2015

• Record 265 of
  
  Title:Study of Ti: sapphire double line waveguide written by femtosecond laser
  
  Author(s):Liu, Shuang(1,2); Liu, Xin(1,2); Tang, Wenlong(1,2); Cheng, Guanghua(1)
  Source: Zhongguo Jiguang/Chinese Journal of Lasers  Volume: 42  Issue: 2  DOI: 10.3788/CJL201542.0203001  Published: February 10, 2015  
  Abstract:Ti: sapphire crystal is one of the most important materials as a laser medium, due to its broad absorption band and widely tunable output band, therefore it has wide application in integrated optics. By femtosecond laser with repetition rate of 1 kHz, central wavelength of 800 nm and pulse width of 120 fs, double line waveguide in Ti:sapphire crystal is transversely written. The impacts of the processing conditions, i.e., inscribing depth, writing speed and the track distance on the waveguide formation are systematically studied, and the waveguide with better guiding mode is achieved when laser pulse energy is 2 μJ, inscribing depth is 175 μm, writing speed is 90 μm/s and the distance between two tacks is 26 μm. And the double line waveguide shows polarization dependent optical guiding. Based on the near-field mode intensity, the refractive index profile of the optical waveguide is reconstructed, and the max positive refractive index change is about 1.9×10-4. In addition, by using the scattering technique, the propagation loss of the waveguide is 1.82 dB/cm. ©, 2015, Science Press. All right reserved.
  Accession Number: 20151700790209
• Record 266 of
  
  Title:Streak tube with large work area and small size used in lidar detection system
  
  Author(s):Hui, Dandan(1,2); Tian, Jinshou(1); Lu, Yu(1); Wang, Junfeng(1)
  Source: Guangxue Xuebao/Acta Optica Sinica  Volume: 35  Issue: 12  DOI: 10.3788/AOS201535.1232001  Published: December 10, 2015  
  Abstract:A small-size streak tube with electrostatic focusing lens is designed with the aid of three-dimensional electromagnetic simulation software, CST. Distances between electrodes of the streak tube and their voltages are determined by orthogonal experiments. Also, according to the aberration theory of the streak tube, its imaging qualities are analyzed and evaluated systematically. The optimal streak tube possesses predominant performances. The diameter of work area of the photocathode is larger than 28 mm; physical temporal resolution is better than 30 ps; static spatial resolution at the margin of the photocathode is greater than 20 lp/mm; electron-optical magnification of the tube is 1.07; overall length of the streak tube is only 100 mm; outer diameter of streak tube is 50 mm. The designed streak tube with large work area and small size meets the requirements of scannerless lidar systems in the applications of military imaging scenarios, space exploration and marine detection. © 2015, Chinese Laser Prees. All right reserved.
  Accession Number: 20160401852579
• Record 267 of
  
  Title:F-state based permanent optical data storage in bacteriorhodopsin film
  
  Author(s):Yu, Xiang-Hua(1); Yao, Bao-Li(1); Li, Xin-Yu(2); Liu, Shi-Lei(2); Lei, Ming(1); Li, Run-Ze(1); Liang, Yan-Sheng(1); Zhou, Xing(1); Wu, Di(1); Dan, Dan(1); Min, Jun-Wei(1); Yan, Shao-Hui(1)
  Source: Wuli Xuebao/Acta Physica Sinica  Volume: 64  Issue: 2  DOI: 10.7498/aps.64.024218  Published: January 20, 2015  
  Abstract:Upon excitation of high intensity linearly polarized femtosecond laser, a blue-shifted two-photon induced photoproduct named F540 state with permanent photo-induced anisotropy is observed in bacteriorhodopsin (BR) films. Based on the F-state, permanent optical data storage can be realized with spatial field modulation of femtosecond laser. By using a phase-only spatial light modulator to modulate the spatial phase distribution of the incident femtosecond laser beam, we generate spot-patterns in the focal plane of the microscopic objective lens, and the patterns are recorded in the BR film. At the same time, by varying the polarization direction of the excitation laser beam, polarization-multiplexed optical data storage in the BR film is demonstrated, which is applicable to high-density optical data storage and optical information encryption. © 2015 Chinese Physical Society.
  Accession Number: 20150600488140
• Record 268 of
  
  Title:Autofocusing and resolution enhancement in digital holographic microscopy by using speckle-illumination
  
  Author(s):Zheng, Juanjuan(2); Pedrini, Giancarlo(1); Gao, Peng(1,2); Yao, Baoli(2); Osten, Wolfgang(1)
  Source: Journal of Optics (United Kingdom)  Volume: 17  Issue: 8  DOI: 10.1088/2040-8978/17/8/085301  Published: August 1, 2015  
  Abstract:Sequential speckle illumination has been incorporated into digital holographic microscopy (DHM) for autofocusing and resolution enhancement. For autofocusing, the image plane is numerically determined by searching for the minimal deviation among the reconstructed images obtained by different speckle illuminations and propagating the object wave to the image plane accordingly. Furthermore, an iterative method is used to synthesize the numerical aperture from the reconstructed object waves obtained by different speckle illuminations, in order to achieve resolution enhancement. The feasibility of the proposed method is demonstrated by both simulation and experiment. © 2015 IOP Publishing Ltd.
  Accession Number: 20153201156264
• Record 269 of
  
