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https://www.readbyqxmd.com/read/28438009/modulation-format-free-and-automatic-bias-control-for-optical-iq-modulators-based-on-dither-correlation-detection
#1
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
https://www.readbyqxmd.com/read/28438006/measurements-and-modeling-of-multipath-interference-at-wavelengths-below-cable-cut-off-in-a-g-654-optical-fiber-span
#2
John D Downie, Jason Hurley, Hector DePedro, Steven Garner, Jeremy Blaker, Aramais Zakharian, Sergey Ten, Greg Mills
Transmission below the cable cut-off wavelength may be a concern in some systems, especially for an optical supervisory channel (OSC) operating below the signal transmission band in systems built with G.654 fiber. In this work, we constructed a cabled span of G.654-compliant fiber and measured the multipath interference (MPI) generated during propagation through the span at a range of wavelengths below the cable cut-offs of the constituent fibers. Measurements were made under a range of conditions including different splice losses and the presence or absence of higher order mode filters placed around the splices...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28438005/comparative-studies-on-the-quality-factors-of-whispering-gallery-modes-and-hybrid-plasmon-photon-modes
#3
Ping Gu, Jiawei Chen, Mingjie Wan, Zhuo Chen, Zhenlin Wang
We theoretically and experimentally investigate the multipolar hybrid plasmon-photon modes supported by a dielectric-metal core-shell resonator consisting of a dielectric core wrapped by a thin silver shell and the whispering-gallery modes in its pure dielectric counterpart (the dielectric sphere with the same size). We theoretically demonstrate that in a certain wavelength range the achievable maximum Q-factors of hybrid modes could be either larger or smaller than that of whispering-gallery modes, depending on the size of the resonator...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28438002/hot-luminescence-from-gold-nanoflowers-and-its-application-in-high-density-optical-data-storage
#4
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
https://www.readbyqxmd.com/read/28437997/effect-of-zno-nanostructures-on-the-optical-properties-of-white-light-emitting-diodes
#5
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
https://www.readbyqxmd.com/read/28437996/high-contrast-switchability-of-vo-sub-2-sub-based-metamaterial-absorbers-with-ito-ground-plane
#6
Jitendra K Pradhan, S Anantha Ramakrishna, Bharathi Rajeswaran, Arun M Umarji, Venu Gopal Achanta, Amit K Agarwal, Amitava Ghosh
A metamaterial consisting of an array of gold micro-disks, separated from a ground plane of indium tin oxide (ITO) by a thin film of vanadium dioxide (VO<sub>2</sub>), behaves as a perfect absorber at infrared (IR) frequencies at room temperature. This metamaterial, which is transparent to visible light, can be switched to a highly reflecting state for IR light by heating the metamaterial to temperatures larger than the metal-insulator phase transition temperature 68°C of VO<sub>2</sub>...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437994/high-speed-asynchronous-optical-sampling-based-on-ghz-yb-kyw-oscillators
#7
C Li, N Krauß, G Schäfer, L Ebner, O Kliebisch, J Schmidt, S Winnerl, M Hettich, T Dekorsy
A low-cost scheme of high-speed asynchronous optical sampling based on Yb:KYW oscillators is reported. Two GHz diode-pumped oscillators with a slight pulse repetition rate offset serve as pump and probe source, respectively. The temporal resolution of this system is limited to 500 fs mainly by the pulse duration of the oscillators and also by relative timing jitter between the oscillators. A near-shot-noise noise floor around 10<sup>-6</sup> (∆R/R) is obtained within a data acquisition time of a few seconds...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437993/integrated-optical-force-sensors-using-focusing-photonic-crystal-arrays
#8
Jingkun Guo, Richard A Norte, S Gröblacher
Mechanical oscillators are at the heart of many sensor applications. Recently several groups have developed oscillators that are probed optically, fabricated from high-stress silicon nitride films. They exhibit outstanding force sensitivities of a few aN/Hz<sup>1/2</sup> and can also be made highly reflective, for efficient detection. The optical read-out usually requires complex experimental setups, including positioning stages and bulky cavities, making them impractical for real applications. In this paper we propose a novel way of building fully integrated all-optical force sensors based on low-loss silicon nitride mechanical resonators with a photonic crystal reflector...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437992/a-large-airborne-survey-of-earth-s-visible-infrared-spectral-dimensionality
#9
David R Thompson, Joseph W Boardman, Michael L Eastwood, Robert O Green
The intrinsic spectral dimensionality indicates the observable degrees of freedom in Earth's solar-reflected light field, quantifying the diversity of spectral content accessible by visible and infrared remote sensing. The solar-reflected regime spans the 0.38 - 2.5 μm interval, and is captured by a wide range of current and planned instruments on both airborne and orbital platforms. To date there has been no systematic study of its spectral dimensionality as a function of space, time, and land cover. Here we report a multi-site, multi-year statistical survey by NASA's "Classic" Airborne Visible Near InfraRed Spectrometer (AVIRIS-C)...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437989/low-loss-compact-and-fabrication-tolerant-si-wire-90%C3%A2-waveguide-bend-using-clothoid-and-normal-curves-for-large-scale-photonic-integrated-circuits
#10
Takeshi Fujisawa, Shuntaro Makino, Takanori Sato, Kunimasa Saitoh
