arXiv subjects

Xiao-Shuang Li

Publications and source records attributed to Xiao-Shuang Li.

4 recordsLinked to original sources

arXiv2025

Accelerated engineering of topological interface states in one-dimensional phononic crystals via deep learning

Topological interface states (TISs) in phononic crystals (PnCs) are robust acoustic modes against external perturbations, which are of great significance in scientific and engineering communities. However, designing a pair of PnCs with specified band gaps (BGs) and TIS frequency remains a challenging problem. In this work, deep learning (DL) approaches are used for the engineering of one-dimensional (1D) PnCs with high design freedoms. The considered 1D PnCs are composed of periodic solid scatterers embedded in the air background, whose unit cell is divided into a matrix with 32 * 32 pixels. First, the variational autoencoder is applied to reduce the dimensionality of unit cell images, allowing accurate reconstruction of PnC images with different numbers of scatterers. Subsequently, the multilayer perceptron and the tandem neural network are used to realize the property prediction and customized design of 1D PnCs, respectively. The correlation coefficients for the property prediction and inverse design are more than 97%. The unit cell images of 1D PnCs with specific BG properties could be successfully and instantaneously designed. Importantly, the implementation of a "one-to-many" design of PnC pairs with specific TIS frequencies is realized. Furthermore, the reliability and robustness of the constructed networks are confirmed by randomly specifying the design targets as well as the experimental verification. This study demonstrates the broad application prospects of DL approaches in the field of PnC design and provides new ideas and methods for the intelligent design of artificially functional materials.

physics.app-ph↗

arXiv2025

Customizing pseudospin unidirectional states of acoustic and electromagnetic waves in two-dimensional phoxonic topological insulators via multi-objective strategies

Topological materials for classical waves offer remarkable potential in applications such as sensing, waveguiding and signal processing, leveraging topological protection effects like strong robustness, immunity to backscattering and unidirectional transmission. This work presents the simultaneous inverse design of pseudospin-dependent topological edge states for acoustic and electromagnetic waves in two-dimensional $C_{\textrm{6v}}$ phoxonic crystals. The phoxonic crystals are created by arranging the silicon columns periodically in the air background. We propose a multi-objective optimization framework based on the NSGA-II collaborated with the finite element approach, where the bandgaps of acoustic and electromagnetic waves are treated separately as the objective values. The topological nature of bandgaps is determined by analyzing the positional relationships of paired degenerate modes through the modal field calculations, enabling the customization of one of the two bandgaps within the same unit cell. Unlike traditional approaches relying on the band inversion to induce topological phase transitions, the proposed approach directly generates a pair of unit cells with distinct topological properties for both wave types, achieving the maximum bandgap matching in each case. We further demonstrate the existence of the pseudospin-dependent topological edge states for both acoustic and electromagnetic waves, verifying their unidirectionality and robustness against backscattering and defects. This work establishes a systematic strategy for customizing phoxonic topological states, offering a new avenue for the inverse design of multi-functional devices based on both sound and light.

physics.app-ph↗

arXiv2017

Theoretical study on the stimulated Brillouin scattering in a sub-wavelength anisotropic waveguide: Acousto-optical coupling coefficients and effects of transverse anisotropies

A theoretical study on the stimulated Brillouin scattering (SBS) in a sub-wavelength anisotropic waveguide is conducted. The optical, photoelastic and mechanical anisotropies of the waveguide materials are all taken into account. First, the integral formulae for calculating the acousto-optical coupling coefficients (AOCCs) due to the photoelastic and moving interface effects in SBS are extended to an optically anisotropic waveguide. Then, with the extended formulae, the SBSs in an elliptical nanowire with strong transverse anisotropies are simulated. In the simulations, the elastic fields are computed with the inclusion of mechanical anisotropy. Observable effects of the strong transverse anisotropies are found in numerical results. Most notably, the SBS gains of some elastic modes are found to be very sensitive to the small misalignment between the waveguide axes and the principal material axes. Detailed physical interpretations of this interesting phenomenon are provided. This interesting phenomenon implies an attractive way for more sensitive tuning of the SBS gain without significantly changing the phononic frequency.

physics.optics↗

arXiv2017

Heat Reduction by Thermal Wave Crystals

Non-Fourier heat conduction models assume wave-like behavior does exist in the heat conduction process. Based on this wave-like behavior, thermal conduction controlled in a one-dimensional periodical structure, named thermal wave crystal, has been demonstrated through both theoretical analysis and numerical simulation based on the Cattaneo-Vernotte (CV) heat-conduction model. The transfer matrix method and Bloch analysis have been applied to calculate the band structure of thermal wave propagating in thermal wave crystals. And the temperature responses are obtained by using the FDTD method, which is also used to verify the correctness of the band structure. The results show that band gaps do exist due to the Bragg scattering. Then, a calculation method to predict the mid-gap frequency of band gaps for the thermal wave crystal has been introduced in this Letter. And key parameters determining the band gaps have been discussed. This study shows the potential applications of this novel mechanism, such as thermal imagining, thermal diodes and thermal waveguides.

cond-mat.mtrl-sci↗