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Chiu-Yen Wang, Yu-Chen Hong, Zong-Jie Ko, Ya-Wen Su, Jin-Hua Huang
In this study, defect-free zinc blende GaAs nanowires on Si (111) by molecular beam epitaxy (MBE) growth are systematically studied through Au-assisted vapor-liquid-solid (VLS) method. The morphology, density, and crystal structure of GaAs nanowires were investigated as a function of substrate temperature, growth time, and As/Ga flux ratio during MBE growth, as well as the thickness, annealing time, and annealing temperature of Au film using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), cathodoluminescence (CL), and Raman spectroscopy...
December 2017: Nanoscale Research Letters
Xiaolei Li, Lei Deng, Xiaoman Chen, Mengfan Cheng, Songnian Fu, Ming Tang, Deming Liu
A novel automatic bias control (ABC) method for optical in-phase and quadrature (IQ) modulator is proposed and experimentally demonstrated. In the proposed method, two different low frequency sine wave dither signals are generated and added on to the I/Q bias signal respectively. Instead of power monitoring of the harmonics of the dither signal, dither-correlation detection is proposed and used to adjust the bias voltages of the optical IQ modulator. By this way, not only frequency spectral analysis isn't required but also the directional bias adjustment could be realized, resulting in the decrease of algorithm complexity and the growth of convergence rate of ABC algorithm...
April 17, 2017: Optics Express
Qingbin Fan, Daopeng Wang, Pengcheng Huo, Zijie Zhang, Yuzhang Liang, Ting Xu
Conventional method to generate autofocusing Airy (AFA) beam involves the optical Fourier transform (FT) system, which has a fairly long working distance due to the focal length of FT lens, presence of spatial light modulator (SLM) and auxiliary total reflection mirrors. Here, we propose an extremely compact design to generate high-efficiency AFA beam at visible frequency by using metasurface which is composed of a single layer array of amorphous titanium dioxide (TiO<sub>2</sub>) elliptical nanofins sitting on the fused-silica substrate...
April 17, 2017: Optics Express
Yunbao Zheng, Haiying Liu, Jin Xiang, Qiaofeng Dai, Min Ouyang, Shaolong Tie, Sheng Lan
Gold nanoflowers with feature sizes ranging from several tenths to several hundred nanometers were synthesized by using the one-pot method. They were formed by the self-organization of gold nanoparticles of several nanometers and exhibited broad extinction spectra in the near infrared spectral range. Randomly distributed hot spots originating from the strongly localized modes were generated in gold nanoflowers and their appearances exhibited strong dependences on both the polarization and wavelength of the excitation light...
April 17, 2017: Optics Express
Yeonghyeon Gim, Dong Ho Shin, Do Yoon Moh, Han Seo Ko
For an electrohydrodynamic (EHD) jet, variables such as the direction of the meniscus and the ejection stability need to be analyzed. Thus, the EHD jet should be observed three-dimensionally (3D) because the variables can only be obtained in the 3D field, especially in unstable modes. However, if the 3D field is reconstructed from multi-directional binary images, eliminating reconstruction errors caused by invisible areas is almost impossible, even when using a tomographic technique. To solve this problem, a new 3D reconstruction method including an ellipse estimation was developed in this study...
April 17, 2017: Optics Express
Xiaoqi Zhu, Feiya Chen, Huanfa Peng, Zhangyuan Chen
We propose and demonstrate a novel optical frequency comb (OFC) based microwave photonic filter which is able to realize arbitrary filtering shape with linear phase response. The shape of filter response is software programmable using finite impulse response (FIR) filter design method. By shaping the OFC spectrum using a programmable waveshaper, we can realize designed amplitude of FIR taps. Positive and negative sign of FIR taps are achieved by balanced photo-detection. The double sideband (DSB) modulation and symmetric distribution of filter taps are used to maintain the linear phase condition...
