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Optics Express

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https://www.readbyqxmd.com/read/29221107/interferometric-synthetic-aperture-microscopy-for-extended-focus-optical-coherence-microscopy
#1
Séverine Coquoz, Arno Bouwens, Paul J Marchand, Jérôme Extermann, Theo Lasser
Optical coherence microscopy (OCM) is an interferometric technique providing 3D images of biological samples with micrometric resolution and penetration depth of several hundreds of micrometers. OCM differs from optical coherence tomography (OCT) in that it uses a high numerical aperture (NA) objective to achieve high lateral resolution. However, the high NA also reduces the depth-of-field (DOF), scaling with 1/NA2. Interferometric synthetic aperture microscopy (ISAM) is a computed imaging technique providing a solution to this trade-off between resolution and DOF...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221106/high-sensitivity-optical-biosensor-based-on-polymer-materials-and-using-the-vernier-effect
#2
Paul Azuelos, Pauline Girault, Nathalie Lorrain, Luiz Poffo, Mohammed Guendouz, Monique Thual, Jonathan Lemaître, Parastesh Pirasteh, Isabelle Hardy, Joël Charrier
We demonstrate the fabrication of a Vernier effect SU8/PMATRIFE polymer optical biosensor with high homogeneous sensitivity using a standard photolithography process. The sensor is based on one micro-resonator embedded on each arm of a Mach-Zehnder interferometer. Measurements are based on the refractive index variation of the optical waveguide superstrate with different concentrations of glucose solutions. The sensitivity of the sensor has been measured as 17558 nm/RIU and the limit of detection has been estimated to 1...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221105/examination-of-potassium-diode-pumped-alkali-laser-using-he-ar-ch4-and-c2h6-as-buffer-gas
#3
Boris V Zhdanov, Matthew D Rotondaro, Michael K Shaffer, Randall J Knize
We examined the performance of a potassium diode pumped alkali laser (K DPAL) using He, Ar, CH4, C2H6 and a mixture of He and CH4 as a buffer gas to provide spin-orbit mixing of the 4P3/2 and 4P1/2 states of Potassium atoms. We found that pure helium cannot be used as an efficient buffer gas for continuous wave lasing without using a flowing system with a considerable flow speed of about 100 m/s. In contrast, using a small amount of methane (10-20 Torr) mixed with helium, continuous wave lasing can be achieved using very moderate flow speeds of about 1 m/s...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221104/accurate-measurements-of-circular-and-residual-linear-birefringences-of-spun-fibers-using-binary-polarization-rotators
#4
Zhexi Xu, X Steve Yao, Zhenyang Ding, X James Chen, Xin Zhao, Hao Xiao, Ting Feng, Tiegen Liu
We present a method to accurately measure the birefringence properties of spun fibers using binary polarization rotators. By taking the advantages of binary polarization rotator in polarization analysis, we are able to simultaneously measure both the circular and linear birefringences in a spun fiber with high accuracy. We obtain the circular and the residual linear birefringences of the spun fiber as a function of temperature T to be 3.34 × 10-5-5.11 × 10-8T and 8.1 × 10-6-1.19 × 10-8T, respectively, with the residual linear birefringence about 4 times less than the circular birefringence...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221103/compensation-of-aberration-in-quantitative-phase-imaging-using-lateral-shifting-and-spiral-phase-integration
#5
Inhyeok Choi, KyeoReh Lee, YongKeun Park
We present a simple and effective method to eliminate system aberrations in quantitative phase imaging. Using spiral phase integration, complete information about system aberration is calculated from three laterally shifted phase images. The present method is especially useful when measuring confluent samples in which acquisition of background area is challenging. To demonstrate validity and applicability, we present measurements of various types of samples including microspheres, HeLa cells, and mouse brain tissue...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221102/liquid-crystal-tunable-color-filters-based-on-aluminum-metasurfaces
#6
Zu-Wen Xie, Jhen-Hong Yang, Vishal Vashistha, Wei Lee, Kuo-Ping Chen
Designing color pixels using plasmonic nanostructures and metasurfaces has become a luring area of research in recent years. Here, we experimentally demonstrated the voltage tunability of a dynamic plasmonic color filter by using an aluminum grating integrated with the nematic liquid crystal (LC). Along with a typical substrate coated with rubbed polyimide film, the aluminum grating itself serves as a molecular alignment layer to form a twisted LC cell. This hybrid structure allows electrically controlled transmission color by applying the voltage...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221101/enhanced-light-matter-interactions-in-graphene-covered-dielectric-magnetic-mirrors
#7
Yiping Liu, Yunyun Dai, Qianchi Feng, Yuwei Shan, Lei Du, Yuyu Xia, Guang Lu, Fen Liu, Guiqiang Du, Chuanshan Tian, Shiwei Wu, Lei Shi, Jian Zi
