arXiv subjects

Chuntao Li

Publications and source records attributed to Chuntao Li.

At least 19 recordsLinked to original sources

arXiv2026

Specializing Large Models for Oracle Bone Script Interpretation via Component-Grounded Multimodal Knowledge Augmentation

Deciphering ancient Chinese Oracle Bone Script (OBS) is a challenging task that offers insights into the beliefs, systems, and culture of the ancient era. Existing approaches treat decipherment as a closed-set image recognition problem, which fails to bridge the ``interpretation gap'': while individual characters are often unique and rare, they are composed of a limited set of recurring, pictographic components that carry transferable semantic meanings. To leverage this structural logic, we propose an agent-driven Vision-Language Model (VLM) framework that integrates a VLM for precise visual grounding with an LLM-based agent to automate a reasoning chain of component identification, graph-based knowledge retrieval, and relationship inference for linguistically accurate interpretation. To support this, we also introduce OB-Radix, an expert-annotated dataset providing structural and semantic data absent from prior corpora, comprising 1,022 character images (934 unique characters) and 1,853 fine-grained component images across 478 distinct components with verified explanations. By evaluating our system across three benchmarks of different tasks, we demonstrate that our framework yields more detailed and precise decipherments compared to baseline methods.

cs.CV↗

arXiv2026

Highly-efficient, narrow-linewidth Brillouin microlasers implemented in compact thin-film lithium niobate microresonators

Stimulated Brillouin microlasers offer chip-scale light sources with high spectral purity and low phase noise--key attributes for applications spanning precision metrology, quantum technologies, and coherent information processing. However, simultaneously bringing both pump and scattered waves into resonance often compromises photon confinement or modal volume, resulting in limited conversion efficiency and elevated thresholds. In this work, a novel approach is proposed to generate Brillouin microlasers with high efficiency, low threshold, and narrow linewidth, by combining a cross-polarized stimulated Brillouin scattering scheme with intentional Stokes mode splitting to compensate for mode detuning. Triple-resonance and phase-matching conditions are simultaneously achieved in a 114-um-diameter thin-film lithium niobate (TFLN) microresonator, enabling precise alignment with both the ~10-GHz Brillouin shift and the ~100-MHz narrow gain bandwidth. The resulting Brillouin microlaser achieves a narrow intrinsic linewidth of 2.88 Hz, a short-term integral linewidth of 185 Hz, an on-chip conversion efficiency of 57.92%, and a pump threshold as low as 1.03 mW. Both the conversion efficiency and the lasing threshold represent record-high performance for the TFLN platform to date.

physics.optics↗

arXiv2025

Highly efficient multi-chromatic Raman microlasers from cavity polygon modes on thin-film lithium niobate platform

The integration of stimulated Raman scattering (SRS) and second order nonlinearity in non-centrosymmetric photonic microresonators presents a highly promising solution for developing on-chip coherent light sources with exceptional bandwidth and flexible tunability. Our study introduces an innovative methodology leveraging cavity polygon modes within an X-cut thin-film lithium niobate microdisk to achieve highly efficient multi-chromatic Raman microlasers. Specifically, high-Q square modes characterized by two parallel sides oriented perpendicularly relative to the optical axis of lithium niobate crystal were excited. These modes offer distinct advantages, including enhancing both mode-field overlap and improved phase matching, achieved through the utilization of the largest second-order susceptibility component (d_33), which is critical for Raman-quadratic nonlinear interactions. The experimental results highlight significant advancements in multi-wavelength multi-wavelength laser generation, with forward stimulated Raman laser signals exhibiting a high conversion efficiency of up to 65.02% and an impressively narrow integral linewidth of only 5.2 kHz. Simultaneously, our system enables the generation of multi-wavelength Raman-quadratic laser signals across the ~800 nm and ~530 nm spectral bands. These findings are further underscored by an impressive absolute conversion efficiency of 1.33% for the 797.4-nm Raman laser, achieved at a remarkably low pump power of just 1.07 mW. This work not only extends the application scope of cavity polygon modes from single second/third-order nonlinear optical processes to cascaded processes but also establishes a foundation for realizing high-efficiency on-chip multi-chromatic laser sources with versatile functionalities.