April 17, 2017: Optics Express
Longshi Rao, Yong Tang, ZongTao Li, Xinrui Ding, Jiasheng Li, Shudong Yu, Caiman Yan, Hangaung Lu
White light produced by blue LEDs with yellow phosphor is the most widely used methods, but it results in poor quality in angular CCT uniformity. In this work, a novel technique was introduced to solve this problem by integrating different ZnO nanostructures into white light-emitting diodes. The experiment of ZnO doped films and the simulation of Finite-Difference Time-Domain (FDTD) were carried out. The result indicated scattering effect of ZnO nanoparticles could improve uniformity of scattering energy effectively...
April 17, 2017: Optics Express
Huijie Zhao, Xiaochun Diao, Hongzhi Jiang, Xudong Li
Recent advancements in 3D measurement technologies have increased the urgency of requiring high-speed 3D measurement in many fields. This study presents a novel four-step triangular pattern phase-shifting 3D measurement using the motion blur method, which combines the advantages of phase-shifting methods. To comply with the high speed requirement, binary coded triangular patterns are projected and could dither vertically. Therefore, the image captured by the camera is blurred into grayscale-intensity triangular patterns, which can be used for phase unwrapping and 3D reconstruction...
April 17, 2017: Optics Express
Defen Guo, Tao Chu
We propose and experimentally demonstrate broadband silicon mode (de)multiplexers based on the optimization of system adiabaticity using shortcuts to adiabaticity (STA). The measured insertion losses and crosstalks were less than 1.1 dB and -24 dB, respectively, for the five two-mode mode-division-multiplexing (MDM) links over wavelengths ranging from 1500 nm to 1600 nm. The four-mode MDM link showed measured insertion losses and crosstalks less than 1.3 dB and -23 dB, respectively, within the same wavelength range...
April 17, 2017: Optics Express
Tonmoy Chakraborty, Jonathan C Petruccelli
The transport of intensity equation (TIE) is a phase retrieval method that relies on measurements of the intensity of a paraxial field under propagation between two or more closely spaced planes. A limitation of TIE is its susceptibility to low frequency noise artifacts in the reconstructed phase. Under Köhler illumination, when both illumination power and exposure time are limited, the use of larger sources can improve low-frequency performance although it introduces blurring. Appropriately combining intensity measurements taken with a diversity of source sizes can improve both low- and high-frequency performance in phase reconstruction...
April 17, 2017: Optics Express
Seojun Lee, Hyungchae Kim, Jongcheon Lee, Changsoon Kim
We investigate scattering of surface plasmon polaritons (SPPs) at a planar metal-dielectric interface by a dielectric nanocube embedded in the metal layer using finite element method-based simulations. The scattering characteristics of the embedded nanocube, such as the scattering and absorption cross sections, far-field scattering patterns, reflectance, and transmittance, are calculated as functions of the wavelength of the incident SPP waves in the visible range. The main features of the characteristics are explained in connection with the excitation of plasmonic eigenmodes of the embedded nanocube...
April 17, 2017: Optics Express
Si-Liu Xu, Guo-Peng Zhao, Milivoj R Belić, Jun-Rong He, Li Xue
We analyze three-dimensional (3D) vector solitary waves in a system of coupled nonlinear Schrödinger equations with spatially modulated diffraction and nonlinearity, under action of a composite self-consistent trapping potential. Exact vector solitary waves, or light bullets (LBs), are found using the self-similarity method. The stability of vortex 3D LB pairs is examined by direct numerical simulations; the results show that only low-order vortex soliton pairs with the mode parameter values n ≤ 1, l ≤ 1 and m = 0 can be supported by the spatially modulated interaction in the composite trap...
April 17, 2017: Optics Express
P W M Tsang, Y T Chow, T-C Poon
A fast and non-iterative method for generating a phase-only hologram, hereafter referred to as the patterned-phase-only hologram (PPOH), is reported in this paper. Briefly, a phase mask with a periodic phase pattern is added to the source image, and converted into a hologram. Subsequently, only the phase component is retained as a phase-only hologram. Experimental evaluation reveals that the visual quality of the reconstructed images of the PPOH generated with our proposed method is favorable, and superior to that obtained with existing methods...
