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https://www.readbyqxmd.com/read/27910644/development-of-plasma-bolometers-using-fiber-optic-temperature-sensors
#1
M L Reinke, M Han, G Liu, G G van Eden, R Evenblij, M Haverdings, B C Stratton
Measurements of radiated power in magnetically confined plasmas are important for exhaust studies in present experiments and expected to be a critical diagnostic for future fusion reactors. Resistive bolometer sensors have long been utilized in tokamaks and helical devices but suffer from electromagnetic interference (EMI). Results are shown from initial testing of a new bolometer concept based on fiber-optic temperature sensor technology. A small, 80 μm diameter, 200 μm long silicon pillar attached to the end of a single mode fiber-optic cable acts as a Fabry-Pérot cavity when broadband light, λo ∼ 1550 nm, is transmitted along the fiber...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27906342/responsivity-optimization-of-a-high-speed-germanium-on-silicon-photodetector
#2
Monireh Moayedi Pour Fard, Glenn Cowan, Odile Liboiron-Ladouceur
This paper experimentally demonstrates a design optimization of an evanescently-coupled waveguide germanium-on-silicon photodetector (PD) towards high-speed (> 30 Gb/s) applications. The resulting PD provides a responsivity of 1.09 A/W at 1550 nm, a dark current of 3.5 µA and bandwidth of 42.5 GHz at 2 V reverse-bias voltage. To optimize the PD, the impact of various design parameters on performance is investigated. A novel optimization methodology for the PD's responsivity based on the required bandwidth is developed...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27877891/bloch-surface-wave-structures-for-high-sensitivity-detection-and-compact-waveguiding
#3
Muhammad Umar Khan, Brian Corbett
Resonant propagating waves created on the surface of a dielectric multilayer stack, called Bloch surface waves (BSW), can be designed for high sensitivity monitoring of the adjacent refractive index as an alternative platform to the metal-based surface plasmon resonance (SPR) sensing. The resonant wavelength and polarization can be designed by engineering of the dielectric layers unlike the fixed resonance of SPR, while the wide bandwidth low loss of dielectrics permits sharper resonances, longer propagation lengths and thus their use in waveguiding devices...
2016: Science and Technology of Advanced Materials
https://www.readbyqxmd.com/read/27869860/quantitative-phase-microscopy-of-nanosecond-laser-induced-micro-modifications-inside-silicon
#4
Q Li, M Chambonneau, M Chanal, D Grojo
Laser-induced permanent modification inside silicon has been recently demonstrated by using tightly focused nanosecond sources at a 1550 nm wavelength. We have developed a quantitative-phase microscope operating in the near-infrared domain to characterize the laser-induced modifications deep into silicon. By varying the number of applied laser pulses and the energy, we observe porous and densified regions in the focal region. The observed changes are associated with refractive index variations |Δn| exceeding 10<sup>-3</sup>, enough to envision the laser writing of optical functionalities inside silicon...
November 20, 2016: Applied Optics
https://www.readbyqxmd.com/read/27857397/record-power-ultra-broadband-supercontinuum-source-based-on-highly-geo-sub-2-sub-doped-silica-fiber
#5
D Jain, R Sidharthan, P M Moselund, S Yoo, D Ho, O Bang
We demonstrate highly germania doped fibers for mid-infrared supercontinuum generation. Experiments ensure a highest output power of 1.44 W for a broadest spectrum from 700 nm to 3200 nm and 6.4 W for 800 nm to 2700 nm from these fibers, while being pumped by a broadband Erbium-Ytterbium doped fiber based master oscillator power amplifier. The effect of repetition frequency of pump source and length of germania-doped fiber has also been investigated. Further, germania doped fiber has been pumped by conventional supercontinuum source based on silica photonic crystal fiber supercontinuum source...