physics.optics↗

arXiv2025

Simultaneous generation of Raman-assisted Soliton Microcombs and Tunable Multi-chromatic Raman Microlasers in Single Monolithic Thin-film Lithium Niobate Microrings

High-performance integrated broadband coherent light sources are essential for advanced applications in high-bandwidth data processing and chip-scale metrology, yet remain challenging. In this study, we demonstrate a monolithic Z-cut lithium niobate on insulator (LNOI) microring platform that enables simultaneous generation of tunable multi-chromatic microlasers and Raman-assisted soliton microcombs. Exploiting the strong Raman activity and high second-order nonlinearity of LNOI, we engineered a dispersion-optimized microring with a loaded Q factor of 3.86X10^6, facilitating on-chip efficient broadband coherent light source. A novel phase-matching configuration with all the waves of the same ordinary polarization was realized for the first time in this platform, feasibly enabling modal-phase matched Raman-quadratic nonlinear processes that extend lasing signals into the visible spectrum. Under continuous-wave laser pumping at 3.73 mW in the telecom band, we achieved a Raman-assisted soliton comb centered at 1624.49 nm with record-low pump threshold on the LNOI platform. Concurrently, multi-chromatic Raman lasing outputs were observed at ~1700, ~813, and ~535 nm within the same microring. The system exhibited efficient wavelength tuning of these multi-chromatic laser signals through a 5 nm shift in pump wavelength. This work represents a significant advance in integrated photonics for versatile optical signal generation.

physics.optics↗

arXiv2025

LadderMoE: Ladder-Side Mixture of Experts Adapters for Bronze Inscription Recognition

Bronze inscriptions (BI), engraved on ritual vessels, constitute a crucial stage of early Chinese writing and provide indispensable evidence for archaeological and historical studies. However, automatic BI recognition remains difficult due to severe visual degradation, multi-domain variability across photographs, rubbings, and tracings, and an extremely long-tailed character distribution. To address these challenges, we curate a large-scale BI dataset comprising 22454 full-page images and 198598 annotated characters spanning 6658 unique categories, enabling robust cross-domain evaluation. Building on this resource, we develop a two-stage detection-recognition pipeline that first localizes inscriptions and then transcribes individual characters. To handle heterogeneous domains and rare classes, we equip the pipeline with LadderMoE, which augments a pretrained CLIP encoder with ladder-style MoE adapters, enabling dynamic expert specialization and stronger robustness. Comprehensive experiments on single-character and full-page recognition tasks demonstrate that our method substantially outperforms state-of-the-art scene text recognition baselines, achieving superior accuracy across head, mid, and tail categories as well as all acquisition modalities. These results establish a strong foundation for bronze inscription recognition and downstream archaeological analysis.

cs.CV↗

arXiv2025

Clustering-based Feature Representation Learning for Oracle Bone Inscriptions Detection

Oracle Bone Inscriptions (OBIs), play a crucial role in understanding ancient Chinese civilization. The automated detection of OBIs from rubbing images represents a fundamental yet challenging task in digital archaeology, primarily due to various degradation factors including noise and cracks that limit the effectiveness of conventional detection networks. To address these challenges, we propose a novel clustering-based feature space representation learning method. Our approach uniquely leverages the Oracle Bones Character (OBC) font library dataset as prior knowledge to enhance feature extraction in the detection network through clustering-based representation learning. The method incorporates a specialized loss function derived from clustering results to optimize feature representation, which is then integrated into the total network loss. We validate the effectiveness of our method by conducting experiments on two OBIs detection dataset using three mainstream detection frameworks: Faster R-CNN, DETR, and Sparse R-CNN. Through extensive experimentation, all frameworks demonstrate significant performance improvements.

