arXiv subjects

Minglie Hu

Publications and source records attributed to Minglie Hu.

11 recordsLinked to original sources

arXiv2026

Probing Internal Dynamics of Spatiotemporal Optical Vortex Strings: Spatiotemporal Attraction and Filament Stretching

Vortex dynamics are intriguing and challenging across multiple physics fields. In optics, customized spatiotemporally structured optical fields, especially spatiotemporal optical vortices (STOV), offer the potential to tailor light via coupled space-time degrees of freedom. However, the interaction mechanisms between multiple transverse orbital angular momentum singularities within a single wave packet remain elusive. This study explores the intrinsic dynamics of a STOV with three phase singularities, observing a pronounced vortex singularity oscillation phenomena by tuning the temporal dispersion. We show that these phenomena originate from the counterintuitive spatiotemporal attractive effect between vortices, which is closely related to the singularity distance. Furthermore, the stretching into filaments and annihilation behaviors is observed by introducing antivortex in the center of the wavepacket. Experimentally, we propose a Full Interferometric Retrieval of Spatiotemporal Tomography (FIRST) method that enables the complete, single-shot capture of wave packets, with excellent agreement between theoretical predictions and experimental results. To the best of our knowledge, the dynamics of transverse spatiotemporal singularities within a single wave packet are reported here for the first time. These findings confirm the existence of interesting interactions between STOV singularities, deepen our understanding of photonics and open a new direction for investigating the complex dynamics of vortex singularities in the spatiotemporal domain.

physics.optics↗

arXiv2025

A versatile coherent Ising computing platform

Coherent Ising Machines (CIMs) have emerged as a hybrid form of quantum computing devices designed to solve NP-complete problems, offering an exciting opportunity for discovering optimal solutions. Despite challenges such as susceptibility to noise-induced local minima, we achieved notable advantages in improving the computational accuracy and stability of CIMs. We conducted a successful experimental demonstration of CIM via femto-second laser pumping that integrates optimization strategies across optical and structural dimensions, resulting in significant performance enhancements. The results are particularly promising. An average success rate of 55% was achieved to identify optimal solutions within a Mobius Ladder graph comprising 100 vertices. Compared with other alternatives, the femto-second pulse results in significantly higher peak power, leading to more pronounced quantum effects and lower pump power in optical fiber based CIMs. In addition, we have maintained an impressive success rate for a continuous period of 8 hours, emphasizing the practical applicability of CIMs in real-world scenarios. Furthermore, our research extends to the application of these principles in practical applications such as molecular docking and credit scoring. The results presented substantiate the theoretical promise of CIMs, paving the way for their integration into large-scale practical applications.

quant-ph↗

arXiv2024

Bose-Einstein condensation of an optical thermodynamic system into a solitonic state

Recent years have seen a resurgence of interest in multimode fibers due to their intriguing physics and applications, with spatial beam self-cleaning (BSC) having received special attention. In BSC light condenses into the fundamental fiber mode at elevated intensities. Despite extensive efforts utilizing optical thermodynamics to explain such counterintuitive beam reshaping process, several challenges still remain in fully understanding underlying physics. Here we provide compelling experimental evidence that BSC in a dissipative dual-core fiber can be understood in full analogy to Bose-Einstein condensation (BEC) in dilute gases. Being ruled by the identical Gross-Pitaevskii Equation, both systems feature a Townes soliton solution, for which we find further evidence by modal decomposition of our experimental data. Specifically, we observe that efficient BSC only sets in after an initial thermalization phase, causing converge towards a Townes beam profile once a threshold intensity has been surpassed. This process is akin to a transition from classical to quantum-mechanical thermodynamics in BEC. Furthermore, our analysis also identifies dissipative processes as a crucial, yet previously unidentified component for efficient BSC in multimode fiber. This discovery paves the way for unprecedented applications of multimode-fiber based systems in ultrafast lasers, communications, and fiber-based delivery of high-power laser beams.

physics.optics↗

arXiv2022

Fast predicting the complex nonlinear dynamics of mode-locked fiber laser by a recurrent neural network with prior information feeding

