Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Combining silicon-based lithium niobate modulator and silicon-based Si<jats:sub>3</jats:sub>N<jats:sub>4</jats:sub> resonator with silicon-based photonics technology, a highly systematic design of hybrid integrated optical gyroscope with enhanced reciprocity sensitivity <jats:bold>and dual micro-ring structure is proposed for the first time in the paper</jats:bold>, and the relationship between device’s structural parameters and optical performance is analyzed by constructing a complete simulation link, which provides a theoretical design reference for improving the system sensitivity. <jats:bold>When</jats:bold> the wavelength is 1550 nm, conversion frequency of the dual-ring optical path is 50 MHz, coupling coefficient is 0.2, and the radius <jats:bold> <jats:italic>R</jats:italic> </jats:bold> is 1000 μm, the quality factor of the silicon-based Si<jats:sub>3</jats:sub>N<jats:sub>4</jats:sub> resonator is 2.58×10<jats:sup>5</jats:sup>, which is 1.58 times that of the silicon on insulator resonator. Besides, <jats:bold>the effective number of times the light travels around the ring before leaving the micro-ring is 5.93</jats:bold>, which is 1.62 times that of the silicon on insulator resonator. The work fits the gyro dynamic output diagram, and solves the problem of low sensitivity at low speed by setting the phase offset. The results provide a basis for the further optimization of design and chip processing of the integrated optical gyroscope.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>By introducing a thin p-type layer between the Schottky metal and n-GaN layer, this work presents a Schottky-pn junction diode (SPND) configuration for the GaN rectifier fabrication. Specific unipolar carrier conduction characteristic is demonstrated by the verification of temperature-dependent current-voltage (<jats:italic>I</jats:italic>-<jats:italic>V</jats:italic>) tests and electroluminescence spectra. Meanwhile, apparently advantageous forward conduction properties as compared to the pn diode fabricated on the same wafer have been achieved, featuring a lower turn-on voltage of 0.82 V. Together with the analysis model established in the GaN SPND for a wide-range designable turn-on voltage, this work provides an alternative method to the GaN rectifier strategies besides the traditional solution.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>A miniaturized atomic spin-exchange relaxation-free (SERF) co-magnetometer measures angular velocity using a balanced polarimetry technique which is easily affected by the laser power. A laser power closed-loop control system is usually used to suppress the fluctuation of the laser power. Although this method can greatly eliminate the fluctuation of the in-loop laser power (the feedback laser), it cannot fully eliminate the fluctuation of the out-of-loop laser power (the signal measurement laser). This leads to SERF gyroscope laser power error, which reduces the inertial measurement accuracy. In this paper, the influence mechanism of the split ratio (the ratio of the in-loop laser power to the out-of-loop laser power) on the out-of-loop laser power control accuracy is analyzed by establishing a laser power transmission model inside and outside the loop. Moreover, a method is developed to improve the out-of-loop laser power stability by optimizing the split ratio. Comparative experiments showed that the relative Allan standard deviation of the out-of-loop laser power decreased from 5.48×10<jats:sup>-6</jats:sup> to 2.62×10<jats:sup>-6</jats:sup> at 100 s, and decreased by an order of magnitude from 1.76×10<jats:sup>-5</jats:sup> to 3.30×10<jats:sup>-6</jats:sup> at 1000 s. Correspondingly, the rate ramp coefficient in the Allan standard deviation curve of the SERF gyroscope test data decreased from 1.312 °/h/h to 0.246 °/h/h. And the bias stability increased from 0.032 °/h to 0.019 °/h. Therefore, the proposed method can improve the long-term stability of the probe laser power and effectively suppress the laser power error of the SERF gyroscope.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>This paper investigates fault-tolerant finite-time dynamical consensus problems of double-integrator multi-agent systems (MASs) with partial agents subject to synchronous self-sensing function failure (SSFF). A strategy of recovering the connectivity of network topology among normal agents based on multi-hop communication and a fault-tolerant finite-time dynamical consensus protocol with time-varying gains are proposed to resist synchronous SSFF. It is proved that double-integrator MASs with partial agents subject to synchronous SSFF using the proposed strategy of network topology connectivity recovery and fault-tolerant finite-time dynamical consensus protocol with the proper time-varying gains can achieve finite-time dynamical consensus. Numerical simulations are given to illustrate the effectiveness of the theoretical results.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Linear carbon chains as new one-dimensional nanomaterials attract attention for the predicted outstanding properties. However, the high reactivity of linear carbon chains hampers further experimental research. To date, different methods have been developed to synthesize new materials containing linear carbon chains. Among them, the arc-discharge method is a practical way to prepare both finite and infinite linear carbon chains. This review provides a brief discussion of the recent progress in the techniques to prepare carbon chain-based materials and then focuses on the arc-discharge method. The configuration of apparatus, optimal conditions and corresponding mechanism of arc-discharge method to prepare long linear carbon chain inside multi-walled carbon nanotubes are summarized in detail. The characterization techniques are introduced to evaluate the quality of products. Moreover, remaining challenges and perspectives are presented for further investigation of long linear carbon chains.