Title

Tailoring Optoacoustic Brillouin Interaction of Cylindrical Vector Modes in Annular-Core Photonic Crystal Fiber

Abstract

Brillouin scattering in optical fibers has been widely studied over the last few decades and has given rise to numerous significant applications in optical sensing, laser technology, and optical communications. However, most Brillouin studies to date have focused on the fundamental modes; explorations of Brillouin scattering involving cylindrical vector modes, which possess diverse spatial information and polarization states, and have found applications in optical trapping, particle acceleration, and laser machining, still remain limited. Here, we report Brillouin scattering (including spontaneous and stimulated cases) of cylindrical vector modes in annular-core photonic crystal fiber and show robust nonreciprocal interaction between them via Brillouin-enhanced four-wave mixing, where two distinct Brillouin interactions involving different optical modes are coherently coupled through a common acoustic wave. Extending this principle to a resonant Brillouin laser cavity, we further demonstrate coherent oscillations of both optical and acoustic modes, leading to the stable emission of cylindrically vector beams with line widths of several kHz. These results pave the way for vector-mode Brillouin photonics, opening up opportunities for narrow-line-width structured light sources, reconfigurable nonreciprocal devices, and precision metrology.

DOI:10.1021/acsphotonics.5c02292 [Paper Link]

Corresponding authors

-Long Zhang, Email: lzhang@siom.ac.cn

-Xinglin Zeng, Email: zengxinglin@siom.ac.cn

Title

Modified Parameter-Scaling Rule of Nonlinear Pulse Propagation in Gas-Filled Capillary Fiber With Waveguide Loss Publisher: IEEE Cite This PDF

Abstract

Gas-filled capillary fiber has been widely regarded as an ideal platform for generating high energy, ultrashort laser pulses with broadband wavelength tunability, highly demanded in a few scientific areas. While a variety of soliton dynamics, such as high-order soliton self-compression (HSC), dispersive-wave emission (DWE) and ionization-induced spectral blue-shift (IBS), have been intensively studied in such a capillary fiber system, the parameter-scaling rule of this system is, however, different from that of the hollow-core photonic crystal fiber system, mainly due to the non-ignorable loss of the capillary waveguide. Here, we demonstrate a modified parameter-scaling rule which includes the capillary loss term, being useful to system design and optimization. We illustrate both theoretically and experimentally that this modified scaling rule is valid for all of the HSC, DWE and IBS processes, highlighting the similarities of these nonlinear propagation processes over a large range of capillary sizes.

DOI:10.1109/JLT.2026.3653762 [Paper Link]

Corresponding authors

-Zhiyuan Huang, Email: huangzhiyuan@siom.ac.cn

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Reducing Averaging Time in Dual-comb Spectroscopy via Phase-patterned Higher-repetition-rate Pulses

Abstract

Dual-comb spectroscopy (DCS) is a powerful Fourier-transform spectroscopic technique that provides high-speed, high-resolution, and broadband measurements without moving parts. However, the high peak power of mode-locked pulses can limit the photodetector’s dynamic range, resulting in a low signal-to-noise ratio (SNR) per acquisition. While coherent averaging can improve SNR, it sacrifices temporal resolution and demands stringent system stability. Here, we introduce a new approach to enhance SNR by using phase-patterned higher-repetition-rate combs. We reinterpret the self-imaging process of comb spectrum from a new perspective on mode interference among sub-pulse trains. As a proof-of-concept, we densified two 250-MHz frequency combs to 12.5-MHz mode spacings via phase modulation and performed DCS on an H¹³C¹⁴N gas cell, and compared the results with an emulated conventional 12.5-MHz DCS, demonstrating a 17-fold increase in mode amplitude. This concept is expected to be combined with ultra-high repetition rate combs, such as microcombs, and thereby deployed in practical applications that typically require spectral sampling spacings from hundreds of MHz to GHz range.

