhi A.(1); Rimoldi, Cristina(1); Roztocki, Piotr(1); Lauro, Luigi di(1); Chemnitz, Mario(1); Kovalev, Anton V.(2); Chu, Sai T.(3); Little, Brent E.(4); Moss, David J.(5); Viktorov, Evgeny A.(2); Kues, Michael(6); Morandotti, Roberto(1,2,7)
  Source: Optics InfoBase Conference Papers  Volume: Part F184-IPRSN 2020  Issue:   DOI: null  Published: 2020  
  Abstract:We present a hybrid fiber-integrated mode-locking scheme using a microring and active modulation. Nonlinear polarization rotation and phase modulation enable long-term frequency comb generation, and access to higher harmonic mode-locking. © 2020 The Author(s)
  Accession Number: 20204509464916
• Record 527 of
  
  Title:Athermal third harmonic generation in micro-ring resonators
  
  Author(s):Wang, Shao Hao(1,6); Li, Yu Hua(2,7); Little, Brent E.(3); Wang, Lei Ran(3,4); Wang, Xiang(5); Davidson, Roy R.(5); Chu, Sai Tak(2)
  Source: Opto-Electronic Advances  Volume: 3  Issue: 12  DOI: 10.29026/oea.2020.200028  Published: 2020  
  Abstract:Nonlinear high-harmonic generation in micro-resonators is a common technique used to extend the operating range of applications such as self-referencing systems and coherent communications in the visible region. However, the generated high-harmonic emissions are subject to a resonance shift with a change in temperature. We present a comprehensive study of the thermal behavior induced phase mismatch that shows this resonance shift can be compensated by a combination of the linear and nonlinear thermo-optics effects. Using this model, we predict and experimentally demonstrate visible third harmonic modes having temperature dependent wavelength shifts between -2.84 pm/°C and 2.35 pm/°C when pumped at the L-band. Besides providing a new way to achieve athermal operation, this also allows one to measure the thermal coefficients and Q-factor of the visible modes. Through steady state analysis, we have also identified the existence of stable athermal third harmonic generation and experimentally demonstrated orthogonally pumped visible third harmonic modes with a temperature dependent wavelength shift of 0.05 pm/°C over a temperature range of 12 °C. Our findings promise a configurable and active temperature dependent wavelength shift compensation scheme for highly efficient and precise visible emission generation for potential 2f-3f self-referencing in metrology, biological and chemical sensing applications. © 2019 Institute of Optics and Electronics, Chinese Academy of Sciences.
  Accession Number: 20212810637998
• Record 528 of
  
  Title:Distinct laser dynamics from a single figure-eight laser with an integrated nonlinear waveguide
  
  Author(s):Aadhi, A.(1); Roztocki, Piotr(1); Kovalev, Anton V.(2); Kues, Michael(3); Fischer, Bennet(1); Reimer, Christian(4); Zhang, Yanbing(1); Wang, Tao(1,5); Little, Brent E.(6); Chu, Sai T.(7); Wang, Zhiming(5); Moss, David J.(8); Viktorov, Evgeny A.(2); Morandotti, Roberto(1,5)
  Source: Optics InfoBase Conference Papers  Volume:   Issue:   DOI: null  Published: 2020  
  Abstract:We report a passive mode-locked laser system using a nonlinear amplifying loop mirror configuration with an integrated waveguide, capable of delivering different temporal pulse profiles with adjustable features from a single compact architecture. © 2020 The Author (s).
  Accession Number: 20212110389290