cs.CV↗

arXiv2025

Ancient Script Image Recognition and Processing: A Review

Ancient scripts, e.g., Egyptian hieroglyphs, Oracle Bone Inscriptions, and Ancient Greek inscriptions, serve as vital carriers of human civilization, embedding invaluable historical and cultural information. Automating ancient script image recognition has gained importance, enabling large-scale interpretation and advancing research in archaeology and digital humanities. With the rise of deep learning, this field has progressed rapidly, with numerous script-specific datasets and models proposed. While these scripts vary widely, spanning phonographic systems with limited glyphs to logographic systems with thousands of complex symbols, they share common challenges and methodological overlaps. Moreover, ancient scripts face unique challenges, including imbalanced data distribution and image degradation, which have driven the development of various dedicated methods. This survey provides a comprehensive review of ancient script image recognition methods. We begin by categorizing existing studies based on script types and analyzing respective recognition methods, highlighting both their differences and shared strategies. We then focus on challenges unique to ancient scripts, systematically examining their impact and reviewing recent solutions, including few-shot learning and noise-robust techniques. Finally, we summarize current limitations and outline promising future directions. Our goal is to offer a structured, forward-looking perspective to support ongoing advancements in the recognition, interpretation, and decipherment of ancient scripts.

cs.CV↗

arXiv2025

Visible Brillouin-quadratic microlaser in a high-Q thin-film lithium niobate microdisk

Narrow-linewidth lasers at short/visible wavelengths are crucial for quantum and atomic applications, such as atomic clocks, quantum computing, atomic and molecular spectroscopy, and quantum sensing. However, such lasers are often only accessible in bulky tabletop systems and remain scarce in integrated photonic platform. Here, we report an on-chip visible Brillouin-quadratic microlaser in a 117-um-diameter thin-film lithium niobate (TFLN) microdisk via dispersion engineering. Enabled by the ultra-high Q factor of 4.0X10(6) and small mode volume, strong photon-phonon interaction and high second-order nonlinearity of the TFLN microdisk, narrow-linewidth Stokes Brillouin lasing (SBL) is demonstrated with 10.17 GHz Brillouin shift under a 1560-nm pump, exhibiting a short-term narrow linewidth of 254 Hz and a low threshold of only 1.81 mW. Meanwhile, efficient second harmonic generation (SHG) of the SBL signal is also observed at 780 nm, with a normalized conversion efficiency of 3.61%/mW, made possible by simultaneous phase matching fulfillments for both narrow-linewidth SBL and its SHG. This demonstration of an integrated ultra-narrow linewidth visible wavelength Brillouin-quadratic lasers opens new avenues toward chip-scale quantum information processing and precise metrology.

physics.optics↗

arXiv2025

Low-loss thin-film periodically poled lithium niobate waveguides fabricated by femtosecond laser photolithography

Periodically poled lithium niobate on insulator (PPLNOI) ridge waveguides are critical photonic components for both classical and quantum information processing. However, dry etching of PPLNOI waveguides often generates rough sidewalls and variations in the etching rates of oppositely poled lithium niobate ferroelectric domains, leading a relatively high propagation losses (0.25 - 1 dB/cm), which significantly limits net conversion efficiency and hinders scalable photonic integration. In this work, a low-loss PPLNOI ridge waveguide with a length of 7 mm was fabricated using ultra-smooth sidewalls through photolithography-assisted chemo-mechanical etching (PLACE) followed by high-voltage pulse poling with low cost. The average surface roughness was measured at just 0.27 nm, resulting in record-low propagation loss of 0.106 dB/cm in PPLNOI waveguides. Highly efficient second-harmonic generation was demonstrated with a normalized efficiency of 1643%/(W*cm^2) without temperature tuning, corresponding to a conversion efficiency of 805%/W, which is closed to the best conversion efficiency (i.e., 814%/W) reported in nanophotonic PPLNOI waveguide fabricated by expensive electron-beam lithography followed by dry etching. The absolute conversion efficiency reached 15.8% at a pump level of 21.6 mW. And the normalized efficiency can be even improved to 1742%/(W*cm^2) at optimal temperature of 59{\deg}C.