DOI:10.1364/OE.580101 [Paper Link]

Corresponding authors

Title

Spectral-Temporal Stretching and Bandwidth Scaling in Soliton Fiber Lasers Induced by Large Lumped Attenuation

Abstract

Soliton fiber laser is widely regarded as the paradigm for ultrafast fiber lasers due to its simple and flexible configuration. Meanwhile, to overcome its limitation in pulse energy and bandwidth, dispersion-management and spectral filtering effects are routinely used to mitigate nonlinearity-induced instabilities through temporal and spectral stretching in the cavity. In this work, we demonstrate that, by simply introducing a large lumped attenuation in a soliton fiber laser, significant temporal and spectral stretching can be achieved despite the dominant anomalous dispersion of the fiber cavity, allowing for a stretched-pulse-like operation without using dispersion-compensation fibers and bandpass filters. In experiment, we achieved prominent pulse energy and bandwidth scaling by applying a lumped 13-dB attenuation before the gain section, which leads to 8-nm pulse bandwidth. Numerical simulations were performed to reveal the dramatic oscillation of the pulse chirp in the cavity in the all-anomalous fiber sections. This work revealed the critical role of lump attenuation in mode-locked cavity in manipulating the intra-cavity dynamics of soliton laser, and may serve as a simple and useful degree of freedom for optimization of mode-locked fiber lasers.

DOI:10.1109/JPHOT.2025.3643502 [Paper Link]

Corresponding authors

-Xintong Zhang, Email: xintong.zhang@r-cals.com

-Wenbin He, Email: wenbin.he@siom.ac.cn

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Ultrasensitive, High Dynamic Range Real-time Tetracycline Detection via Perovskite-functionalized Hollow-core Anti-resonant Fiber Sensors

Abstract

Tetracycline (TC), a widely used antibiotic, is known for posing persistent pollutant in the natural environment. The monitoring of its concentration is challenging due to its low natural degradation rate. Addressing this issue, we demonstrate a novel hollow-core anti-resonant fiber (HC-ARF)-based chemical sensor, integrated with perovskite nanomaterials for ultrasensitive TC detection. The sensor employs a CsPbBr₃-TMOS nanocomposite, synthesized via hydrolysis of tetramethyl orthosilicate (TMOS), which confers exceptional hydrolytic stability while preserving the perovskite’s optoelectronic performance. This composite exhibit selective fluorescence quenching via photoinduced electron transfer (PET) upon TC binding, enabling target-specific detection. Based on the above mechanism, a TC-sensitive HC-ARF chemical sensor is developed by immobilizing the fiber inner surface with CsPbBr₃-TMOS nanoparticles through electrostatic self-assembly, creating a spatially optimized sensing interface. Simultaneously, the hollow channels of the HC-ARF serve as microfluidic channels for aquatic analyte, enhancing light-liquid interaction via low-loss guidance of fiber transverse modes. This design utilizes the HC-ARF’s high surface-to-volume ratio and infinite length of beam focus, overcoming diffusion-limited kinetics inherent to bulk solution-based sensing. This TC sensor performs a dynamic range of 0.1–500 μM and a detection limit of 11 nM, representing a ∼ten-time improvement in sensitivity over conventional cuvette-based fluorescence assays. By integrating perovskite optoelectronics with HC-ARF’s optical performance, this platform enables real-time, in situ chemical monitoring with minimal sample volumes of sub micro-liter level, ideal for deployable environmental sensors.

DOI:10.1016/j.snb.2025.139239 [Paper Link]

Corresponding authors

-Xin Jiang, Email: xin.iiang@r-cals.com

Title

Endlessly Single-mode, Broadband Polarization-maintaining Solid-core Photonic Crystal Fiber

Abstract

We present a polarization-maintaining photonic crystal ffber (PM-PCF), featuringa hybrid lattice structure that simultaneously achieves broadband single-mode guidance andenhanced birefringence through coordinated geometric and cross-optical-mode modulation. Theffber structure incorporates a hybrid triangular air-hole arrangement and a slightly elliptical core, effectively enhancing birefringence while enabling endlessly single-mode operation.Experimental results reveal a group birefringence of 5.6 × 10⁻⁵at 1550 nm, the suppression ofpolarization mode coupling with an h-parameter below 1.2 × 10⁻⁴ m⁻¹, and broadband singlemode operation across 600 to 1600 nm. This ffber combines high PM capability with broadbandsingle-mode performance, offering potential applications in optical communication, high-powerlaser systems, and ffber optic sensing.