Ultimately low-loss 90° waveguide bend composed of clothoid and normal curves is proposed for dense optical interconnect photonic integrated circuits. By using clothoid curves at the input and output of 90° waveguide bend, straight and bent waveguides are smoothly connected without increasing the footprint. We found that there is an optimum ratio of clothoid curves in the bend and the bending loss can be significantly reduced compared with normal bend. 90% reduction of the bending loss for the bending radius of 4 μm is experimentally demonstrated with excellent agreement between theory and experiment...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437987/source-diversity-for-transport-of-intensity-phase-imaging
#11
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
https://www.readbyqxmd.com/read/28437984/light-bullets-in-coupled-nonlinear-schr%C3%A3-dinger-equations-with-variable-coefficients-and-a-trapping-potential
#12
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
https://www.readbyqxmd.com/read/28437981/efficient-laser-noise-reduction-method-via-actively-stabilized-optical-delay-line
#13
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
https://www.readbyqxmd.com/read/28437978/tunable-optical-cage-array-generated-by-dammann-vector-beam
#14
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
https://www.readbyqxmd.com/read/28437971/energy-efficient-on-chip-optical-diode-based-on-the-optomechanical-effect
#15
Huaqing Qiu, Jianji Dong, Li Liu, Xinliang Zhang
We propose and experimentally demonstrate an energy-efficient optical diode based on the optomechanical effect. The optical signals could transmit during forward propagation while be blocked during backward propagation. When launching optical signal with a low power of 4.0 mW, the maximum resonance red-shift of the asymmetric silicon microring resonator (MRR) could be up to 0.74 nm, in this case, a forward-backward nonreciprocal transmission ratio (NTR) of 12.7 dB has been achieved. The 10-dB and 5-dB operation bandwidths are 0...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437964/passively-coupled-low-coherence-interferometric-duct-profiling-with-an-astigmatism-corrected-conical-mirror
#16
Helen D Ford, Ralph P Tatam
Duct-profiling in test samples up to 25 mm in diameter has been demonstrated using a passive, low-coherence probe head with a depth resolution of 7.8 μm, incorporating an optical-fibre-linked conical mirror addressed by a custom-built array of single-mode fibres. Zemax modelling, and experimental assessment of instrument performance, show that degradation of focus, resulting from astigmatism introduced by the conical mirror, is mitigated by the introduction of a novel lens element. This enables a good beam focus to be achieved at distances of tens of millimetres from the cone axis, not achievable when the cone is used alone...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437962/rapidly-reconfigurable-high-fidelity-optical-arbitrary-waveform-generation-in-heterogeneous-photonic-integrated-circuits
#17
Shaoqi Feng, Chuan Qin, Kuanping Shang, Shibnath Pathak, Weicheng Lai, Binbin Guan, Matthew Clements, Tiehui Su, Guangyao Liu, Hongbo Lu, Ryan P Scott, S J Ben Yoo
This paper demonstrates rapidly reconfigurable, high-fidelity optical arbitrary waveform generation (OAWG) in a heterogeneous photonic integrated circuit (PIC). The heterogeneous PIC combines advantages of high-speed indium phosphide (InP) modulators and low-loss, high-contrast silicon nitride (Si<sub>3</sub>N<sub>4</sub>) arrayed waveguide gratings (AWGs) so that high-fidelity optical waveform syntheses with rapid waveform updates are possible. The generated optical waveforms spanned a 160 GHz spectral bandwidth starting from an optical frequency comb consisting of eight comb lines separated by 20 GHz channel spacing...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437960/wind-ranging-and-velocimetry-with-low-peak-power-and-long-duration-modulated-laser
#18
Eiichi Yoshikawa, Tomoo Ushio
A novel approach to simultaneous wind ranging and velocimetry using low peak power, long-duration modulated laser pulse transmissions is proposed. Received signals backscattered by aerosol particles are processed by a multi-reference matched-filter (MRMF) which performs matched filter processing between the received signal and several reference signals in parallel and outputs a range-velocity profile of received power. Ranging and velocimetry are performed simultaneously by estimating received power, radial velocity, and velocity dispersion from a velocity profile at an arbitrary range in the range-velocity profile...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437934/dual-channel-multilayer-coated-surface-plasmon-resonance-sensor-for-dual-refractive-index-range-measurements
#19
Mengdi Lu, Wei Peng, Qiang Liu, Yun Liu, Lixia Li, Yuzhang Liang, Jean-Francois Masson
We present a novel multilayer-coated surface plasmon resonance sensor for dual refractive index range measurements based on a capillary structure. The sensing elements include an internally coated Ag layer and an externally coated bilayer of Au with an overlayer of thin indium tin oxide (ITO). The internal Ag layer was sensitive to higher refractive index (RI) medium while the external Au/ITO layer was sensitive to lower refractive index medium. We evaluated the sensor performance by measuring RI changes in two channels, RI sensitivities were -1951 nm/RIU and 2496 nm/RIU, respectively...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437931/circular-core-single-mode-polymer-optical-waveguide-fabricated-using-the-mosquito-method-with-low-loss-at-1310-1550-nm
#20
Kazuki Yasuhara, Feng Yu, Takaaki Ishigure
We fabricate low-loss single-mode (SM) polymer optical waveguides using a photomask-free simple technique named the Mosquito method. The insertion losses of a 5-cm long SM polymer waveguide fabricated are 2.52 dB and 4.03 dB at 1310- and 1550-nm wavelengths, respectively. The coupling loss between a single-mode fiber and the waveguide is as low as 0.5 dB including the Fresnel reflection. The 0.5-dB misalignment tolerance in the radial direction is ± 2.0 μm at 1550 nm. The Mosquito method is promising for fabricating SM polymer optical waveguides compatible with silicon photonics chips...
April 17, 2017: Optics Express
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