Microring-resonator-based sensor measuring both the concentration and temperature of a solution

We propose and investigate experimentally a micro-ring-resonator-based sensor with which we can measure both the concentration and temperature of glucose solution. It consists of two micro-ring resonators consecutively coupled to a bus waveguide by the overlap between them. The resonance wavelengths of the two resonators change similarly with the temperature but differently with the concentration. For that purpose, the core of just one micro-ring resonator is exposed directly to the solution. Using polymers, conventional processes, and a polymer lift-off process, we implement the sensor. Through the measurement of the fabricated sensor, we obtain its characteristics of measuring the temperature and concentration.open273

Entertaining, Informing, Persuading: Figures of Speech to Prepare for Health and Safety

The public mandates science center exhibits that are entertaining as well as informative. In addition, exhibits can also be performative, in that they act back upon the visitors with an injunction to change their ways. We give examples from two exhibits that not only inform, but also open up space for changes in behavior and perception, particularly in arenas of public health. We look at two recent and ongoing exhibits at MOSI – “Disasterville” and “The Amazing You” - and examine the affordances suggested by figures of speech such as eponymy, hyponymy, hypernymy and retronymy. Tropological research into museum exhibits appears to open up new lines of scholarship for understanding persuasion

Investigation of noise sources in the LTP interferometer S2-AEI-TN-3028

All breadboards for the LTP interferometer showed an extra noise term that was, until recently, not fully understood. In this report that noise term is investigated in detail. It turns out that it is caused by sidebands on the light. In our lab, these sidebands were caused by nonlinear mixing processes in the power amplifiers that drive the AOM, if electromagnetic interference at a frequency near the operating frequency (ca. 80 MHz) is picked up by the power amplifier. The disturbing nearby frequency is the frequency of the other AOM, with a difference of exactly f_het, causing multiple sidebands at integer multiples of f_het from the carrier. They appear as pairs with a phase relationship that corresponds to phase-modulation (PM). Experiments with a very different electrical setup (in Glasgow) also showed sidebands which demonstrates that they are not caused by peculiarities of the Hannover setup. While the effect of a pair of first-order PM sidebands cancels and causes no harm, only one of the second-order sidebands produces noise which cannot be cancelled by its second-order mirror image. Hence the second-order sidebands are the dominant noise source. Various strategies of mitigation are also investigated. The two most important ones, both of which are already implemented as baseline for the LTP interferometer, are (1) to reduce the sidebands by careful EMC design and dedicated testing, and (2) to stabilize the optical pathlength difference (OPD) between the two fibers with a Piezo device. The combination of these two measures will reduce this error term to insignificance. We have also investigated other noise sources such as laser amplitude noise and beam jitter noise. Laser amplitude noise does have an influence on the total performance of the interferometer. Using a laser amplitude stabilization (part of the baseline), its influence can also be sufficiently reduced. Contrary to earlier worries, we did not find a significant noise contribution from beam jitter noise in conjunction with quadrant photodiodes. As part of this investigation we have also developed a mathematical model for the sideband coupling that fully describes their effect and has been experimentally verified. Furthermore we have developed various numerical procedures to find correlations between auxiliary data streams (such as alignment signals) and the main interferometer output. They are useful for diagnostic purposes, but in general too complex to implement on LTP. Using only those procedures that are the baseline for the FM, the noise performance of the LTP EM interferometer in the lab is now well below its specifications at all frequencies, with remaining noise sources mainly driven by ground-based disturbances, such that we are confident that the LTP interferometer will perform well on orbit and will enable the detailed study of the behaviour and noise performance of the inertial sensor and DFACS systems, which indeed is the primary job of the interferometer. Comment of the Author: Version 1.2 2008/07/0

Subtraction of test mass angular noise in the LISA Technology Package interferometer

We present recent sensitivity measurements of the LISA Technology Package interferometer with articulated mirrors as test masses, actuated by piezo-electric transducers. The required longitudinal displacement resolution of 9 pm/sqrt[Hz] above 3 mHz has been demonstrated with an angular noise that corresponds to the expected in on-orbit operation. The excess noise contribution of this test mass jitter onto the sensitive displacement readout was completely subtracted by fitting the angular interferometric data streams to the longitudinal displacement measurement. Thus, this cross-coupling constitutes no limitation to the required performance of the LISA Technology Package interferometry.Comment: Applied Physics B - Lasers and Optics (2008

