Optimization of laser stabilization via self-injection locking to a whispering-gallery-mode microresonator: experimental study

Self-injection locking of a diode laser to a high-quality-factor microresonator is widely used for frequency stabilization and linewidth narrowing. We constructed several microresonator-based laser sources with measured instantaneous linewidths of 1 Hz and used them for investigation and implementation of the self-injection locking effect. We studied analytically and experimentally the dependence of the stabilization coefficient on tunable parameters such as locking phase and coupling rate. It was shown that precise control of the locking phase allows fine tuning of the generated frequency from the stabilized laser diode. We also showed that it is possible for such laser sources to realize fast continuous and linear frequency modulation by injection current tuning inside the self-injection locking regime. We conceptually demonstrate coherent frequency-modulated continuous wave LIDAR over a distance of 10 km using such a microresonator-stabilized laser diode in the frequency-chirping regime and measure velocities as low as sub-micrometer per second in the unmodulated case. These results could be of interest for cutting-edge technology applications such as space debris monitoring and long-range object classification, high resolution spectroscopy and others

Two-particle correlations in azimuthal angle and pseudorapidity in inelastic p + p interactions at the CERN Super Proton Synchrotron

Results on two-particle ΔηΔϕ correlations in inelastic p + p interactions at 20, 31, 40, 80, and 158 GeV/c are presented. The measurements were performed using the large acceptance NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The data show structures which can be attributed mainly to effects of resonance decays, momentum conservation, and quantum statistics. The results are compared with the Epos and UrQMD models.ISSN:1434-6044ISSN:1434-605

Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

MODELLING OF FATIGUE STRENGTH AND DURABILITY IN STRUCTURAL STEELS TAKING LOADING ASYMMETRY INTO CONSIDERATION

The fatigue strength and cyclic creepage of the structural steels have been investigated. The engineering method for design of the fatigue curves at asymmetric loading by a soft cycle has been developed. The models of the fatigue strength and cyclic creepage have been created. The tests for cyclic strength and creepage at axial loading of the cylindric samples have been made on the hydropulsator at frequency 350 cycles/min. The strength cycle asymmetry coefficients were changed with limits from -4 to +0,75. The known dependence describing the fatigue curve at rigid straining has been modified on base of the obtained experimental data: the effective plasticity function modeling the material embrittlement with durability growth has been introduced instead located plasticity constant. At soft loading cycle the design is made on base of the modified formula at transfer from deformations to the stresses by means of the extension diagram. The methods for determination of the free parameters in the fatigue strength model have been developed. The cyclic creepage model for given loading conditions in the specified asymmetry fields of the stress cycle has been developed, the methods for determination of its parameters have been proposed. The results of the separate work stages have been introduced at the Institute of Strength Problems (Ukraine Academy of Sciences) and at the enterprises.Available from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Peculiarities of neurostimulation by intense nanosecond pulsed electric fields: how to avoid firing in peripheral nerve fibers

Intense pulsed electric fields (PEF) are a novel modality for the efficient and targeted ablation of tumors by electroporation. The major adverse side effects of PEF therapies are strong involuntary muscle contractions and pain. Nanosecond-range PEF (nsPEF) are less efficient at neurostimulation and can be employed to minimize such side effects. We quantified the impact of the electrode configuration, PEF strength (up to 20 kV/cm), repetition rate (up to 3 MHz), bi- and triphasic pulse shapes, and pulse duration (down to 10 ns) on eliciting compound action potentials (CAPs) in nerve fibers. The excitation thresholds for single unipolar but not bipolar stimuli followed the classic strength-duration dependence. The addition of the opposite polarity phase for nsPEF increased the excitation threshold, with symmetrical bipolar nsPEF being the least efficient. Stimulation by nsPEF bursts decreased the excitation threshold as a power function above a critical duty cycle of 0.1%. The threshold reduction was much weaker for symmetrical bipolar nsPEF. Supramaximal stimulation by high-rate nsPEF bursts elicited only a single CAP as long as the burst duration did not exceed the nerve refractory period. Such brief bursts of bipolar nsPEF could be the best choice to minimize neuromuscular stimulation in ablation therapies.info:eu-repo/semantics/publishedVersio

Self-injection locking of a laser diode to a high-Q silicon WGM microresonator

The key properties of the self-injection locking regime of a laser diode to a high-Q microresonator with whispering gallery mode made of crystalline silicon are considered. It has been experimentally demonstrated the possibility of the self-injection locking using cavity made of crystalline silicon. This result opens up new possibilities for creating narrow-band highly stable laser sources in midIR, over 2.3 microns, on a new hardware base

Self-injection locking of a laser diode to a high-Q silicon WGM microresonator

The key properties of the self-injection locking regime of a laser diode to a high-Q microresonator with whispering gallery mode made of crystalline silicon are considered. It has been experimentally demonstrated the possibility of the self-injection locking using cavity made of crystalline silicon. This result opens up new possibilities for creating narrow-band highly stable laser sources in midIR, over 2.3 microns, on a new hardware base

Vanadium Oxide-Poly(3,4-ethylenedioxythiophene) Nanocomposite as High-Performance Cathode for Aqueous Zn-Ion Batteries: The Structural and Electrochemical Characterization

In this work the nanocomposite of vanadium oxide with conducting polymer poly(3,4-ethylenedioxythiophene) (VO@PEDOT) was obtained by microwave-assisted hydrothermal synthesis. The detailed study of its structural and electrochemical properties as cathode of aqueous zinc-ion battery was performed by scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction analysis, X-ray photoelectron spectroscopy, thermogravimetric analysis, cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The initial VO@PEDOT composite has layered nanosheets structure with thickness of about 30–80 nm, which are assembled into wavy agglomerated thicker layers of up to 0.3–0.6 μm. The phase composition of the samples was determined by XRD analysis which confirmed lamellar structure of vanadium oxide V10O24∙12H2O with interlayer distance of about 13.6 Å. The VO@PEDOT composite demonstrates excellent electrochemical performance, reaching specific capacities of up to 390 mA∙h∙g−1 at 0.3 A∙g−1. Moreover, the electrodes retain specific capacity of 100 mA∙h∙g−1 at a high current density of 20 A∙g−1. The phase transformations of VO@PEDOT electrodes during the cycling were studied at different degrees of charge/discharge by using ex situ XRD measurements. The results of ex situ XRD allow us to conclude that the reversible zinc ion intercalation occurs in stable zinc pyrovanadate structures formed during discharge