physics.optics↗

arXiv2025

Simultaneously generating Brillouin microlaser and second harmonic within a lithium niobate microdisk

We report the simultaneous generation of second-harmonic generation (SHG) and Brillouin microlaser in a high-quality thin-film lithium niobate (TFLN) microdisk resonator. The microdisk is fabricated with ultrahigh-Q factor of 4X10(6) by photolithography-assisted chemo-mechanical etching, enabling significant cavity-enhancement effect for boosting nonlinear frequency conversion. Under 1559.632 nm pumping, Brillouin microlaser is demonstrated in the microdisk with Stokes Brillouin shift of 10 GHz, a low threshold of 1.81 mW, and a fundamental linewidth of 254.365 Hz. Meanwhile, efficient SHG is observed at 779.816 nm with an absolute conversion efficiency of 3.8% at pump level of 3.028 mW. The coexistence of these two nonlinear processes is enabled by the simultaneous confinement of the light and acoustic fileds for effect coupling in the microdisk, which enhances both optomechanical and second-order nonlinear interactions. This research provides new possibilities for integrated multi-frequency laser sources and multifunctional nonlinear photonic devices.

physics.optics↗

arXiv2024

ShiftedBronzes: Benchmarking and Analysis of Domain Fine-Grained Classification in Open-World Settings

In real-world applications across specialized domains, addressing complex out-of-distribution (OOD) challenges is a common and significant concern. In this study, we concentrate on the task of fine-grained bronze ware dating, a critical aspect in the study of ancient Chinese history, and developed a benchmark dataset named ShiftedBronzes. By extensively expanding the bronze Ding dataset, ShiftedBronzes incorporates two types of bronze ware data and seven types of OOD data, which exhibit distribution shifts commonly encountered in bronze ware dating scenarios. We conduct benchmarking experiments on ShiftedBronzes and five commonly used general OOD datasets, employing a variety of widely adopted post-hoc, pre-trained Vision Large Model (VLM)-based and generation-based OOD detection methods. Through analysis of the experimental results, we validate previous conclusions regarding post-hoc, VLM-based, and generation-based methods, while also highlighting their distinct behaviors on specialized datasets. These findings underscore the unique challenges of applying general OOD detection methods to domain-specific tasks such as bronze ware dating. We hope that the ShiftedBronzes benchmark provides valuable insights into both the field of bronze ware dating and the and the development of OOD detection methods. The dataset and associated code will be available later.

cs.CV↗

arXiv2024

LineArt: A Knowledge-guided Training-free High-quality Appearance Transfer for Design Drawing with Diffusion Model

Image rendering from line drawings is vital in design and image generation technologies reduce costs, yet professional line drawings demand preserving complex details. Text prompts struggle with accuracy, and image translation struggles with consistency and fine-grained control. We present LineArt, a framework that transfers complex appearance onto detailed design drawings, facilitating design and artistic creation. It generates high-fidelity appearance while preserving structural accuracy by simulating hierarchical visual cognition and integrating human artistic experience to guide the diffusion process. LineArt overcomes the limitations of current methods in terms of difficulty in fine-grained control and style degradation in design drawings. It requires no precise 3D modeling, physical property specs, or network training, making it more convenient for design tasks. LineArt consists of two stages: a multi-frequency lines fusion module to supplement the input design drawing with detailed structural information and a two-part painting process for Base Layer Shaping and Surface Layer Coloring. We also present a new design drawing dataset ProLines for evaluation. The experiments show that LineArt performs better in accuracy, realism, and material precision compared to SOTAs.

cs.CV↗

arXiv2024

Second harmonic generation with 48% conversion efficiency from cavity polygon modes in a monocrystalline lithium niobate microdisk resonator

