arXiv subjects

Junchao Hu

Publications and source records attributed to Junchao Hu.

3 recordsLinked to original sources

arXiv2026

The Bairong System for MLC-SLM 2026: Dynamic Question-Aware Evidence Routing for Multilingual Conversational Speech Understanding

Long multilingual conversational spoken question answering requires systems to balance long-range transcript semantics with sparse acoustic and speaker-sensitive cues. We present the Bairong system for the MLC-SLM 2026 Challenge, where a diarization-ASR front-end produces speaker-attributed transcripts and a dynamic evidence router constructs question-specific inputs for answer prediction. Instead of applying a fixed transcript-only or audio-only policy, the router infers the required evidence type and context scope from the question and answer options, and selects among full transcript context, local audio-text fusion, speaker-linked evidence, and compact global acoustic samples. This transcript-backbone design keeps discourse context available while activating audio only when it provides complementary evidence. Our Task 1 system achieves 25.70% and 18.44% tcpMER on the development and evaluation sets. For Task 2, the final system obtains 94.84% devel?opment accuracy, outperforming the full-transcript baseline by 1.68 points and the best audio-centric diagnostic system by 2.77 points. These results support dynamic question-aware routing as an effective evidence allocation strategy for conversational spoken QA.

cs.CL↗

arXiv2024

Out-of-plane orientated self-trapped excitons enabled polarized light guiding in 2D perovskites

Active optical waveguides combine light source and waveguides together in an individual component, which are essential for the integrated photonic chips. Although 1D luminescent materials based optical waveguides were extensively investigated, 2D waveguides allow photons to flow within a plane and serve as an ideal component for the ultracompact photonic circuits. Nevertheless, light guiding in 2D planar structures normally relies on the precise control of molecular orientation, which is complicated and low yield. Here, we report a strategy to guide polarized light in 2D microflakes by making use of the out-of-plane (OP) orientation of self-trapped excitons in as-synthesized 2D perovskite microplates. A space confined crystallization method is developed to synthesize 2D perovskite microflakes with dominated broad self-trapped excitons emission at room temperature, which are highly OP orientated with a percentage of the OP component over 85%. Taking advantages of the negligible absorption coefficient and improved coupling efficiency of OP orientated self-trapped exciton emission to the planar waveguide mode of the as-synthesized perovskite microflakes, we have achieved a broadband polarized light guiding with a full width at half maximum over 120 nm. Our findings provide a promising platform for the development of ultracompact photonic circuits.

physics.optics↗

arXiv2022

Efficient electrical switching of exciton states for valley contrast manipulation in two-dimensional perovskite/monolayer WS2 heterostructures

The coupled spin-valley physics in transition metal dichalcogenides (TMDs) endows exciton states with valley degrees of freedom, making them promising for valleytronic applications in TMDs monolayers and/or their heterostructures. Although the valley dynamics of intralayer and interlayer excitons (IXs) have been studied, efficient manipulation of valley pseudospins by switching exciton states remains elusive. Therefore, it is of great importance to effectively tune the exciton states to obtain practical valley polarization switches for valley encoding. Here, we demonstrate the electrical switching of exciton emission with highly variable valley polarization mediated by charged IXs (CIXs) in the heterostructure of monolayer WS2 and two-dimensional (2D) perovskite, irrespective of lattice constants, the rotational and translational alignment. The formation of IXs is identified by photoluminescence excitation (PLE) and photoluminescence (PL) studies, which can be further electrically tuned from positively charged to negatively charged depending on the electrostatic doping level of monolayer WS2. Importantly, we demonstrate an electrical switching from type two to type one band alignment, manifesting as a change in the PL profile from CIX to charged intralayer exciton emission. Such transition induces a large contrast in valley polarization between the two exciton states, enabling the reversible electrically regulated valley polarization switch with a maximum ON/OFF ratio of 15.8. Our study provides an alternative mechanism to achieve valley polarization switching with great simplicity for valleytronics and the electrical control of exciton species and associated valley-contrasting physics would further facilitate the development of optoelectronic and valleytronic devices

physics.app-ph↗