April 17, 2017: Optics Express
Dawei Li, Cheng Qian, Ye Li, Jianye Zhao
We report a fiber laser noise reduction method by locking it to an actively stabilized optical delay line, specifically a fiber-based Mach-Zehnder interferometer with a 10 km optical fiber spool. The fiber spool is used to achieve large arm imbalance. The heterodyne signal of the two arms converts the laser noise from the optical domain to several megahertz, and it is used in laser noise reduction by a phase-locked loop. An additional phase-locked loop is induced in the system to compensate the phase noise due to environmentally induced length fluctuations of the optical fiber spool...
April 17, 2017: Optics Express
F Mariani, F de León-Pérez, K J A Vendel, L Martín-Moreno, M P Van Exter
We present the first angle resolved measurements of extraordinary optical transmission (EOT) through hole array gratings in a gold film. Varying the lattice spacing of the arrays and looking at higher diffraction orders, we retrieve the angular emission pattern of the constituent holes with better signal to noise ratio than with single-hole experiments. We present a method to determine separately the angular dependence of the direct and resonant contribution to EOT by using the spectral features of the diffraction orders together with an established model...
April 17, 2017: Optics Express
Xiaoyu Weng, Luping Du, Peng Shi, Xiaocong Yuan
Optical cages attract considerable attentions recently owing to their potential applications in optical trapping, optical imaging and optical cloaking. However, the generation of tunable optical cage arrays in the transverse plane comes to a great challenge, which restricts the effectiveness of the above applications. In this work, we propose a full polarization-controlled method that optical cage arrays with tunable number and positions in the x-y plane can be generated by a so-called Dammann vector beam (DVB), both under the conditions of high- and low-NA focusing system...
April 17, 2017: Optics Express
Yuan-Yuan Zhao, Zhibo Hou, Guo-Yong Xiang, Yong-Jian Han, Chuan-Feng Li, Guang-Can Guo
Quantum state tomography is a key technology for fully determining a quantum state. Unfortunately, standard quantum state tomography is intractable for general many-body quantum states, because the number of measurements and the post-processing time increase exponentially with the size of the system. However, for the matrix product states (MPSs), there exists an efficient method using linearly scaled local measurements and polynomially scaled post-processing times. In this study, we demonstrate the validity of the method in practice by reconstructing a four-photon MPS from its local two- or three-photon reduced-density matrices with the presence of statistical errors and systematical errors in experiment...
April 17, 2017: Optics Express
Jian Chen, Chenhao Wan, Lingjiang Kong, Qiwen Zhan
We demonstrate a method to generate complex optical fields at the pupil plane of a high numerical aperture (NA) objective lens for the creation of diffraction limited optical focus with purely transverse spin angular momentum. The complex optical fields are analytically deduced through reversing the radiated patterns from two electric dipoles, which are located at the focal point of the high NA lens and oscillate respectively in x- and z- directions with phase difference of π/2. The derived fields can be experimentally created with a vectorial optical field generator...
April 17, 2017: Optics Express
Shih-Wen Chen, Jia-Han Li
Investigated in this paper is the interaction of light and the nanospheres composed by a dielectric core with a gold-shell cladding that causes the optical vortices inside the core and the whirlpools around the shell. Different radius ratios, dimensions and the dielectric functions of nanospheres were studied using the finite-difference time-domain method. It was found that optical vortices were most likely to occur in the regions of increased absorption cross section and reduced scattering cross section. Two optical vortices of the opposite polarity, each centered in one of the particles of a dimer are created by a nanoshell dimer...
April 17, 2017: Optics Express
Honghao Yu, Jun Chang, Xin Liu, Chuhan Wu, Yifan He, Yongjian Zhang
Herein, we propose a new security enhancing method that employs wavefront aberrations as optical keys to improve the resistance capabilities of conventional double-random phase encoding (DRPE) optical cryptosystems. This study has two main innovations. First, we exploit a special beam-expander afocal-reflecting to produce different types of aberrations, and the wavefront distortion can be altered by changing the shape of the afocal-reflecting system using a deformable mirror. Then, we reconstruct the wavefront aberrations via the surface fitting of Zernike polynomials and use the reconstructed aberrations as novel asymmetric vector keys...
April 17, 2017: Optics Express
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