Thin-film lithium niobate (TFLN) based optical microresonators offer large nonlinear coefficient d_33 and high light-wave confinement, allowing highly efficient second-order optical nonlinear frequency conversion. Here, we achieved ultra-efficiency second harmonic generation (SHG) from high-Q polygon modes by maximizing the utilization of the highest nonlinear coefficient d_33 in a monocrystalline X-cut TFLN microdisk resonator for the first time. The polygon modes are designed and formed with two parallel sides perpendicular to the optical axis of the lithium niobate crystal by introducing weak perturbations into the microdisk of a tapered fiber, which maximizes the utilization of d_33. The polygon modes exhibit ultrahigh intrinsic Q factors of ~3.86X10(7), due to the fact that polygon modes are located far from the relatively rough sidewall of the microdisk. Moreover, the pump and second harmonic polygon modes share high modal overlap factor of ~80%. Consequently, SHG from cavity polygon modes with absolute conversion efficiency as high as 48.08% was realized at an on-chip pump level of only 4.599 mW without fine domain structures, surpassing the best results (23% and 30%) reported in other two domain-inversion-free phase matching schemes and even approaching the record (52%) in PPLN microresonators.

physics.optics↗

arXiv2024

On-chip electro-optically tunable narrow linewidth Brillouin microlasers implemented in thin film lithium niobate

On-chip narrow linewidth microlasers with real-time wavelength tunability are highly desirable for various applications including precision metrology, quantum technology, and coherent information processing. Realizing such laser remains a challenge despite significant advances made by various groups in recent years [Nat. Commun. 13, 5344 (2022); Nature 615, 411 (2023); Appl. Phys. Lett. 124, 131101 (2024); Nat. Photonics 13, 60 (2019)]. In this work, we overcome these hurdles and demonstrate on-chip electro-optically tunable Brillouin microlasers in compact lithium niobate on insulator (LNOI) microdisks with diameters of 31.5 um and 117.0 um by using cross-polarized SBS arrangement. A quasi-continuum band of bound shear mechanical modes inside the suspended microdisk are revealed for the first time, allowing feasible phase matching of stimulated Brillouin lasing (SBL). We achieve efficient cross-polarized optomechanical coupling and SBL via the significant photoelastic tensors of lithium niobate (e.g., p41=-1.51). This approach yields a 118 Hz intrinsic linewidth and a comparatively low threshold power of 3.15 mW. A real-time electro-optic tuning of the cross-polarized Brillouin scheme with a tuning efficiency of ~93.1 kHz/V is also achieved, further showcasing potential of LNOI platform for next-generation tunable photonic systems.

physics.optics↗

arXiv2024

Gamification of virtual museum curation: a case study of Chinese bronze wares

Museums, which are among the most popular science institutions outside schools, are usually used to display and introduce historical culture and cultural relics to tourists. Text and audio explanations are used by traditional museums to popularize historical knowledge and science for tourists, and general interactive systems are based on desktops. This learning method is relatively boring in terms of experience. As a result, tourists have no desire or interest in actively exploring and learning about bronze ware, so they only have a basic understanding about bronze ware. Since most tourists are familiar with games, they are more likely to be attracted by game content and will actively explore and interact with it. In addition, a certain degree of reality is created by virtual reality technology and an immersive experience through head-mounted devices is provided to users. In this paper, we take Chinese bronzes as the research objects. We first use laser scanners to obtain bronze models ; then, we build a virtual museum environment, and we finally design a virtual reality curation game based on this bronze digital museum. This game offers visitors an immersive museum roaming and bronze ware interactive experience. Through a combination of text, video learning, and games, visitors' curiosity and desire to explore bronze ware are stimulated, and their understanding and ability to remember bronze ware knowledge can be deepened. In terms of cultural heritage, this game is also conducive to the spread of traditional Chinese bronze culture throughout the world.

cs.CY↗

arXiv2024

Efficient transverse multi-wave interactions up to six-wave mixing in a high-Q lithium niobate microresonator