DOI:10.1364/OE.581512 [Paper Link]

Corresponding authors

-Zhuozhao Luo, Email: zhuozhao.luo@r-cals.com

-Meng Pang, Email: pangmeng@siom.ac.cn

-Xin Jiang, Email: xin.iiang@r-cals.com

Title

Stochastic Collapse and Recovery of Optical Solitons in Harmonic Mode-locked Lasers Under Pump Perturbations

Abstract

Harmonically mode-locked soliton fiber laser can host an ensemble of identical solitons in parallel, providing a unique many-body system for exploring the intrinsic stochasticity of soliton dynamics in nonlinear optical systems. We report in this work the experimental observation of parallel soliton dynamics under homogeneous perturbation in a harmonically mode-locked fiber laser. Given an abrupt and transient decrease in the pump power, the parallel solitons exhibit evolution trajectories of probabilistic nature, featuring prominent re-distribution of soliton energies followed by random collapse and recovery after the perturbation. We investigate statistical dependences of the soliton collapse upon the perturbation parameters, while revealing threshold behaviors of the recovery dynamics. This work provides unique insight into the stochasticity of the nonlinear soliton evolution in mode-locked fiber lasers and may help to improve laser stability.

DOI:10.1364/OL.571324 [Paper Link]

Corresponding authors

-Wenbin He, Email: wenbin.he@siom.ac.cn

Title

Vertically Stacked Boron Nitride/Graphene Heterostructure for Tunable Antiresonant Hollow-Core Fiber

Abstract

Incorporating atomically thin two-dimensional (2D) materials with optical fibers expands their potential for optoelectronic applications. Recent advancements in chemical vapor deposition have enabled the batch production of these hybrid fibers, paving the way for practical implementation. However, their functionality remains constrained by the integration of a single 2D material, restricting their versatile performance. Here, we introduce a boron nitride/graphene (BN/Gr) heterostructure in the antiresonant hollow-core fiber (ARF) to modulate its optical resonance and thus enhance graphene nonlinearity by controlling the BN thickness. Hydroxyl-rich methanol is employed to improve the flatness and crystallinity of graphene, promoting the vertical epitaxy of BN with a controllable thickness ranging from 5 to 50 nm. The engineered optical resonance notably tunes the light–graphene interaction within the BN/Gr-ARF, increasing the depth of nonlinear optical modulation from 4% to 10% and enhancing all-optical modulation performance by 75%. Our methodology opens possibilities for tunable optical waveguides via the direct growth of functional 2D material-based heterostructures, offering a robust platform for the development of highly integrated photonic devices.

DOI:10.1021/jacs.5c09658 [Paper Link]

Corresponding authors

Title

2D Molybdenum Disulfide Embedded Photonic Crystal Fiber for all-Fiber Phase Retarder

Abstract

The integration of 2D materials with optical fibers enables multifunctional fiber devices, such as polarizers, modulators, and sensors. Recent advances in direct vapor deposition growth further enhance light-2D material interactions to centimeter-scale lengths, overcoming the micrometer-scale limitations of transferred 2D materials. However, conventional methods for growing 2D materials in fibers typically produce isotropic material architectures due to uniform precursor deposition, limiting applications that require birefringence, such as a phase retarder. Here, a selective vapor deposition method is proposed to realize the non-circular symmetric growth of 2D molybdenum disulfide (MoS₂) into photonic crystal fibers (PCFs), achieving anisotropy-engineered phase retardation. The high refractive index of MoS₂ efficiently breaks the degeneracy of polarization modes in PCF and enables phase retardation with a manageable beat length of ≈7.7 cm. The MoS₂-PCF phase retarder reliably works in varying conditions, including outdoor exposure, large deformation, and high temperature/humidity. Its phase retardation exhibits an extremely small fluctuation of ≈3.3° between 25 and 200 °C, which is two orders of magnitude lower than that of commercial polarization-maintaining fibers (≈2.0°/°C). The work provides a new solution for the fiber device preparation and pave the way for robust polarization manipulation in all-fiber systems.

DOI:10.1002/adma.202504464 [Paper Link]

Corresponding authors

Title

High-quality Delivery of High-power Picosecond Laser in Single-ring Anti-resonant Hollow-core Fiber for Micromachining

Abstract

We present the flexible delivery of picosecond laser pulses with up to 20 W average power over a 3-m-long sample of anti-resonant hollow-core fiber (AR-HCF) for laser micromachining applications. Our experiments highlight the importance of optical  mode purity of the AR-HCF for the manufacturing precision. We demonstrate that compared with an AR-HCF sample with a capillary to core (d/D) ratio of ~0.5, the AR-HCF with a d/D ratio of ~0.68 exhibits better capability of high-order-mode suppression, giving rise to improved micromachining quality. Moreover, the AR-HCF delivery system exhibits better pointing stability and setup flexibility than the free-space beam delivery system. These results pave the way to practical applications of AR-HCF in developing advanced equipment for ultrafast laser micromachining.

