Investigation of motion control of piezoelectric unimorph for laser shutter systems

This paper presents the design and testing of a resonance frequency-tunable piezoelectric unimorph chopper and shutter that employ a magnetic force technique and magnetorheological fluid (MRF). This technique enabled to increase the frequency of the resonance up to 110% of the untuned resonant frequency. A piezoelectric unimorph cantilever with a natural frequency of 126 Hz is used as the laser beam chopper or shutter, which is successfully tuned in a frequency range of 126 - 270 Hz thereby enabling continuous control of the laser beam over the entire frequency range tested. A theoretical model based on variable magnetic field strength and MRF damping is presented. The magnetic force and MRF applied for damping of transient vibrations of the piezoelectric unimorph shutter have been experimentally determine

Control of piezoelectric scanner dynamics using magnetorheological fluid

The developed one-dimensional laser beam scanner, driven by a piezoelectric disctype unimorph actuator is presented in this paper. The dynamics of a piezoelectric actuator is analyzed. A magnetorheological fluid (MRF) damper is used to eliminate transient vibrations of the scanner eigen frequencies induced by the stepped driving voltage. Experimental results demonstrate the effectiveness of the MRF damper in residual-vibration reduction in the laser beam scanner

Investigation of motion control of piezoelectric unimorph for laser shutter systems

This paper presents the design and testing of a resonance frequency-tunable piezoelectric unimorph chopper and shutter that employ a magnetic force technique and magnetorheological fluid (MRF). This technique enabled to increase the frequency of the resonance up to 110% of the untuned resonant frequency. A piezoelectric unimorph cantilever with a natural frequency of 126 Hz is used as the laser beam chopper or shutter, which is successfully tuned in a frequency range of 126 - 270 Hz thereby enabling continuous control of the laser beam over the entire frequency range tested. A theoretical model based on variable magnetic field strength and MRF damping is presented. The magnetic force and MRF applied for damping of transient vibrations of the piezoelectric unimorph shutter have been experimentally determine

Investigation of motion control of piezoelectric unimorph for laser shutter systems

This paper presents the design and testing of a resonance frequency-tunable piezoelectric unimorph chopper and shutter that employ a magnetic force technique and magnetorheological fluid (MRF). This technique enabled to increase the frequency of the resonance up to 110% of the untuned resonant frequency. A piezoelectric unimorph cantilever with a natural frequency of 126 Hz is used as the laser beam chopper or shutter, which is successfully tuned in a frequency range of 126 - 270 Hz thereby enabling continuous control of the laser beam over the entire frequency range tested. A theoretical model based on variable magnetic field strength and MRF damping is presented. The magnetic force and MRF applied for damping of transient vibrations of the piezoelectric unimorph shutter have been experimentally determine

SiN foundry platform for high performance visible light integrated photonics

We present a high performance silicon nitride photonic integrated circuit platform operating at visible wavelengths, accessible through the commercial foundry, LIGENTEC. Propagation losses were measured across the visible spectrum from 450 nm to 850 nm. For wavelengths above 630 nm, losses were < 1 / in TE and < 0.5 / in TM. Additionally, sets of single mode waveguide-coupled ring resonators across three separate chips were tested and analysed. A peak intrinsic Q factor of 3.69 × 106 was measured for a single resonance at ∼635.3 nm, with an average value of 2.28 × 106 recorded over 10 peaks in a 3 nm tuning range. Analyses of the loss and coupling, as functions of bus-ring coupling gap and waveguide width, are also presented. High confinement, low loss devices realised on the chip-scale in a wide-bandgap material like silicon nitride are increasingly important for the next generation of integrated optical devices operating at visible wavelengths

Covert dissemination of carbapenemase-producing Klebsiella pneumoniae (KPC) in a successfully controlled outbreak: long and short-read whole-genome sequencing demonstrate multiple genetic modes of transmission

Background: Carbapenemase-producing Enterobacteriaceae (CPE), including KPC-producing Klebsiella pneumoniae (KPC-Kpn), are an increasing threat to patient safety. Objectives: To use WGS to investigate the extent and complexity of carbapenemase gene dissemination in a controlled KPC outbreak. Materials and methods: Enterobacteriaceae with reduced ertapenem susceptibility recovered from rectal screening swabs/clinical samples, during a 3 month KPC outbreak (2013–14), were investigated for carbapenemase production, antimicrobial susceptibility, variable-number-tandem-repeat profile and WGS [short-read (Illumina), long-read (MinION)]. Short-read sequences were used for MLST and plasmid/Tn4401 fingerprinting, and long-read sequence assemblies for plasmid identification. Phylogenetic analysis used IQTree followed by ClonalFrameML, and outbreak transmission dynamics were inferred using SCOTTI. Results: Twenty patients harboured KPC-positive isolates (6 infected, 14 colonized), and 23 distinct KPC-producing Enterobacteriaceae were identified. Four distinct KPC plasmids were characterized but of 20 KPC-Kpn (from six STs), 17 isolates shared a single pKpQIL-D2 KPC plasmid. All isolates had an identical transposon (Tn4401a), except one KPC-Kpn (ST661) with a single nucleotide variant. A sporadic case of KPC-Kpn (ST491) with Tn4401a-carrying pKpQILD2 plasmid was identified 10 months before the outbreak. This plasmid was later seen in two other species and other KPC-Kpn (ST14,ST661) including clonal spread of KPC-Kpn (ST661) from a symptomatic case to nine ward contacts. Conclusions: WGS of outbreak KPC isolates demonstrated blaKPC dissemination via horizontal transposition (Tn4401a), plasmid spread (pKpQIL-D2) and clonal spread (K. pneumoniae ST661). Despite rapid outbreak control, considerable dissemination of blaKPC still occurred among K. pneumoniae and other Enterobacteriaceae, emphasizing its high transmission potential and the need for enhanced control efforts

Foundry SiN as a platform for heterogeneous integration at visible wavelengths

Silicon nitride (Si 3 N 4 ) is an excellent material platform for visible wavelength photonic integrated circuits, in particular, as a host for the heterogeneous/hybrid integration of complementary materials. In this work, we characterise the performance of the Si 3 N 4 from LIGENTEC as a base for hybrid integration

Electrical Control of Optical Emitter Relaxation Pathways enabled by Graphene

Controlling the energy flow processes and the associated energy relaxation rates of a light emitter is of high fundamental interest, and has many applications in the fields of quantum optics, photovoltaics, photodetection, biosensing and light emission. While advanced dielectric and metallic systems have been developed to tailor the interaction between an emitter and its environment, active control of the energy flow has remained challenging. Here, we demonstrate in-situ electrical control of the relaxation pathways of excited erbium ions, which emit light at the technologically relevant telecommunication wavelength of 1.5 $\mu$m. By placing the erbium at a few nanometres distance from graphene, we modify the relaxation rate by more than a factor of three, and control whether the emitter decays into either electron-hole pairs, emitted photons or graphene near-infrared plasmons, confined to $<$15 nm to the sheet. These capabilities to dictate optical energy transfer processes through electrical control of the local density of optical states constitute a new paradigm for active (quantum) photonics.Comment: 9 pages, 4 figure