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>CePdAl has been recently recognized as a frustrated antiferromagnetic heavy-fermion compound with a pressure- or field-tuned, extended quantum critical phase at zero temperature. Identifying characteristic signatures of the emerging quantum critical phase, which are expected to be distinct from those near a quantum critical point, remains challenging. In this work, by performing ultrasonic and thermoelectric measurements down to very low temperatures in a <jats:sup>3</jats:sup>He-<jats:sup>4</jats:sup>He dilution refrigerator in the presence of magnetic field, we are able to obtain some crucial thermodynamic and thermal transport features of the quantum critical phase, including a frustration-related elastic softening detected by ultrasound and a Fermi-surface change probed by thermoelectric effect.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report a compact, efficient optical parametric oscillator (OPO) based on a periodically poled potassium titanyl phosphate (PPKTP) crystal pumped by a 532 nm laser, which generated 1.51 W of average power at the signal wavelength of 709 nm with the pulse duration of ~1.0 ns. The extraction efficiency was up to 59%. To the best of our knowledge, this is the first report on watt-level green-pumped PPKTP-based singly-resonant oscillator OPO (SRO-OPO). The precise build-up time of OPO was determined of 1.6 ns benefitting from the characteristic of twin-peak pulse profile of pump beam. The spectrum width of the idler was also measured to be 4.2 nm with the central wavelength of 2134 nm at 0.2 nm spectral resolution of optical spectrum analyzer. In addition, the beam quality of <jats:italic>M</jats:italic> <jats:sup>2</jats:sup> &amp;#60; 1.9 of generated signal exhibited a good consistency with <jats:italic>M</jats:italic> <jats:sup>2</jats:sup> &amp;#60; 1.5 for the pump source.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>CS molecule, which plays a key role in atmospheric and astrophysical circumstances, has drawn great attentions for long time. Owing to its large state density, the detailed information of the electronic structure of CS is still lacking. In this work, the high-level MRCI+Q method is used to compute the potential energy curves, dipole moments and transition dipole moments of singlet and triplet states correlated with the lowest dissociation limit of CS, based on which high accurate vibration-rotation levels and spectroscopic constants of bound states are evaluated. The opacity of CS relevant to atmospheric circumstance are computed at a pressure of 100 atms for different temperatures. With the increasing of temperature, band systems from different transitions mingle with each other, and band boundaries become blurred, which are originated from the increased population on vibrational excited states and electronic excited state at high temperature.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Caesium atomic fountain clock is a primary frequency standard. During its operation, Majorana transition frequency shift will occur once a magnetic field at some special locations along the atomic trajectory is singular. In this study, by developing a physical model, we analysed the magnetic field requirements for atomic adiabatic transition, and calculated the influence of the Majorana atomic transition on the atomic state via a quantum method. Based on the simulation results of the magnetic field in the fountain clock, we applied the Monte Carlo method to simulate the relationship between the Majorana transition frequency shift and magnetic field at the entrance of magnetic shieldings, as well as the initial atomic population. The measurement of the Majorana transition frequency shift was realized by state-selecting asymmetrically populated atoms. The relationship between the Majorana transition frequency shift and axial magnetic field at the entrance of magnetic shieldings was obtained. The measured results were essentially consistent with the calculated results. Thus, the magnetic field at the entrance of magnetic shield was configured, and the Majorana transition frequency shift of the fountain clock was calculated to be 4.57×10<jats:sup>-18</jats:sup>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Classical molecular dynamics simulations with global neural network machine learning potential have been used to study early-stage oxidation and dissolution behaviors of bcc Fe surfaces contacting with stagnant oxygen dissolved liquid lead-bismuth eutectic (LBE-O). Both static and dynamic simulation results indicate that the early-stage oxidation and dissolution behaviors of bcc Fe show strong orientation dependence under the liquid LBE environments, which may explain experimental observations of uneven interface between iron-based materials and liquid LBE. Our investigations show that it is the delicate balance between the oxide growth and metal dissolution that leads to the observed corrosion anisotropy for bcc Fe contacting with liquid LBE-O.</jats:p>