DOI:10.1017/hpl.2025.10063 [Paper Link]

Corresponding authors

-Zhiyuan Huang, Email: huangzhiyuan@siom.ac.cn

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Tunable VUV-to-VIS Ultrafast Pulses Generation in Hollow Capillary Fibers with 15.7% Dispersive-wave Efficiency at 320 nm

Abstract

We report a compact hollow-capillary-fiber (HCF) system that generates tunable dispersive-wave (DW) pulses spanning the vacuum ultraviolet (VUV) to visible (VIS) spectral regions. Through optimization of the HCF and gas parameters, we demonstrate continuously tunable DW generation with a wider tuning range (147-520 nm) than previously reported in similar compact systems (200-380 nm). Using a 140-μm-core, 1-m-long helium-filled HCF, we enhance deep-UV pulse generation efficiency via spectral blue-shifting of the DW at a relatively high soliton order, achieving a record 15.7% conversion efficiency at 320 nm. This work provides key insights for developing compact, tunable, and microjoule-level ultrafast VUV-to-VIS laser systems based on DW emission.

DOI:10.1364/OE.568546 [Paper Link]

Corresponding authors

-Zhiyuan Huang, Email: huangzhiyuan@siom.ac.cn

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Three-stage Dynamics of Nonlinear Pulse Amplification in an Ultrafast Mid-infrared Fiber Amplifier with Anomalous Dispersion

Abstract

Nonlinear pulse amplification in optical fiber, with the capability of breaking the gain-bandwidth limitation, is a key technique for high-energy, ultrafast pulse generation. In the longer wavelength region (including 1.55µm, 2µm and 2.8µm) where the gain fiber has normally strong anomalous dispersion, the nonlinear amplification process over fiber exhibits more complicated dynamics than that of its 1-µm counterpart, and the underlying mechanism of the nonlinear pulse propagation process in high-gain anomalous fiber is still elusive so far. Here, we demonstrate an in-depth study on the nonlinear amplification process in high-gain ultrafast mid-infrared fiber, providing a clear physical understanding on the debate of adiabatic soliton compression. We unveil that under the high-gain condition, the ultrafast pulse launched into the anomalous gain fiber experiences successively three distinct stages, named as the balance between linear and nonlinear chirp, high-order-soliton-like pulse compression and soliton fission due to high-order effects. While a relatively clean ultrafast pulse can be obtained immediately after the high-order-soliton-like compression stage, excessive gain fiber length could hardly enhance further the pulse peak power due to soliton fission. Our findings can provide several critical guidelines for designing high-power ultrafast fiber amplifiers at near- and mid-infrared wavelengths.

DOI:10.1364/OE.564519 [Paper Link]

Corresponding authors

-Jiapeng Huang, Email: jiapenghuang@siom.ac.cn

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Flexible Delivery of Broadband, 100 fs Mid-infrared Pulses in the Water-absorption Band Using Hollow-core Photonic Crystal Fiber

Abstract

High-quality free-space and over-fiber transmission of mid-infrared light is limited by factors such as material-related absorption,diffraction,lightleakage,andnonlinearity.Conventionalvacuumapparatuscanbeutilizedforhigh-quality laser-beam delivery to address these issues; however, the deployment of such apparatus would increase system com plexity, which is detrimental to their practical applications. Here, we report the successful use of evacuated hollow-core photonic crystal fiber (PCF) to flexibly transmit ultrafast mid-infrared pulses over several meters, while preserving exceptional spatial, spectral, and temporal fidelities. The PCF was engineered to feature a low-loss transmission band within the water absorption range, and an evacuated 5 m length was used to transmit Watt-level, 100 fs pulses centered at ~2.8 m. A comparison between free-space transmission and air-filled PCF highlights the superior performance of the evacuated hollow-core PCF, indicating its strong suitability for the flexible delivery of sub-ps laser pulses in the mid-infrared.

DOI:10.1364/OPTICA.558579 [Paper Link]

Corresponding authors

-Jiapeng Huang, Email: jiapenghuang@siom.ac.cn

-Xin Jiang, Email: xin.jiang@r-cals.com

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Experimental Studies on the Structural Dependence of Stimulated Raman-like Scattering in Solid-core Photonic Crystal Fibers

Abstract

The tight confinement of both optical and acoustic fields in their µm-sized fiber cores of photonic crystal fibers (PCFs) can lead to enhanced Brillouin light scattering in the forward direction, which is well-known as the stimulated Raman-like scattering (SRLS). In general, the gain spectra of SRLS in PCFs are dominated by the PCF core sizes. Meanwhile, their exact dependences upon the surrounding hollow channels have not been systematically studied in experiments. In this work, we investigated a series of PCF samples with systematically varied core diameters and air-filling ratios and unveiled several key impacts of the PCF air channels upon their gain spectrum in terms of the gain strength, the frequency shift and multi-peak structure, together with physical interpretations of the underlying mechanism. Our work provides some practical guidance for PCF design in potential applications that employ SRLS in mode-locked lasers and opto-acoustic isolators.

