Catálogo de publicaciones - revistas

<jats:p>Linear and nonlinear dust acoustic (DA) waves have been investigated in an opposite polarity dusty plasma comprising negatively and positively charged dust grains, Maxwellian electrons and ions, including the generalized polarization force effect. The properties of linear DA waves have been significantly altered by the dual dust polarity and polarization force. Large amplitude DA solitons have been discussed in the framework of the Sagdeev potential technique. Our results show that both rarefactive and compressive solitons can exist in such a dusty plasma. The basic features of the Sagdeev potential have been examined under the effect of the polarization force parameter <jats:italic>R</jats:italic>, the ratio of the charge number of the positive dust to that of the negative dust <jats:italic>Z</jats:italic>, and the Mach number <jats:italic>M</jats:italic>. The results show that these parameters play a significant role in determining the region of existence of large amplitude DA solitons.</jats:p>

<jats:p>A new design of staggered array semi-packed micro gas chromatographic column was presented based on the micro electromechanical system (MEMS) technology. It was a sensor for gas sample analysis. The internal velocity fields of ten types of semi-packed micro gas chromatographic column were studied. The effects of array spacing and dislocation spacing on the flow field distribution were investigated. The results show that on the basis of ensuring the formation of virtual wall, with the increase of array spacing, the maximum velocity difference between the flow channels in the vertical direction decreases gradually, but the velocity difference in the flow channels <jats:italic>a</jats:italic> and <jats:italic>b</jats:italic> increases. When the inlet velocity was set to be 0.18 m/s, the maximum velocity difference in the channel of the staggered semi-packed micro gas chromatography column 3 (CSAC3) was 0.05610 m/s. The maximum velocity difference in the channel <jats:italic>a</jats:italic> was 0.09160 m/s. The maximum velocity difference in the channel <jats:italic>b</jats:italic> was 0.02401 m/s. CSAC3 had a more uniform velocity field distribution, which can effectively suppress the laminar flow effect during chromatographic separation, and had a smaller pressure distribution, which puts forward lower requirements for carrier gas system. The staggered array semi-packed micro gas chromatography column proposed in this paper can effectively improve the velocity field distribution and pressure distribution in the channel, and provide a theoretical basis for the design of the new micro gas chromatography column structure.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We develop a highly efficient scheme for numerically solving the three-dimensional time-dependent Schrödinger equation of the single-active-electron atom in the field of laser pulses by combining smooth exterior complex scaling (SECS) absorbing method and Arnoldi propagation method. Such combination has not been reported in the literature. The proposed scheme is particularly useful in the applications involving long-time wave propagation. The SECS is a wonderful absorber, but its application results in a non-Hermitian Hamiltonian, invalidating propagators utilizing the Hermitian symmetry of the Hamiltonian. We demonstrate that the routine Arnoldi propagator can be modified to treat the non-Hermitian Hamiltonian. The efficiency of the proposed scheme is checked by tracking the time-dependent electron wave packet in the case of both weak extreme ultraviolet (XUV) and strong infrared (IR) laser pulses. Both perfect absorption and stable propagation are observed.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>A hybrid metamaterial with the integration of molybdenum disulfide (MoS<jats:sub>2</jats:sub>) overlayer is proposed to manipulate the terahertz (THz) wave. The simulated results indicate that the introduction of MoS<jats:sub>2</jats:sub> layer could significantly modify the resonant responses with large resonance red-shift and bandwidth broadening due to the depolarization field effect, especially for the structure on the small permitivity substrate. Additionally, the wide-band modulator in off-resonant region and a switch effect at resonance can be achieved by varying the conductivity of MoS<jats:sub>2</jats:sub> layer. Further theoretical calculations based on the Lorentz coupling model are consistent with the simulated results, explicating the response behaviors originate from the coupling between MoS<jats:sub>2</jats:sub> overlayer and the metastructure. Our results could provide a possibility for active control THz modulator and switchable device based on the MoS<jats:sub>2</jats:sub> overlayer and advance the understanding of the coupling mechanism in hybrid structures.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>A novel bandpass filter (BPF) based on spoof surface plasmon polaritons (SSPPs) using a compact folded slotline structure is proposed and experimentally demonstrated. The proposed novel SSPPs structure compared with a conventional plasmonic waveguide with slot line SSPPs unit structure at the same size, the considerable advantages in much lower asymptotic frequency with tight field confinement, which enable the proposed filter to be more miniaturization. A high-efficient mode conversion structure is designed to transition from TE-mode to SSPPs-mode by gradient slotline lengths. The low-frequency stop-band can be committed with microstrip to slotline evolution on both sides of the dielectric, while the high-frequency cutoff band is realized by the proposed SSPPs structure. The influence of dispersion relation, electric field distribution, surface current, and structural parameters on the transmission characteristics of the proposed BPF are analyzed by finite difference time domain (FDTD). To validate the design concept, the prototype of the miniaturized SSPPs BPF has been manufactured and measured. The experimental results show high performance of the fabricated sample, in which the working in a range of 0.9 GHz–5.2 GHz with the relative bandwidth is 142%, the insertion loss less than 0.5 dB, the reflection coefficient less than −10 dB, and the group delay is less than one ns. This works provides a mirror for realizing the miniaturization of waveguides, and the application and development of high-confinement SSPPs functional devices in the microwave and THz regimes.</jats:p>