November 14, 2016: Optics Express
https://www.readbyqxmd.com/read/27857382/supercontinuum-seeded-few-cycle-mid-infrared-opcpa-system
#6
Philippe Rigaud, Aymeric Van de Walle, Marc Hanna, Nicolas Forget, Florent Guichard, Yoann Zaouter, Khmaies Guesmi, Frédéric Druon, Patrick Georges
We propose and demonstrate an OPCPA architecture emitting few-cycle pulses at 3070 nm and 1550 nm based on a high-energy femtosecond ytterbium-doped fiber amplifier pump. The short pump pulse duration allows direct seeding by a supercontinuum in the 1.4 - 1.7 µm signal range, generated in bulk YAG. It also allows a simplified dispersion management along the system and broad optical gain bandwidth. The dual output system delivers 20 µJ, 49 fs signal pulses at 1550 nm and 10 µJ, 72 fs idler pulses at 3070 nm...
November 14, 2016: Optics Express
https://www.readbyqxmd.com/read/27857280/micro-optoelectromechanical-systems-accelerometer-based-on-intensity-modulation-using-a-one-dimensional-photonic-crystal
#7
Arash Sheikhaleh, Kambiz Abedi, Kian Jafari, Reza Gholamzadeh
In this paper, we propose what we believe is a novel sensitive micro-optoelectromechanical systems (MOEMS) accelerometer based on intensity modulation by using a one-dimensional photonic crystal. The optical sensing system of the proposed structure includes an air-dielectric multilayer photonic bandgap material, a laser diode (LD) light source, a typical photodiode (1550 nm) and a set of integrated optical waveguides. The proposed sensor provides several advantages, such as a relatively wide measurement range, good linearity in the whole measurement range, integration capability, negligible cross-axis sensitivity, high reliability, and low air-damping coefficient, which results in a wider frequency bandwidth for a fixed resonance frequency...
November 10, 2016: Applied Optics
https://www.readbyqxmd.com/read/27828486/green-up-conversion-and-near-infrared-luminescence-of-femtosecond-laser-written-waveguides-in-er-sup-3-sup-mgo-co-doped-nearly-stoichiometric-linbo-sub-3-sub-crystal
#8
Jinman Lv, Xiaotao Hao, Feng Chen
We report on the green up-conversion and near-infrared (NIR) emission in Er<sup>3+</sup>, MgO co-doped nearly stoichiometric LiNbO<sub>3</sub> waveguides fabricated by femtosecond laser writing. The waveguides with so-called Type I geometry by laser writing support nearly single-mode propagation of light at NIR wavelength of 1.55 μm. In addition, it has been found that the guidance is only along the vertical (i.e., TM) polarization, which is due to the laser-induced positive changes of extraordinary index in the guiding core...
October 31, 2016: Optics Express
https://www.readbyqxmd.com/read/27828432/all-optical-sampling-and-magnification-based-on-xpm-induced-focusing
#9
J Nuño, M Gilles, M Guasoni, C Finot, J Fatome
We theoretically and experimentally investigate the design of an all-optical magnification and sampling function free from any active gain medium or additional amplified spontaneous noise emission. The proposed technique is based on the co-propagation of an arbitrary shaped signal together with an orthogonally polarized intense fast sinusoidal beating within a normally dispersive optical fiber. This process allows us to experimentally demonstrate a 40-GHz sampling operation as well as an 8-dB magnification of an arbitrary shaped nanosecond signal around 1550 nm in a 5-km long optical fiber...
October 31, 2016: Optics Express
https://www.readbyqxmd.com/read/27828394/greater-than-50-inversion-in-erbium-doped-chalcogenide-waveguides
#10
Kunlun Yan, Khu Vu, Rongping Wang, Steve Madden
We report Er-doped Ge-Ga-Se films and waveguides deposited using co-thermal evaporation and patterned with plasma etching. Strong photoluminescence at 1.54 µm with intrinsic lifetime of 1 ms was obtained from deposited films with 1490 nm excitation. Erbium population inversion up to 50% was achieved, with a maximum of ~55% possible at saturation for the first time to the author's knowledge, approaching the theoretical maximum of 65%. Whilst gain was not achieved due to the presence of upconversion pumped photoinduced absorption, this nonetheless represents a further important step towards the realization of future chalcogenide Erbium doped waveguide amplifiers at 1550 nm and in the Mid-infrared...