DOI:10.1364/OE.555671 [Paper Link]

Corresponding authors

-Wenbin He, Email: wenbin.he@r-cals.com

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Tunable Ultraviolet Dispersive-wave Emission Driven Directly by 40-fs Ti:sapphire Laser Pulses in a Hollow Capillary Fiber

Abstract

We demonstrate that by using a 1-m-long gas-filled hollow capillary fiber (HCF) with a core diameter of 100 μm, tunable ultraviolet (UV) dispersive-wave (DW) pulses can be generated in a compact, single-stage setup driven directly by 40-fs Ti:sapphire laser pulses. By adjusting the gas type and pressure inside the HCF, the central wavelength of the UV DW can be continuously tuned from 185 nm to ∼450 nm. In the experiment, we found that for ∼320–450 nm DW generation, Raman-active gas filled in the HCF can efficiently suppress the pulse fission effect of the high-order soliton due to the Raman-induced pulse energy dissipation, leading to the high-quality DW generation at these wavelengths with smooth, single-peak spectra. These results provide some useful insights for designing compact, wavelength-tunable ultrafast UV light sources with microjoule-level pulse energies.

DOI:10.1364/OL.553345 [Paper Link]

Corresponding authors

-Zhiyuan Huang, Email: huangzhiyuan@siom.ac.cn

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Wavelength-tunable, Mid-infrared Ultrafast Pulse Generation Through Raman Self-frequency Shift in an All-solid Fluorotellurite Fiber

Abstract

We report a mid-infrared (mid-IR) fiber laser system that can deliver ultrafast soliton-like pulses with a wavelength tunable from 2.8 to 4.0 μm. The pump light source of the system is a mid-IR fiber laser mode-locked at 2.8 μm, which has an average output power of ∼500 mW, a repetition rate of ∼30 MHz, a pulse energy of ∼15 nJ, and a pulse duration of ∼150 fs. The pump light was then launched into a short (∼70 cm) sample of fluorotellurite (TeO2-BaF2-Y2O3) glass fiber as the high-nonlinearity waveguide with simultaneously good features of large Raman gain, tailored dispersion, and high-power capability. High-efficiency Raman soliton self-frequency-shift phenomenon can be obtained in this short fiber sample, leading to the generation of broadband tunable (3–4 μm), mid-IR pulses with hundreds-of-fs pulse duration and tens-of-mW average power, corresponding to a pulse energy level of ∼1 nJ. The frequency-conversion efficiency inside the nonlinear fiber was measured to be as high as ∼16%. The present system, combining the advanced techniques of fluorotellurite fiber fabrication and mid-IR ultrafast fiber laser, highlights its application potentials for generating low-noise, high-beam-quality, mid-IR ultrafast pulses with a compact fiber configuration.

DOI:10.1364/OL.559304 [Paper Link]

Corresponding authors

-Jiapeng Huang, Email: jiapenghuang@siom.ac.cn

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Invited Commentary: Hollow Core Glass Fibre— the Perfect Pipe for Light

Abstract

DOI:10.1186/s43593-025-00086-w [Paper Link]

Corresponding authors

-Philip Russell, Email: philip.russell@r-cals.com

Title

Coherent Combination of Mid-IR Laser Beams Using a Sagnac-type Interferometer

Abstract

We report a high-efficiency coherent beam combination (CBC) system operating in the mid-infrared (2.8 µm) spectral region, implemented using two fluoride fiber amplifiers with a configuration of Sagnac-type interferometer. The system exhibits good performance at both continuous-wave (CW) and picosecond-pulse operation conditions. For the CW CBC, the system exhibits a high combination efficiency of >90%, delivering a maximum output power of 2.8 W with a beam quality factor (M2 ) of <1.2. When using a pulsed laser as the seed light, two beams of 1-ps pulses can be amplified and simultaneously temporally-compressed to ∼170 fs in the two fiber amplifiers. Then high-efficiency (∼84%) coherent combination of amplified ultrafast laser beams can be achieved in this CBC system, giving rise to a recombined output power of ∼1 W. These results highlight the application potential of this Sagnac-type CBC set-up for power scaling of both CW and ultrafast fiber lasers at mid-IR wavelengths.