As an imperative method of investigating the internal mechanism of femtosecond lasers, traditional femtosecond laser modeling relies on the split-step Fourier method (SSFM) to iteratively resolve the nonlinear Schrodinger equation suffering from the large computation complexity. To realize inverse design and optimization of femtosecond lasers, numerous simulations of mode-locked fiber lasers with different cavity settings are required further highlighting the time-consuming problem induced by the large computation complexity. Here, a recurrent neural network is proposed to realize fast and accurate femtosecond mode-locked fiber laser modeling for the first time. The generalization over different cavity settings is achieved via our proposed prior information feeding method. With the acceleration of GPU, the mean time of the artificial intelligence (AI) model inferring 500 roundtrips is less than 0.1 s. Even on an identical CPU-based hardware platform, the AI model is still 6 times faster than the SSFM method. The proposed AI-enabled method is promising to become a standard approach to femtosecond laser modeling.

physics.optics↗

arXiv2022

Collision-induced Hopf-type bifurcation reversible transitions in a dual-wavelength femtosecond fiber laser

Collision refers to a striking nonlinear interaction in dissipative systems, revealing the particle-like properties of solitons. In dual-wavelength mode-locked fiber lasers, collisions are inherent and periodic. However, how collisions influence the dynamical transitions in the dual-wavelength mode-locked state has still not been explored. In our research, dispersion management triggers the complex interactions between solitons in the cavity. We reveal the smooth or reversible Hopf-type bifurcation transitions of dual-color soliton molecules (SMs) during collision by real-time spectral measurement technique of TS-DFT. The reversible transitions from stationary SM to vibrating SM, revealing that cavity parameters pass through a bifurcation point in the collision process without active external intervention. The numerical results confirm the universality of collision-induced bifurcation behavior. These findings provide new insights into collision dynamics in dual-wavelength ultrafast fiber lasers. Furthermore, the study of intermolecular collisions is of great significance for other branches of nonlinear science.

physics.optics↗

arXiv2022

Chaotic internal dynamics of dissipative optical soliton molecules

When a laser cavity supports the propagation of several ultrashort pulses, these pulses interact and can form compact bound states called soliton molecules. Soliton molecules are fascinating objects of nonlinear science, which present striking analogies with their matter molecules counterparts. The soliton pair, composed of two identical pulses, constitutes the chief soliton molecule of fundamental interest. The relative timing and phase between the two propagating pulses are the most salient internal degrees of freedom of the soliton molecule. These two internal degrees of freedom allow self-oscillating soliton molecules, which have indeed been repeatedly observed, whereas the lowdimensional chaotic dynamics of a soliton-pair molecule remains elusive, noting that it would require at least three degrees of freedom. We here report the observation of chaotic soliton-pair molecules within an ultrafast fiber laser, by means of a direct measurement of the relative optical pulse separation with sub-femtosecond precision in real time. Moreover, we demonstrate an all-optical control of the chaotic dynamics followed by the soliton molecule, by injecting a modulated optical signal that resynchronizes the internal periodic vibration of soliton molecule.

physics.optics↗

arXiv2022

Synchronization of the internal dynamics of optical soliton molecules

Optical soliton molecules in ultrafast lasers present striking analogies with their matter molecule counterparts, such as internal vibrations. However, the vibrations of soliton molecules are nonlinear, with frequencies that are sensitive to the system parameters, thus presenting an opportunity of control. Here, we experimentally demonstrate the synchronization of the internal vibrations of self-excited vibrating soliton molecules through a modulated optical injection. We show efficient sub-harmonic, fundamental and super-harmonic synchronization, forming a pattern of Arnold tongues with respect to the injection strength. Our observations are supported by numerical simulations.

nlin.PS↗

arXiv2021

Power spectral density analysis of relative comb-line phase jitter in a twin-soliton molecule