Intrabeam scattering analysis of measurements at KEK's ATF damping ring

We derive a simple relation for estimating the relative emittance growth in x and y due to intrabeam scattering (IBS) in electron storage rings. We show that IBS calculations for the ATF damping ring, when using the formalism of Bjorken-Mtingwa, a modified formalism of Piwinski (where eta squared divided by beta has been replaced by the dispersion invariant), or a simple high-energy approximate formula all give results that agree well. Comparing theory, including the effect of potential well bunch lengthening, with a complete set of ATF steady-state beam size vs. current measurements we find reasonably good agreement for energy spread and horizontal emittance. The measured vertical emittance, however, is larger than theory in both offset (zero current emittance) and slope (emittance change with current). The slope error indicates measurement error and/or additional current-dependent physics at the ATF; the offset error, that the assumed Coulomb log is correct to within a factor of 1.75.Comment: 17 pages, 6 figures, .bbl fil

BaFe12O19 single-particle-chain nanofibers : preparation, characterization, formation principle, and magnetization reversal mechanism

BaFe12O19 single-particle-chain nanofibers have been successfully prepared by an electrospinning method and calcination process, and their morphology, chemistry, and crystal structure have been characterized at the nanoscale. It is found that individual BaFe12O19 nanofibers consist of single nanoparticles which are found to stack along the nanofiber axis. The chemical analysis shows that the atomic ratio of Ba/Fe is 1:12, suggesting a BaFe12O19 composition. The crystal structure of the BaFe12O19 single-particle-chain nanofibers is proved to be M-type hexagonal. The single crystallites on each BaFe12O19 single-particlechain nanofibers have random orientations. A formation mechanism is proposed based on thermogravimetry/differential thermal analysis (TG-DTA), X-ray diffraction (XRD), and transmission electron microscopy (TEM) at six temperatures, 250, 400, 500, 600, 650, and 800 �C. The magnetic measurement of the BaFe12O19 single-particle-chain nanofibers reveals that the coercivity reaches a maximum of 5943 Oe and the saturated magnetization is 71.5 emu/g at room temperature. Theoretical analysis at the micromagnetism level is adapted to describe the magnetic behavior of the BaFe12O19 single-particle-chain nanofibers

Status of the low emittance upgrade of the advanced light source

The Advanced Light Source is one of the earliest 3rd generation light sources. With an active upgrade program it has remained competitive over the years. The latest in a series of upgrades is a lattice upgrade project that was started in 2009. When it will be completed, the ALS will operate with a horizontal emittance of 2.2 nm and an effective emittance of 2.6 nm. Combined with the high current of 500 mA and the small vertical emittance the ALS already operates at, this upgrade will keep it competitive for years to come. This paper summarizes the status of the upgrade, including beam dynamics studies and lattice optimizations as well as the magnet design

Metal-slotted polymer optical waveguide device

Metal-slotted optical waveguides (MSOWs) using an electro-optic polymer material have been experimentally demonstrated. The device consists of a three-layered slab waveguide in that the thin metal (gold) film strips are embedded on top of the lower cladding. The optical mode shapes and effective index of the propagation modes of the proposed waveguide structure were calculated using a simplified effective index method and a simulation tool. The fabrication and the device characteristics of a variable optical attenuator and an optical phase modulator based on MSOWs are discussed.open5

Design and construction of an optical test bed for LISA imaging systems and tilt-to-length coupling

The laser interferometer space antenna (LISA) is a future space-based interferometric gravitational-wave detector consisting of three spacecraft in a triangular configuration. The interferometric measurements of path length changes between satellites will be performed on optical benches in the satellites. Angular misalignments of the interfering beams couple into the length measurement and represent a significant noise source. Imaging systems will be used to reduce this tilt-to-length coupling. We designed and constructed an optical test bed to experimentally investigate tilt-to-length coupling. It consists of two separate structures, a minimal optical bench and a telescope simulator. The minimal optical bench comprises the science interferometer where the local laser is interfered with light from a remote spacecraft. In our experiment, a simulated version of this received beam is generated on the telescope simulator. The telescope simulator provides a tilting beam, a reference interferometer and an additional static beam as a phase reference. The tilting beam can either be a flat-top beam or a Gaussian beam. We avoid tilt-to-length coupling in the reference interferometer by using a small photo diode placed at an image of the beam rotation point. We show that the test bed is operational with an initial measurement of tilt-to-length coupling without imaging systems. Furthermore, we show the design of two different imaging systems whose performance will be investigated in future experiments

Status of the ALS brightness upgrade

The Advanced Light Source (ALS) at Berkeley Lab while one of the earliest 3rdgeneration light sources remains one of the brightest sources for soft x-rays worldwide. Amultiyear upgrade of the ALS is currently under way, which includes new and replacementx-ray beamlines, a replacement of many of the original insertion devices and many upgradesto the accelerator. The accelerator upgrade that affects the ALS performance most directlyis the ALS brightness upgrade, which will reduce the horizontal emittance from 6.3 to 2.2nm (2.6 nm effective). This will result in a brightness increase by a factor of three forbendmagnet beamlines and at least a factor of two for insertion device beamlines. Magnetsfor this upgrade are currently in production and will be installed starting later thisyear. Copyright © 2012 by IEEE