DOI:10.1364/OE.558136 [Paper Link]

Corresponding authors

-Jiapeng Huang, Email: jiapenghuang@siom.ac.cn

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Observation of Dynamics of Harmonic Order Self-adaptation in Optoacoustically Mode-locked Fiber Laser

Abstract

High-harmonic mode-locking based on strong optoacoustic interactions in solid-core photonic crystal fiber (PCF) has been an established mechanism to achieve a stable GHz repetition rate in a conventional soliton fiber laser, in which a uniform pulse sequence is self-locked to the acoustic core-resonance of the PCF with a specific harmonic order. However, due to the finite bandwidth of the acoustic core-resonance, there may be multiple choices of harmonic order within the resonance bandwidth that could lead to uncertainties in the resultant harmonic order. In this work, we report observations of dynamic self-adaptation of the pulses in the laser cavity towards a stable harmonic order when the cavity is initially set at a neighboring less stable harmonic order. We observed that self-adaptation can occur spontaneously towards either higher or lower harmonic order depending on the initial condition. We observed rich dynamics during the self-adaptation process namely transient pulse sliding, random pulse collisions, and pulse drop-outs. This work provides experimental insight into the robustness of the self-locked repetition rate in optoacoustic mode-locking, and we believe will be useful in understanding and controlling harmonically mode-locked lasers.

DOI:10.1364/OE.547755 [Paper Link]

Corresponding authors

-Wenbin He, Email: wenbin.he@r-cals.com

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Retiming Dynamics of Harmonically Mode-locked Laser Solitons in a Self-driven Optomechanical Lattice

Abstract

Harmonic mode-locking, realized actively or passively, is an effective technique for increasing the repetition rate of ultrafast lasers. It is critically important to understand how a harmonically mode-locked pulse train responds to external perturbations and noise, so as to make sure that it is stable and resistant to noise. Here, in a series of carefully designed experiments, we elucidate the retiming dynamics of laser pulses generated in a soliton fiber laser harmonically mode-locked at GHz frequencies to the acoustic resonance in a photonic crystal fiber (PCF) core. We characterize the self-driven optomechanical lattice, which is distributed along the PCF and provides the structure that supports harmonic mode-locking, using a homodyne setup. We reveal that, after an abrupt perturbation, each soliton in the lattice undergoes damped oscillatory retiming within its trapping potential, while the retiming is strongly coupled to soliton dissipation. In addition, we show, through statistical analysis of the intra-cavity pulse spacing, how the trapping potentials are effective for suppressing timing jitter. The measurements and the theory developed in this work lay the groundwork for studies of the general stability and noise performance of harmonically mode-locked lasers as well as providing valuable insight into generic multi-pulse phenomena in mode-locked lasers.

DOI:10.1038/s41377-024-01736-3 [Paper Link]

Corresponding authors

-Wenbin He, Email: wenbin.he@r-cals.com

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Understanding Low-threshold Mode-locking at Multi-GHz Repetition Rate (News & Views)

Abstract

Continuous-wave mode-locking at multi-GHz repetition rates is achieved in an ultrashort laser cavity at critical pulse energies 100 times lower than predicted by conventional theory. The authors reveal that dynamic gain depletion and recovery between consecutive round-trips is the key factor behind a low-pulse-energy transition from Q-switched mode-locking (QSML) to continuous-wave mode-locking (CWML). As well as providing new insight into gain dynamics, the results suggest a practical route to low-threshold lasing at very high-repetition rates.

DOI:10.1038/s41377-024-01682-0 [Paper Link]

Corresponding authors

-Wenbin He, Email: wenbin.he@r-cals.com

Title

Ultraviolet-enhanced Flat Supercontinuum Light Generated in Cascaded Photonic Crystal Fiber

Abstract

We demonstrate that by using a cascaded configuration of five solid-core photonic crystal fiber (PCF) samples with progressively decreasing core diameters, ultraviolet light with wavelengths as short as ∼300 nm can be generated in a supercontinuum (SC) set-up. With a nanosecond laser as the pump light, the modulation instability effect leads to the generation of multiple optical solitons in the first PCF sample which has a close-to-zero dispersion value at the pump wavelength (∼1064 nm). The following PCF samples with decreasing core diameters enhance the waveguide nonlinearity, and at the same time provide continuously-shorter phase-matching wavelengths for dispersive-wave emission, thereby pushing the short-wavelength edge of the SC spectrum into the deep ultraviolet spectral region. While the PCF splicing technique ensures the compactness of this SC set-up, the generated SC spectrum, spanning ∼350 nm to ∼2000 nm with a flat spectral profile, may be applied in fluorescence microscopy and biochemical imaging.