  Title:Large mode area waveguides by volume ultrafast laser photoinscription
  
  Author(s):Cheng, Guanghua(1); Liu, Xin(1); Stoian, Razvan(2)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 9449  Issue:   DOI: 10.1117/12.2083183  Published: 2015  
  Abstract:Multicore structures based on increased index waveguiding traces are fabricated by ultrafast laser photo inscription in bulk optical glass. A parametric study of the geometry of structure, number of traces and index contrast is discussed with respect to guided modes characteristics. Multicore waveguide present optical designs allowing large mode area light guiding by ultrafast laser photo inscription with coherent mode superposition in near infrared and mid-infrared in fused silica and Chalcogenide glass.. © 2015 SPIE.
  Accession Number: 20151100635486
• Record 270 of
  
  Title:Autofocusing and resolution enhancement in speckleilluminated digital holographic microscopy
  
  Author(s):Gao, Peng(1,2); Zheng, Juanjuan(1); Yao, Baoli(1); Pedrini, Giancarlo(2); Osten, Wolfgang(2)
  Source: Digital Holography and Three-Dimensional Imaging, DH 2015  Volume:   Issue:   DOI: 10.1364/dh.2015.dt3a.2  Published: May 18, 2015  
  Abstract:Sequential speckle illumination is incorporated into digital holographic microscopy (DHM) for autofocusing and resolution enhancement. The feasibility of the proposed method is demonstrated by microscopic phase imaging on a transparent sample.
  Accession Number: 20152701006712
• Record 271 of
  
  Title:Nanoslit-microcavity-based narrow band absorber for sensing applications
  
  Author(s):Lu, Xiaoyuan(1); Zhang, Lingxuan(1); Zhang, Tongyi(1)
  Source: Optics Express  Volume: 23  Issue: 16  DOI: 10.1364/OE.23.020715  Published: August 10, 2015  
  Abstract:We propose an ultranarrow bandwidth perfect infrared absorber consisting of a metal periodic structured surface with nanoslits, a spacer dielectric, and a metal back plate. Its bandwidth and aborption are respectively about 8 nm and 95%. The thickness of the nanobars and the spacer, and the width of the nanoslits are primary factors determining the absorption performance. This structure not only has narrow bandwidth but also can obtain the giant electric field enhancement in the tiny volume of the nanoslits. Operated as a refractive index sensor, this structure has figure of merit as high as 25. It has potential in biomedical and sensing applications. © 2015 Optical Society of America.
  Accession Number: 20160701924885
• Record 272 of
  
  Title:763 fs Passively mode-locked Yb:Y2SiO5 laser with a graphene oxide absorber mirror
  
  Author(s):Zhu, Hongtong(1); Cai, Wei(1); Wei, Jiafeng(1); Liu, Jie(1); Zheng, Lihe(2); Su, Liangbi(2); Xu, Jun(2); Wang, Yonggang(3)
  Source: Optics and Laser Technology  Volume: 68  Issue:   DOI: 10.1016/j.optlastec.2014.11.018  Published: May 2015  
  Abstract:Based on a graphene oxide absorber mirror, the laser-diode pumped mode-locked Yb:Y2SiO5 (Yb:YSO) laser was demonstrated for the first time. The laser generated pulses with pulse duration as short as ~763 fs and average output power of 700 mW at the central wavelength of 1059 nm. The corresponding peak power and energy of a single pulse were ~8.6 kW and ~7.4 nJ, respectively. To our best knowledge, this is the shortest bulk mode-locked laser based on graphene oxide. © 2014 Elsevier Ltd.
  Accession Number: 20145000311902
• Record 273 of
  
  Title:Metal-dielectric-metal based narrow band absorber for sensing applications
  
  Author(s):Lu, Xiaoyuan(1); Wan, Rengang(1); Zhang, Tongyi(1)
  Source: Optics Express  Volume: 23  Issue: 23  DOI: 10.1364/OE.23.029842  Published: November 16, 2015  
  Abstract:We have investigated numerically the narrowband absorption property of a metal-dielectric-metal based structure which includes a top metallic nanoring arrays, a metal backed plate, and a middle dielectric spacer. Its absorption is up to 90% with linewidth narrower than 10 nm. This can be explained in terms of surface lattice resonance of the periodic structure. The spectrum with the sharp absorption dip, i.e.The lattice resonance, strongly depends on the refractive index of media surrounding the nanorings. This feature can be explored to devise a refractive index sensor, of which the bulk sensitivity factor is one order larger than that based on gap resonance mode, while the surface sensitivity factor can be two times larger. The proposed narrowband absorber has potential in applications of plasmonic biosensors. © 2015 Optical Society of America.
  Accession Number: 20160501882733
• Record 274 of
  