October 3, 2016: Optics Express
https://www.readbyqxmd.com/read/27828325/high-responsivity-sub-bandgap-hot-hole-plasmonic-schottky-detectors
#11
Mohammad Alavirad, Anthony Olivieri, Langis Roy, Pierre Berini
In this paper we present a sub-bandgap photodetector consisting of a metal grating on a thin metal patch on silicon, which makes use of the enhancement produced by the excitation of surface plasmon polaritons at the metal-silicon interface. The grating is defined via e-beam lithography and Au lift-off on a Au patch defined beforehand by optical lithography on doped p-type silicon. The surface plasmon polaritons are absorbed by the metal, leading to the creation of hot holes that can cross into the silicon where they are collected as the photocurrent...
October 3, 2016: Optics Express
https://www.readbyqxmd.com/read/27828254/ingaas-algaassb-avalanche-photodiode-with-high-gain-bandwidth-product
#12
Shiyu Xie, Xinxin Zhou, Shiyong Zhang, David J Thomson, Xia Chen, Graham T Reed, Jo Shien Ng, Chee Hing Tan
: Increasing reliance on the Internet places greater and greater demands for high-speed optical communication systems. Increasing their data transfer rate allows more data to be transferred over existing links. With optical receivers being essential to all optical links, bandwidth performance of key components in receivers, such as avalanche photodiodes (APDs), must be improved. The APDs rely on In<sub>0.53</sub>Ga<sub>0.47</sub>As (grown lattice-matched to InP substrates) to efficiently absorb and detect the optical signals with 1310 or 1550 nm wavelength, the optimal wavelengths of operation for these optical links...
October 17, 2016: Optics Express
https://www.readbyqxmd.com/read/27805703/gaussian-entanglement-distribution-with-gigahertz-bandwidth
#13
Stefan Ast, Melanie Ast, Moritz Mehmet, Roman Schnabel
The distribution of entanglement with Gaussian statistic can be used to generate a mathematically proven secure key for quantum cryptography. The distributed secret key rate is limited by the entanglement strength, the entanglement bandwidth, and the bandwidth of the photoelectric detectors. The development of a source for strongly bipartite entangled light with high bandwidth promises an increased measurement speed and a linear boost in the secure data rate. Here, we present the experimental realization of a Gaussian entanglement source with a bandwidth of more than 1...
November 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27805700/manipulation-of-beat-length-and-wavelength-dependence-of-a-polarization-beam-splitter-using-a-subwavelength-grating
#14
Lu Liu, Qingzhong Deng, Zhiping Zhou
A polarization beam splitter assisted by a subwavelength grating (SWG) is proposed. The SWG enables nearly 20-fold beat length reduction for TE, which makes the high extinction ratio (ER) possible. On the other hand, the embedded SWG preferably affects the refractive index of the even mode in the coupling region and broadens the bandwidth of the splitter. As a result, the ER of 28.7 dB (24.8 dB) for TE (TM) is obtained, while the insertion loss is only 0.10 dB (0.11 dB) at the wavelength of 1550 nm. The ER is more than 10 dB in the wavelength range of 1450-1625 nm for TE and 1495-1610 nm for TM...
November 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27805685/high-efficiency-apodized-imaging-chip-fiber-grating-coupler-for-silicon-nitride-waveguides
#15
Yang Chen, Robert Halir, Íñigo Molina-Fernández, Pavel Cheben, Jian-Jun He
Chip-fiber grating couplers have been widely used in silicon-on-insulator platforms. In silicon nitride waveguides, the lower index contrast yields gratings with a weaker radiation strength and poor directionality, thereby limiting the coupling efficiency. Here we propose and design an apodized self-imaging grating coupler in silicon nitride that images an in-plane waveguide input to an output optical fiber placed at a specific distance above the chip. Both amplitude and phase apodizations are employed to engineer the transfer function of the self-imaging grating to produce an image field matching the fiber mode profile...