DOI:10.1109/JPHOT.2024.3488039 [Paper Link]

Corresponding authors

-Zhiyuan Huang, Email: huangzhiyuan@siom.ac.cn

-Meng Pang, Email: pangmeng@siom.ac.cn

-Xin Jiang, Email: xin.jiang@r-cals.com

Title

Three Decades Riding the Photonic Crystal Fiber Wave: an Interview with Prof. Philip Russell

Abstract

DOI:10.1117/1.AP.6.6.060501 [Paper Link]

Corresponding authors

-Long Zhang

Title

High Power Mid-infrared Side-pump Combiner with Good Thermal Stability Based on the Point-by-point Fusion Splicing Technique

Abstract

High-power mid-infrared fiber lasers, featuring superior beam quality and good power-scaling ability, have a few important applications in material processing, medical surgery, and molecule spectroscopy. The high-power pump light combiner, as one of the key elements for constructing a mid-infrared fiber laser, is crucial for the laser performance. While some advanced side-pump combiners based on fluoride fiber have been reported in recent literatures, the thermal stability of the fluoride fiber combiner, which is closely-related to its power-scaling capability, is a long-living challenge. In this work, we demonstrate a high-power mid-infrared side-pump combiner with improved thermal stability, realized using the point-by-point fusion-splicing technique between a silica fiber taper and a piece of Er-doped fluoride gain fiber. The developed combiner exhibits a high coupling efficiency of ∼90%, supporting highly-stable operation at an incident pump power of up to 60 W. Using this combiner, we constructed a continuous-wave mid-infrared fiber laser which can deliver stably 4 W output power at 2.8 µm without using active cooling system. At this lasing power, the maximum input pump power is limited to 20 W to prevent fiber end-facet degradation, which can be further improved with the use of endcaps. This remarkable thermal stability renders the combiner great application potentials in constructing compact, robust, high-power fiber lasers at mid-infrared wavelengths.

DOI:10.1364/OE.538468 [Paper Link]

Corresponding authors

-Jiapeng Huang, Email: jiapeng.huang@r-cals.com

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Octave-wide Broadening of Ultraviolet Dispersive Wave Driven by Soliton-splitting Dynamics

Abstract

Coherent dispersive wave emission, as an important phenomenon of soliton dynamics, manifests itself in multiple platforms of nonlinear optics from fibre waveguides to integrated photonics. Limited by its resonance nature, efficient generation of coherent dispersive wave with ultra-broad bandwidth has, however, proved difficult to realize. Here, we unveil a new regime of soliton dynamics in which the dispersive wave emission process strongly couples with the splitting dynamics of the driving pulse. High-order dispersion and self-steepening effects, accumulated over soliton self-compression, break the system symmetry, giving rise to high-efficiency generation of coherent dispersive wave in the ultraviolet region. Simultaneously, asymmetric soliton splitting results in the appearance of a temporally-delayed ultrashort pulse with high intensity, overlapping and copropagating with the dispersive wave pulse. Intense cross-phase modulations lead to octave-wide broadening of the dispersive wave spectrum, covering 200–400 nm wavelengths. The highly-coherent, octave-wide ultraviolet spectrum, generated from the simple capillary fibre set-up, is in great demand for time-resolved spectroscopy, ultrafast electron microscopy and frequency metrology applications, and the critical role of the secondary pulse in this process reveals some new opportunities for all-optical control of versatile soliton dynamics.

DOI:10.1038/s41467-024-52955-6 [Paper Link]

Corresponding authors

-Zhiyuan Huang, Email: huangzhiyuan@siom.ac.cn

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Critical-layered MoS₂ for the Enhancement of Supercontinuum Generation in Photonic Crystal Fibre