High-order nonlinear optical processes beyond four-wave mixing serve as fundamental tools for advancing photonic technologies, yet their practical implementation remains challenging due to stringent phase-matching requirements and inherently weak high-order nonlinear susceptibilities - limitations that persist even in state-of-the-art high-Q microresonators. In this work, we demonstrate a breakthrough in synthesizing transverse nonlinear processes up to six-wave mixing in an integrated lithium niobate microresonator, under single continuous-wave (CW) telecom-band laser pump. Our approach leverages self-organized subwavelength photorefractive gratings (SPGs) generated through bidirectional stimulated Raman scattering (SRS) process in the microresonator, without using two external counterpropagating lasers. Under 1546 nm pumping, bidirectional SRS at 1713 nm creates two counterpropagating light waves that spontaneously form SPGs. These SPGs critically enable broadband phase-matching compensation across 500 nm spectral range by providing additional momentum matching for transverse nonlinear processes while maintaining ultrahigh-Q factor. Moreover, cascaded SRS process is simultaneously activated to generate light signal for subsequent nonlinear interactions. This novel approach enables, to our knowledge, the first demonstration of single-pump phase-matched transverse sum-frequency generation (SFG) with record conversion efficiency (590%/W). Furthermore, transverse multi-wave mixing processes from four-wave to six-wave mixing processes are achieved with high conversion efficiencies for the first time using only the single CW pump, representing a notable advance in nonlinear integration.

physics.optics↗

arXiv2024

FilterPrompt: A Simple yet Efficient Approach to Guide Image Appearance Transfer in Diffusion Models

In controllable generation tasks, flexibly manipulating the generated images to attain a desired appearance or structure based on a single input image cue remains a critical and longstanding challenge. Achieving this requires the effective decoupling of key attributes within the input image data to achieve representations accurately. Previous works have concentrated predominantly on disentangling image attributes within feature space. However, the complex distribution present in real-world data often makes the application of such decoupling algorithms to other datasets challenging. Moreover, the granularity of control over feature encoding frequently fails to meet specific task requirements. Upon scrutinizing the characteristics of various generative models, we have observed that the input sensitivity and dynamic evolution properties of the diffusion model can be effectively fused with the explicit decomposition operation in pixel space. This allows the operation that we design and use in pixel space to achieve the desired control effect on the specific representation in the generated results. Therefore, we propose FilterPrompt, an approach to enhance the effect of controllable generation. It can be universally applied to any diffusion model, allowing users to adjust the representation of specific image features in accordance with task requirements, thereby facilitating more precise and controllable generation outcomes. In particular, our designed experiments demonstrate that the FilterPrompt optimizes feature correlation, mitigates content conflicts during the generation process, and enhances the effect of controllable generation.

cs.CV↗

arXiv2023

Integrated multi-color Raman microlasers with ultra-low pump levels in single high-Q lithium niobate microdisks

Photonic integrated Raman microlasers, particularly discrete multi-color lasers which are crucial for extending the emission wavelength range of chip-scale laser sources to much shorter wavelength, are highly in demand for various spectroscopy, microscopy analysis, and biological detection. However, integrated multi-color Raman microlasers have yet to be demonstrated because of the requirement of high-Q microresonators possessing large second-order nonlinearity and strong Raman phonon branches and the challenging in cavity-enhanced multi-photon hyper-Raman scattering parametric process. In this work, integrated multi-color Raman lasers have been demonstrated for the first time at weak pump levels, via the excitation of high-Q (>6 X 10^6) phase-matched modes in single thin-film lithium niobate (TFLN) microresonators by dispersion engineering. Raman lasing was observed at 1712 nm for a 1546-nm pump threshold power of only 620 uW. Furthermore, multi-color Raman lasers were realized at discrete wavelengths of 1712 nm, 813 nm, 533 nm and 406 nm with pump levels as low as 1.60 mW, which is more than two order of magnitude lower than the current records (i.e., 200 mW) in bulk resonators, allowed by the fulfillment of the requisite conditions consisting of broadband natural phase match, multiple-resonance and high Q-factors.

physics.optics↗