Enhanced interactions of light with graphene on the surface of a lossless dielectric magnetic mirror (DMM) are studied theoretically and experimentally in the visible range, where the DMM is composed of truncated dielectric photonic crystals (PCs). The absorption of graphene on the DMM was enhanced by about 4-fold for the spectral range within the forbidden gap of PCs over a wide range of incidence angles for both transverse electric and transverse magnetic polarizations compared with that of free-standing graphene...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221100/automated-detection-of-cloud-and-aerosol-features-with-sacol-micro-pulse-lidar-in-northwest-china
#8
Hailing Xie, Tian Zhou, Qiang Fu, Jianping Huang, Zhongwei Huang, Jianrong Bi, Jinsen Shi, Beidou Zhang, Jinming Ge
The detection of cloud and aerosols using a modified retrieval algorithm solely for a ground-based micropulse lidar (MPL) is presented, based on one-year data at the Semi-Arid Climate Observatory and Laboratory (SACOL) site (35.57°N, 104.08°E, 1965.8 m), northwest of China, from March 2011 to February 2012. The work not only identifies atmosphere particle layers by means of the range-dependent thresholds based on elastic scattering ratio and depolarization ratio, but also discriminates the detected layers by combining empirical thresholds of the atmosphere's thermodynamics states and scattering properties and continuous wavelet transform (CWT) analyses...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221099/design-of-a-uniform-illumination-binocular-waveguide-display-with-diffraction-gratings-and-freeform-optics
#9
Zeyang Liu, Yajun Pang, Cheng Pan, Zhanhua Huang
Uniform illuminance over the expanded exit pupil is an important requirement for waveguide display systems with a wide field of view (FOV). To address this issue, we develop a monochromatic binocular waveguide display in this paper. Two surface-relief diffraction gratings are designed as in-couplers and out-couplers. The parameters of the gratings are optimized to achieve uniform diffraction efficiency distributions over a broad angular range. The grating couplers enable the system to realize a diagonal FOV of 40°...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221098/pulse-dynamics-of-dual-wavelength-dissipative-soliton-resonances-and-domain-wall-solitons-in-a-tm-fiber-laser-with-fiber-based-lyot-filter
#10
Pan Wang, Kangjun Zhao, Xiaosheng Xiao, Changxi Yang
We report on the first demonstration of dual-wavelength square-wave pulses in a thulium-doped fiber laser. Under appropriate cavity parameters, dual-wavelength dissipative soliton resonances (DSRs) and domain wall solitons (DWSs) are successively obtained. Meanwhile, dark pulses generation is achieved at the dual-wavelength DWSs region due to the overlap of the two domain wall pulses. The fiber-based Lyot filter, conducted by inserting PMF between an in-line PBS and a PD-ISO, facilitates the generation of dual-wavelength operation...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221097/high-wall-plug-efficiency-blue-iii-nitride-leds-designed-for-low-current-density-operation
#11
Leah Y Kuritzky, Andrew C Espenlaub, Benjamin P Yonkee, Christopher D Pynn, Steven P DenBaars, Shuji Nakamura, Claude Weisbuch, James S Speck
Commercial LEDs for solid-state lighting are often designed for operation at current densities in the droop regime (~35 A/cm2) to minimize costly chip area; however, many benefits can be realized by operating at low current density (J ≈1 - 5 A/cm2). Along with mitigation of droop losses and reduction of the operating voltage, low J operation of LEDs opens the design space for high light extraction efficiency (LEE). This work presents detailed ray tracing simulations of an LED design for low J operation with LEE ≈94%...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221096/high-resolution-beam-profiling-of-x-ray-free-electron-laser-radiation-by-polymer-imprint-development
#12
Benedikt Rösner, Florian Döring, Primož R Ribič, David Gauthier, Emiliano Principi, Claudio Masciovecchio, Marco Zangrando, Joan Vila-Comamala, Giovanni De Ninno, Christian David
High resolution metrology of beam profiles is presently a major challenge at X-ray free electron lasers. We demonstrate a characterization method based on beam imprints in poly (methyl methacrylate). By immersing the imprints formed at 47.8 eV into organic solvents, the regions exposed to the beam are removed similar to resist development in grayscale lithography. This allows for extending the sensitivity of the method by more than an order of magnitude compared to the established analysis of imprints created solely by ablation...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221095/optimizing-the-performance-of-non-collinear-optical-parametric-chirped-pulse-amplification-via-multi-pass-structure-based-on-two-geometry-configurations
#13
Wenqi Li, Chun Peng, Lu Xu, Lianghong Yu, Xiaoyan Liang
We propose a method for multi-pass non-collinear optical parametric chirped pulse amplification (MNOPCPA) based on two geometries, tangent phase-matching (TPM) and Poynting vector walk-off compensation (PVWC), which optimize the performance of optical parametric chirped pulse amplification (OPCPA). A feasible design scheme is also presented for use in implementing this approach. Employing this design, we construct and perform a numerical simulation, showing that back-conversion from the signal and idler to the pump can be inhibited, and that the conversion efficiency can be boosted dramatically, approaching the theoretical limit of ~64%, when amplification is nearly saturated at full bandwidth...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221094/direct-evidence-of-recombination-between-electrons-in-ingan-quantum-discs-and-holes-in-p-type-gan