<jats:p>We designed a reconfigurable dual-interferometer coupled silicon nitride microring resonator. By tuning the integrated heater on interferometer’s arms, the “critical coupling” bandwidth of resonant mode is continuously adjustable whose quality factor varies from 7.9 × 10<jats:sup>4</jats:sup> to 1.9 × 10<jats:sup>5</jats:sup> with the extinction ratio keeping higher than 25 dB. Also a variety of coupling spanning from “under-coupling” to “over-coupling” were achieved, showing the ability to tune the quality factor from 6.0 × 10<jats:sup>3</jats:sup> to 2.3 × 10<jats:sup>5</jats:sup>. Our design can provide an adjustable filtering method on silicon nitride photonic chip and contribute to optimize the nonlinear process for quantum photonics and all-optical signal processing.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The photonic spin Hall effect (SHE), featured by a spin-dependent transverse shift of left- and right-handed circularly polarized light, holds great potential for applications in optical sensors, precise metrology and nanophotonic devices. In this paper, we present the significant enhancement of photonic SHE in the terahertz range by considering the InSb-supported long-range surface plasmon resonance (LRSPR) effect. The influences of the InSb/ENZ layer thickness and temperature on the photonic SHE were investigated. With the optimal structural parameters and temperature, the maximal spin shift of the horizontal polarization light can reach up to 2.68 mm. Moreover, the spin shift is very sensitive to the refractive index change of gas, and thus a terahertz gas sensing device with a superior intensity sensitivity of 2.5 × 10<jats:sup>5</jats:sup> μm/RIU is proposed. These findings provide an effective method to enhance the photonic SHE in the terahertz range and therefore offer the opportunity for developing the terahertz optical sensors based on photonic SHE.</jats:p>

<jats:p>We propose a simple one-dimensional grating coupling system that can excite multiple surface plasmon resonances for refractive index (RI) sensing with self-reference characteristics in the near-infrared band. Using theoretical analysis and the finite-difference time-domain method, the plasmonic mechanism of the structure is discussed in detail. The results show that the excited resonances are independent of each other and have different fields of action. The mode involving extensive interaction with the analyte environment achieves a high sensitivity of 1236 nm/RIU, and the figure of merit (FOM) can reach 145 RIU<jats:sup>−1</jats:sup>. Importantly, the mode that is insensitive to the analyte environment exhibits good self-reference characteristics. Moreover, we discuss the case of exchanging the substrate material with the analyte environment. Promising simulation results show that this RIsensor can be widely deployed in unstable and complicated environments</jats:p>

<jats:p>We report the fabrication of long period gratings in fluid-cladding microfibers by directly focusing a femtosecond laser beam on the microfibers surface to induce periodical modification a long one side of the microfibers. A long period grating is fabricated in a water-cladding microfiber with a diameter of ~ 5 μm, which demonstrates a resonant attenuation of 28.53 dB at wavelength of 1588.1 nm with 10 pitches. When water cladding is changed to be refractive index oil of <jats:italic>n=</jats:italic> 1.33 and alcohol solution with concentration of 5%, the resonance wavelength shifts to 1575.1 nm with resonant attenuation of 24.91 dB and 1594.1 nm with resonant attenuation of 35.9 dB, respectively. The long period grating demonstrates different temperature sensitivities of–0.524 nm/°C,–0.767 nm/°C and–1.316 nm/°C for water, alcohol solution and refractive index oil cladding microfibers, respectively, which means the alterable liquid cladding allows the availability of tunable wavelength and sensitivity. The fluid-cladding protects the microfibers from external disturbance and contamination and allows more flexibility in controlling the transmission property and sensing characteristics of long period gratings, which can be used as fiber devices and sensors for chemical, biological, and environmental applications.</jats:p>

<jats:p>Topological quantum states have attracted great attention both theoretically and experimentally. Here, we show that the momentum-space lattice allows us to couple two Su–Schrieffer–Heeger (SSH) chains with opposite dimerizations and staggered interleg hoppings. The coupled SSH chain is a four-band model which has sublattice symmetry similar to the SSH4. Interestingly, the topological edge states occupy two sublattices at the same time, which can be regarded as a one-dimension analogue of the type-II corner state. The analytical expressions of the edge states are also obtained by solving the eigenequations. Finally, we provide a possible experimental scheme to detect the topological winding number and corresponding edge states.</jats:p>