  Title:Hybrid tilted fiber grating based refractive index and liquid level sensing system
  
  Author(s):Yan, Zhijun(1,2); Mou, Chengbo(1); Sun, Zhongyuan(1); Zhou, Kaimin(1); Wang, Hushan(2); Wang, Yishan(2); Zhao, Wei(2); Zhang, Lin(1)
  Source: Optics Communications  Volume: 351  Issue:   DOI: 10.1016/j.optcom.2015.04.038  Published: May 17, 2015  
  Abstract:We report a refractive index (RI) and liquid level sensing system based on a hybrid grating structure comprising of a 45° and an 81° tilted fiber gratings (TFGs) that have been inscribed into a single mode fiber in series. In this structure, the 45°-TFG is used as a polarizer to filter out the transverse electric (TE) component and enable the 81°-TFG operating at single polarization for RI and level sensing. The experiment results show a lower temperature cross-sensitivity, only about 7.33 pm/°C, and a higher RI sensitivity, being around 180 nm/RIU at RI=1.345 and 926 nm/RIU at RI=1.412 region, which are significantly improved in comparison with long period fiber gratings. The hybrid grating structure has also been applied as a liquid level sensor, showing 3.06 dB/mm linear peak ratio sensitivity. © 2015 Elsevier B.V. All rights reserved.
  Accession Number: 20152100866485
• Record 275 of
  
  Title:Y2O3: Eu3+, Tb3+ spherical particles based anti-reflection and wavelength conversion bi-functional films: Synthesis and application to solar cells
  
  Author(s):Miao, Hui(1,2); Ji, Ruonan(1); Hu, Xiaoyun(1,2); Han, Linzi(1); Hao, Yuanyuan(1); Sun, Qian(1); Zhang, Dekai(1,2); Fan, Jun(3); Bai, Jintao(1,2); Hou, Xun(1,2,4)
  Source: Journal of Alloys and Compounds  Volume: 629  Issue:   DOI: 10.1016/j.jallcom.2014.12.133  Published: April 25, 2015  
  Abstract:In this study, Eu3+ and Tb3+ co-doped Y2O3 particles were prepared via the simple, cost-effective urea homogeneous precipitation method without additives. The chosen particles were added in the SiO2 sols to get anti-reflection (AR) and wavelength conversion bi-functional films. Careful investigations were carried out to find the optimum preparation conditions and proper morphology. SEM images showed that the particle sizes reduced as metal ion/urea ratio decreased. Additionally, the extracted particles turned from sphere to lamellar type when the deionized water, which was used as solvent, reduced to a certain extent. The mechanisms of the morphology formation and diversification were proposed as well. The as prepared materials can convert UV region photos to visible photons between 460 nm and 640 nm, which just matched the spectral response of most solar cells. The spherical sample showed better luminescence performance than the one with lamellar morphology. In addition, the optical transmittance spectra indicated that the films adding spherical particles had better anti-reflective performance, and the best adding amount was 0.08 g. Finally, As a proof-of-concept application, the as prepared bi-functional films were used to test the standard monocrystalline silicon solar cell assembled with anti-reflection and wavelength conversion bi-functional films photoelectric conversion properties. As a result, the as prepared bi-functional films could effectively improve the photoelectric conversion efficiency by 0.23% compared to pure SiO2 AR coating film and 0.55% compared to glass. © 2015 Elsevier B.V. All rights reserved.
  Accession Number: 20150400445861
• Record 276 of
  
  Title:Relevance Preserving Projection and Ranking for Web Image Search Reranking
  
  Author(s):Ji, Zhong(1); Pang, Yanwei(1); Li, Xuelong(2)
  Source: IEEE Transactions on Image Processing  Volume: 24  Issue: 11  DOI: 10.1109/TIP.2015.2437198  Published: November 1, 2015  
  Abstract:An image search reranking (ISR) technique aims at refining text-based search results by mining images' visual content. Feature extraction and ranking function design are two key steps in ISR. Inspired by the idea of hypersphere in one-class classification, this paper proposes a feature extraction algorithm named hypersphere-based relevance preserving projection (HRPP) and a ranking function called hypersphere-based rank (H-Rank). Specifically, an HRPP is a spectral embedding algorithm to transform an original high-dimensional feature space into an intrinsically low-dimensional hypersphere space by preserving the manifold structure and a relevance relationship among the images. An H-Rank is a simple but effective ranking algorithm to sort the images by their distances to the hypersphere center. Moreover, to capture the user's intent with minimum human interaction, a reversed $k$-nearest neighbor (KNN) algorithm is proposed, which harvests enough pseudorelevant images by requiring that the user gives only one click on the initially searched images. The HRPP method with reversed KNN is named one-click-based HRPP (OC-HRPP). Finally, an OC-HRPP algorithm and the H-Rank algorithm form a new ISR method, H-reranking. Extensive experimental results on three large real-world data sets show that the proposed algorithms are effective. Moreover, the fact that only one relevant image is required to be labeled makes it has a strong practical significance. © 1992-2012 IEEE.
  Accession Number: 20153401182458