November 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27805683/inverse-designed-single-step-etched-colorless-3%C3%A2-%C3%A2-db-couplers-based-on-rie-lag-insensitive-phc-like-subwavelength-structures
#16
Luluzi Lu, Deming Liu, Feiya Zhou, Dongyu Li, Mengfan Cheng, Lei Deng, Songnian Fu, Jinsong Xia, Minming Zhang
Inverse-designed free-form nanophotonic structures have shown great potential in designing ultra-compact integrated photonic devices, but strict fabrication requirements may hinder further applications. We propose here a photonic-crystal-like (PhC-like) subwavelength structure, which is insensitive to the lag effect that is the most common fabrication error. A colorless 3 dB coupler employing such a structure is designed, fabricated, and characterized. With only one-step etching, the coupling region of our final device occupies a compact footprint of 2...
November 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27805047/an-open-hardware-platform-for-optogenetics-and-photobiology
#17
Karl P Gerhardt, Evan J Olson, Sebastian M Castillo-Hair, Lucas A Hartsough, Brian P Landry, Felix Ekness, Rayka Yokoo, Eric J Gomez, Prabha Ramakrishnan, Junghae Suh, David F Savage, Jeffrey J Tabor
In optogenetics, researchers use light and genetically encoded photoreceptors to control biological processes with unmatched precision. However, outside of neuroscience, the impact of optogenetics has been limited by a lack of user-friendly, flexible, accessible hardware. Here, we engineer the Light Plate Apparatus (LPA), a device that can deliver two independent 310 to 1550 nm light signals to each well of a 24-well plate with intensity control over three orders of magnitude and millisecond resolution. Signals are programmed using an intuitive web tool named Iris...
November 2, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27757943/enhanced-emission-of-quantum-system-in-si-ge-nanolayer-structure
#18
Zhong-Mei Huang, Wei-Qi Huang, Tai-Ge Dong, Gang Wang, Xue-Ke Wu
It is very interesting that the enhanced peaks near 1150 and 1550 nm are observed in the photoluminescence (PL) spectra in the quantum system of Si-Ge nanolayer structure, which have the emission characteristics of a three-level system with quantum dots (QDs) pumping and emission of quasi-direct-gap band, in our experiment. In the preparing process of Si-Ge nanolayer structure by using a pulsed laser deposition method, it is discovered that the nanocrystals of Si and Ge grow in the (100) and (111) directions after annealing or electron beam irradiation...
December 2016: Nanoscale Research Letters
https://www.readbyqxmd.com/read/27749851/plasmonic-enhanced-two-photon-absorption-in-silicon-photodetectors-for-optical-correlators-in-the-near-infrared
#19
Alexei Smolyaninov, Mu-Han Yang, Lin Pang, Yeshaiahu Fainman
A high-density array of plasmonic coaxial nanoantennas is used to enhance the two-photon absorption (TPA) process in a conventional silicon photodetector from a mode-locked 76 MHz Ti:sapphire laser over a spectral range from 1340 to 1550 nm. This enhanced TPA was used to generate an interferometric autocorrelation trace of a 150 fs laser pulse. Unlike second-harmonic generation, this technique does not require phase matching or a bulky crystal and can be used on a low-cost integrated silicon platform over a wide range of near-IR wavelengths compatible with modern commercial tunable femtosecond sources...
October 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27738837/utilizing-non-ablative-fractional-photothermolysis-prior-to-ala-photodynamic-therapy-in-the-treatment-of-acne-vulgaris-a-case-series
#20
Sarah Qureshi, Jennifer Y Lin
Aminolevulinic acid (ALA) photodynamic therapy (PDT) is an emerging modality in the treatment of acne. While ablative fractional lasers have been used to enhance drug delivery into the epidermis, recent evidence suggests that non-ablative fractional photothermolysis may also improve uptake of ALA. We explored the use of non-ablative 1550 nm laser as a safe alternative in the delivery of ALA prior to red-light PDT for refractory inflammatory and cystic acne. Subjects referred for treatment of acne refractory to several topical and oral regimens, including isotretinoin, were pre-treated with non-ablative fractional photothermolysis (NAFP)...
October 14, 2016: Lasers in Medical Science
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