arXiv subjects

Huijie Li

Publications and source records attributed to Huijie Li.

5 recordsLinked to original sources

arXiv2026

Low-threshold vortex lasing in three-dimensional cavities via flatband bound states in the continuum

Bound states in the continuum (BICs) offer a robust route toward high-Q resonators and topological structured-light generation. While optically pumped BIC lasers have advanced significantly, realizing electrically pumped vortex lasers remains challenging due to conflicting requirements for optical confinement and carrier injection. Here, we demonstrate an electrically pumped vector vortex laser based on a photonic crystal-guiding layer-distributed Bragg reflector (PC-GL-DBR) heterostructure. The photonic crystal slab precisely tailors the symmetry and dispersion of BIC modes, including a flatband BIC state, while an intermediate guiding layer enables optical mode engineering without directly patterning the multiple-quantum-well active region, preserving efficient carrier injection and strong optical confinement. Under optical pumping, the device achieves single-mode lasing with a Q of 9700, a threshold of 0.129 kW/cm$^2$, and a side-mode suppression ratio of 26 dB. Crucially, room-temperature electrically pumped vortex lasing is achieved with a low turn-on voltage of 1.8 V, a threshold current density of 0.13 kA/cm$^2$, and a cavity Q of 8600, successfully preserving the characteristic vector-vortex emission of the topological BIC state. These results establish a practical route toward electrically driven BIC vortex lasers for integrated structured-light sources and topological photonics.

physics.optics↗

arXiv2025

Multi-Agent Deep Reinforcement Learning for Multiple Anesthetics Collaborative Control

Automated control of personalized multiple anesthetics in clinical Total Intravenous Anesthesia (TIVA) is crucial yet challenging. Current systems, including target-controlled infusion (TCI) and closed-loop systems, either rely on relatively static pharmacokinetic/pharmacodynamic (PK/PD) models or focus on single anesthetic control, limiting personalization and collaborative control. To address these issues, we propose a novel framework, Value Decomposition Multi-Agent Deep Reinforcement Learning (VD-MADRL). VD-MADRL optimizes the collaboration between two anesthetics propofol (Agent I) and remifentanil (Agent II). And It uses a Markov Game (MG) to identify optimal actions among heterogeneous agents. We employ various value function decomposition methods to resolve the credit allocation problem and enhance collaborative control. We also introduce a multivariate environment model based on random forest (RF) for anesthesia state simulation. Additionally, a data resampling and alignment technique ensures synchronized trajectory data. Our experiments on general and thoracic surgery datasets show that VD-MADRL performs better than human experience. It improves dose precision and keeps anesthesia states stable, providing great clinical value.

eess.SY↗

arXiv2024

A Model-free Biomimetics Algorithm for Deterministic Partially Observable Markov Decision Process

Partially Observable Markov Decision Process (POMDP) is a mathematical framework for modeling decision-making under uncertainty, where the agent's observations are incomplete and the underlying system dynamics are probabilistic. Solving the POMDP problem within the model-free paradigm is challenging for agents due to the inherent difficulty in accurately identifying and distinguishing between states and observations. We define such a difficult problem as a DETerministic Partially Observable Markov Decision Process (DET-POMDP) problem, which is a specific setting of POMDP. In this problem, states and observations are in a many-to-one relationship. The state is obscured, and its relationship is less apparent to the agent. This creates obstacles for the agent to infer the state through observations. To effectively address this problem, we convert DET-POMDP into a fully observable MDP using a model-free biomimetics algorithm called BIOMAP. BIOMAP is based on the MDP Graph Automaton framework to distinguish authentic environmental information from fraudulent data. Thus, it enhances the agent's ability to develop stable policies against DET-POMDP. The experimental results highlight the superior capabilities of BIOMAP in maintaining operational effectiveness and environmental reparability in the presence of environmental deceptions when compared with existing POMDP solvers. This research opens up new avenues for the deployment of reliable POMDP-based systems in fields that are particularly susceptible to DET-POMDP problems.

eess.SY↗

arXiv2022

A phase transition driven by subtle distortion without broken symmetry on spin, charge and lattice in Layered LnCu4-δP2(Ln=Eu, Sr)

In the scenario of Landau phase transition theory in condensed matter physics, any thermal dynamic phase transition must be subject to some kind of broken symmetries, that are relative to its spin, charge, orbital and lattice. Here we report a rare phase transition at Tp ~120 K or 140 K in layered materials LnCu4-δP2 (Ln=Eu, Sr) driven by a subtle structural-distortion without any broken symmetry on charge, spin and lattice. The variations of the lattice parameters, (ΔLc/Lc) ~ 0.013% or 0.062%, verified by thermal expansion, is much less than that for a typical crystalline phase transition (~0.5-1%), but the significant anomaly in heat capacity provides clear evidence of its intrinsic nature of thermodynamic transition.

cond-mat.str-el↗

arXiv2021

Unusual Magnetic Properties in Layered Magnetic Topological Insulator EuSn2As2

EuSn2As2 with layered rhombohedral crystal structure is proposed to be a candidate of intrinsic antiferromagnetic (AFM) topological insulator. Here, we have investigated systematic magnetoresistance (MR) and magnetization measurements on the high quality EuSn2As2 single crystal with the magnetic field both parallel and perpendicular to (00l) plane. Both the kink of magnetic susceptibility and longitudinal resistivity reveal that EuSn2An2 undergoes an AFM transition at TN = 21 K. At T = 2 K, the magnetization exhibits two successive plateaus of ~ 5.6 μB/Eu and ~ 6.6 μB/Eu at the corresponding critical magnetic fields. Combined with the negative longitudinal MR and abnormal Hall resistance, we demonstrate that EuSn2An2 undergoes complicated magnetic transitions from an AFM state to a canted ferromagnetic (FM) state at Hc and then to a polarized FM state at Hs as the magnetic field increase.

cond-mat.mtrl-sci↗