Investigation on the relative phase evolution between two bounded optical solitons is essential for its potential applications in development of larger telecommunication capacity of optical fiber transmission lines, resolution improvement in advancing ultrafast characterization approaches and development of all-optical information storage. Here we characterized relative comb-line phase jitter power spectral density (PSD) of a soliton molecule pair generated from a passively mode-locked Er:fiber laser. Through tracking the intensity difference between two selected wavelengths in one certain spectral interference fringe, the relative comb-line phase noise PSD is measured by balanced detection. The estimated measurement resolution is at 10^(-14) rad2/Hz level and the estimated integrated phase noise from 10 MHz to 100 Hz is 2.04 mrad. The estimated relative linewidth is far below 1 mHz. Comparison between phase noise PSD and intensity noise PSD indicates that AM-PM conversion plays an important role in relative phase jitter dynamics between the two solitons. Our spectral interference fringe tracking technique is attractive for its simplicity and shows potential in ultra-high resolution in phase noise measurement, providing an ultra-sensitive alternative approach for relative phase noise stabilization of optical soliton molecules, between two independent mode-locked lasers and optical length stabilization of interferometers.

physics.optics↗

arXiv2020

Narrow-linewidth optical frequency comb reference to a fiber delay line

In this letter, we derive a fully-stabilized narrow-linewidth optical frequency comb (OFC) reference to a kilometer-long fiber delay line for the first time, to the best of our knowledge. The 1537-nm comb modes and 1566-nm comb modes in the OFC are phase-locked to the fiber delay line with 40-kHz locking bandwidth. From out-of-loop measurement, the 1542-nm comb mode has residual phase noise of 925 mrad (integrated from 10 MHz to 1 kHz), fractional frequency stability of 9.13*10(-13) at 12.8 ms average time and 580 Hz linewidth. The linewidth has been compressed by a factor of ~ 170 compared to the free-running condition. Short-term stability of presented OFC exceeds most commercial microwave oscillators. The entire phase-locking system is compact and highly-integrated benefiting from absence of optical amplifiers, f-2f interferometers and optical/radio references. The presented OFC shows significant potential of being reliable laser source in low-noise-OFC-based precise metrology, microwave generation and dual-comb spectroscopic applications outside the laboratory.

physics.optics↗

arXiv2015

Chromatic annuli formation and sample oxidation on copper thin films by femtosecond laser

We report an experimental investigation on the irradiation of copper thin films with high repetition rate femtosecond laser pulses (1040 nm, 50 MHz), in ambient air and liquid water. We observe a novel, striking phenomenon of chromatic copper oxides (cupric oxide and cuprous oxide) annuli generation. The characteristic features of the chromatic copper oxide annuli are studied by exploiting micro-Raman Spectroscopy, Optical and Scanning Electron Microscopies. In the case of irradiation in water, the seldom investigated effects of the immersion time, after irradiation with a fixed number of pulses, is analyzed, and an intriguing dependence of the color of the chromatic annuli on the immersion time is observed. This remarkable behavior is explained by proposing an interpretation scenario addressing the various processes involved in the process. Our experimental findings show that cuprous oxide nanoparticles (size of ~20 nm) and cuprous oxide nanocubes (nanocube edges of ~30, ~60 nm) with extremely fine sizes can be effectively generated by exploiting high repetition rate laser-assisted oxidation.

cond-mat.mtrl-sci↗

arXiv2015

Photostimulation activates restorable fragmentation of single mitochondrion by initiating oxide flashes

Mitochondrial research is important to ageing, apoptosis, and mitochondrial diseases. In previous works, mitochondria are usually stimulated indirectly by proapoptotic drugs to study mitochondrial development, which is in lack of controllability, or spatial and temporal resolution. These chemicals or even gene techniques regulating mitochondrial dynamics may also activate other inter- or intra-cellular processes simultaneously. Here we demonstrate a photostimulation method on single-mitochondrion level by tightly-focused femtosecond laser that can precisely activate restorable fragmentation of mitochondria which soon recover their original tubular structure after tens of seconds. In this process, series of mitochondrial reactive oxygen species (mROS) flashes are observed and found very critical to mitochondrial fragmentation. Meanwhile, transient openings of mitochondrial permeability transition pores (mPTP), suggested by oscillations of mitochondrial membrane potential, contribute to the scavenging of redundant mROS and recovery of fragmented mitochondria. Those results demonstrate photostimulation as an active, precise and controllable method for the study of mitochondrial oxidative and morphological dynamics or related fields.

q-bio.SC↗