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Weikang Xu

Publications and source records attributed to Weikang Xu.

4 recordsLinked to original sources

Gene regulatory network inference algorithm based on spectral signed directed graph convolution

Accurately reconstructing Gene Regulatory Networks (GRNs) is crucial for understanding gene functions and disease mechanisms. Single-cell RNA sequencing (scRNA-seq) technology provides vast data for computational GRN reconstruction. Since GRNs are ideally modeled as signed directed graphs to capture activation/inhibition relationships, the most intuitive and reasonable approach is to design feature extractors based on the topological structure of GRNs to extract structural features, then combine them with biological characteristics for research. However, traditional spectral graph convolution struggles with this representation. Thus, we propose MSGRNLink, a novel framework that explicitly models GRNs as signed directed graphs and employs magnetic signed Laplacian convolution. Experiments across simulated and real datasets demonstrate that MSGRNLink outperforms all baseline models in AUROC. Parameter sensitivity analysis and ablation studies confirmed its robustness and the importance of each module. In a bladder cancer case study, MSGRNLink predicted more known edges and edge signs than benchmark models, further validating its biological relevance.

q-bio.MN

Narrow beam and low-sidelobe two-dimensional beam steering on thin-film lithium niobate optical phased array

Optical beam steering has become indispensable in free-space optical communications, light detection and ranging (LiDAR), mapping, and projection. Optical phased array (OPA) leads this field, yet conventional versions still suffer from a narrow steering field of view (FOV), insufficient sidelobe suppression, and limited angular resolution. Thin-film lithium niobate (LN), with its strong Pockels electro-optic (EO) effect, offers a powerful integrated-photonics platform to overcome these limitations. Here we present a two-dimensional (2D) EO-steered OPA based on a non-uniformly spaced X-cut thin-film LN ridge-waveguide array. A superlattice ridge design suppresses optical crosstalk to -20 dB, enabling low-sidelobe far-field radiation. Using particle swarm optimization (PSO) method, we transform a uniformly spaced array into an optimized non-uniform design, largely improving angular resolution while maintaining sidelobe suppression. When combined with a single-radiating trapezoidal end-fire emitter incorporating an etched grating, the device produces a main-lobe beam width of 0.99 degree*0.63 degree from an aperture of only 140 um*250 um, achieving a wide 2D steering range of 47 degree*9.36 degree with a 20 dB sidelobe-suppression ratio. These results highlight thin-film LN OPA as a compelling route toward heterogeneous, compact, and high-performance EO beam-steering modules and ultra-miniaturized optical modulators.

physics.optics

Compact On-Chip crystalline Resonator Integration with Etching Tapered Fiber Waveguide

Whispering-gallery mode crystalline resonators currently maintain the best quality factor (Q) record, however, compact on-chip packaging is still a challenge although various coupling architectures have been developed. Here, a chemical etching method is proposed to fabricate a miniaturized tapered fiber waveguide on silicon substrate. The Marangoni effect is implemented to reduce the surface roughness of the cone region. The optical loss of 0.1 dB/mm is obtained, and the Q of on-chip crystalline resonator exceeds 108. Additionally, TEC is implanted in the package to actively customize the temperature, and the temperature response of 18 pm/K is consistent with the theoretical calculation.

physics.optics

High sensitivity magnetic field sensor via sandwich type PDMS resonator

The sandwich structure as the core layer of PDMS resonator is proposed for single-axis magnetic sensor with high sensitivity. The small Young's modulus of flexible material corresponds to larger variation, resulting in a highly sensitive magnetic response. The sandwich structure pre-set magnetic field provides directional sensing feature. The experimental results show that the redshift sensitivity of 1.08 nm/mT and the blueshift sensitivity of 1.12 nm/mT in the unshielded environment, which is attributed to slight variation in PDMS Young's modulus. At 1.4 kHz, a minimum detectable magnetic field of 0.96 nT Hz-1/2 is realized.

physics.optics