#14
Xiaoxiao Sun, Xinqiang Wang, Ping Wang, Tao Wang, Bowen Sheng, Xiantong Zheng, Mo Li, Jian Zhang, Xuelin Yang, Fujun Xu, Weikun Ge, Bo Shen
Intense emission from an InGaN quantum disc (QDisc) embedded in a GaN nanowire p-n junction is directly resolved by performing cathodoluminescence spectroscopy. The luminescence observed from the p-type GaN region is exclusively dominated by the emission at 380 nm, which has been usually reported as the emission from Mg induced impurity bands. Here, we confirm that the robust emission from 380 nm is actually not due to the Mg induced impurity bands, but rather due to being the recombination between electrons in the QDisc and holes in the p-type GaN...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221093/low-loss-demonstration-and-refined-characterization-of-silicon-arrayed-waveguide-gratings-in-the-near-infrared
#15
Eric J Stanton, Nicolas Volet, John E Bowers
A resonator is characterized with two cascaded arrayed waveguide gratings (AWGs) in a ring formation. From this structure, the on-chip transmittance of a single AWG is extracted, independent of coupling efficiency. It provides improved measurement accuracy, which is essential for developing AWGs with extremely low loss. Previous methods normalize the off-chip AWG transmittance to that of a reference waveguide with identical coupling, leading to an uncertainty of ∼14 % on the extracted on-chip AWG transmittance...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221092/structured-light-illumination-for-order-sorting-in-echelle-spectrometers
#16
Ó Martínez-Matos, P Vaveliuk, C Rickenstorff
We report on the operation of an echelle spectrometer under structured light illumination. Each diffraction order of the spectrometer is encoded with a certain periodic structure allowing for order sorting by numerical analysis after detection. In contrast to cross-dispersed echelle spectrometers, in this approach the orders overlap at the detection plane so that the spectral calibration can be performed easily with a single reference wavelength. This operational simplification makes it possible to measure simultaneously the light source under study and the calibration wavelength giving rise to a self-calibrated echelle spectrometer...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221091/raman-lidar-for-hydrogen-gas-concentration-monitoring-and-future-radioactive-waste-management
#17
Anasthase Liméry, Nicolas Cézard, Didier Fleury, Didier Goular, Christophe Planchat, Johan Bertrand, Alain Hauchecorne
A multi-channel Raman lidar has been developed, allowing for the first time simultaneous and high-resolution profiling of hydrogen gas and water vapor. The lidar measures vibrational Raman scattering in the UV (355 nm) domain. It works in a high-bandwidth photon counting regime using fast SiPM detectors and takes into account the spectral overlap between hydrogen and water vapor Raman spectra. Measurement of concentration profiles of H2 and H2O are demonstrated along a 5-meter-long open gas cell with 1-meter resolution at 85 meters...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221090/study-of-the-momentum-resolved-plasmonic-field-energy-of-bloch-like-surface-plasmon-polaritons-from-periodic-nanohole-array
#18
Z L Cao, H C Ong
The angular surface plasmon mediated fluorescence from a two-dimensional Au nanohole array has been studied by reflectivity spectroscopy and Fourier-space photoluminescence microscopy. By using the rate equation model and temporal coupled mode theory, we determine the momentum-dependent coupling rate of light emitters to (-1,0) Bloch-like surface plasmon polaritons (SPPs) in the first Brillouin zone. The rate increases gradually when the SPPs propagate away from the Γ-X direction and split into two at the Γ-M point where two coupled modes are formed...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221089/determination-of-complex-hermitian-and-anti-hermitian-interaction-constants-from-a-coupled-photonic-system-via-coherent-control
#19
Z L Cao, H C Ong
By manipulating the relative amplitude and phase between two incoming lights, coherent control of photonic systems can be realized. Here, we show by temporal coupled mode theory and finite-difference time-domain simulation that a coupled system can be actively controlled to exhibit plenty of different spectral, angular, and excitation behaviors. Electromagnetically induced transparency-like and Fano spectral characteristics as well as strong beam steering have been observed. Remarkably, by selectively exciting the coupled modes, we have developed a new approach to determine the complex Hermitian and anti-Hermitian interaction constants...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29221088/tunable-terahertz-transmission-properties-of-aligned-ni-nanowire-arrays
#20
Wenfeng Xiang, Yi Liu, Minghao Hu, Haizhong Guo
Aligned Ni nanowire (NW) arrays were investigated for terahertz (THz) wave modulation. By adjusting the NW density and order of the NW arrays, the resonant frequency and intensity of the THz waves can be effectively tuned. The tuning range of the resonant frequency is about 0.29 THz, and a transmittance of less than 40% in the frequency region from 0.5 to 2 THz is achieved by changing the NW density. Although the order of the NW arrays has no influence on the resonant frequency, the transmittance can be tuned about 21%...
November 27, 2017: Optics Express
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