Abstract

Supercontinuum generation (SCG) from silica-based photonic crystal fibers (PCFs) is of highly technological significance from microscopy to metrology, but has been hindered by silica's relatively low intrinsic optical nonlinearity. The prevailing approaches of filling PCF with nonlinear gases or liquids can endow fibre with enhanced optical nonlinearity and boosted SCG efficiency, yet these hybrids are easily plagued by fusion complexity, environmental incompatibility or transmission mode instability. Here this work presents a strategy of embedding solid-state 2D MoS2 atomic layers into the air-holes of PCF to efficiently enhance SCG. This work demonstrates a 4.8 times enhancement of the nonlinear coefficient and a 70% reduction of the threshold power for SCG with one octave spanning in the MoS2-PCF hybrid. Furthermore, this work finds that the SCG enhancement is highly layer-dependent, which only manifests for a real 2D regime within the thickness of five atomic layers. Theoretical calculations reveal that the critical thickness arises from the trade-off among the layer-dependent enhancement of the nonlinear coefficient, leakage of fundamental mode and redshift of zero-dispersion wavelength. This work provides significant advances toward efficient SCG, and highlights the importance of matching an appropriate atomic layer number in the design of functional 2D material optical fibers.

DOI:10.1002/adma.202403696 [Paper Link]

Corresponding authors

Title

Spectral Bandwidth Tuning of Photoionization-induced Blue-shifted Solitons in Gas-filled Hollow-core Anti-resonant Fibers

Abstract

Frequency blue shift of optical solitons, due to light-plasma interactions is an important nonlinear process of laser frequency up-conversion in gas-filled hollow-core fibers, which can be applied for generating ultrafast pulses with tunable wavelengths covering infrared and visible regimes. While the mechanism of photoionization in this frequency up- conversion process has been well studied for a few years, the spectral width tunability of output ultrafast pulses generated in such a hollow-core fiber system has not been comprehensively investigated yet. Here, we demonstrate that the theory of adiabatic soliton propagation could be used to understand the spectral bandwidth evolution of photoionization-induced blue-shifted solitons in gas-filled hollow-core anti-resonant fibers. Experimentally, through varying the gas pressure in the hollow-core fiber and the input pulse energy, high-repetition-rate (10 kHz) tunable ultrafast pulses were obtained at the fiber output with a central wavelength tuning range from ∼900 nm to ∼650 nm and a bandwidth tuning range (at 700 nm) from ∼100 nm to ∼180 nm, corresponding to chirp-compensated pulse width tuning from 7.2 fs to 5.4 fs. These experimental results agree well with the theoretical predictions, and the femtosecond visible light source with high-flexible pulse parameters, demonstrated here, may have some potentials in ultrafast spectroscopy and nonlinear-optics applications.

DOI:10.1109/JSTQE.2024.3420428 [Paper Link]

Corresponding authors

-Zhiyuan Huang, Email: huangzhiyuan@siom.ac.cn

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Broadband Dispersive-wave Emission Coupled with Two-stage Soliton Self-compression in Gas-filled Anti-resonant Hollow-core Fibers

Abstract

The underlying mechanism of broadband dispersive-wave emission within a resonance band of gas-filled anti-resonant hollow-core fiber is studied. Both numerical and experimental results unveiled that the pump pulse with a soliton order of ≈3, launched into the hollow-core fiber, experienced two stages of pulse compression, resulting in a multi-peak structure of the emitted dispersive-wave spectrum. Over the first-stage pulse compression, a sharp increase of the pulse peak power triggers the first time of dispersive-wave emission, and simultaneously causes the soliton frequency blue-shift due to soliton-plasma interactions. As the central frequency of the blue-shifting soliton approaches to a resonance band of the hollow-core fiber, it experiences a fast-decreasing dispersion value in the fiber waveguide, resulting in the second stage of pulse compression. The second-stage pulse compression triggers the second time of dispersive-wave emission with a phase-matched frequency slightly lower than that at the first stage. Multi-peak spectra of the output dispersive-waves and their formation dynamics can be understood using a delicate and unique coupling mechanism among three nonlinear effects including multi-stage soliton compression, soliton-plasma interaction, and phase-matched dispersive-wave emission. The output broadband dispersive-wave, exhibiting good coherence and stability, can be potentially compressed to sub-30 fs duration using a precise chirp-compensation technique.

DOI:10.1002/lpor.202400531 [Paper Link]

Corresponding authors

-Zhiyuan Huang, Email: huangzhiyuan@siom.ac.cn

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

GHz-rate 57-fs Optoacoustic Mode-locking Fiber Laser Based on Cascaded All-fiber Pulse Compression

Abstract

We demonstrate a compact ultrafast fiber laser system that can deliver 1.87 GHz pulse train at 1550 nm with a pulse energy of 52 pJ and an ultrashort pulse duration of 57 fs. While an acousto-optic mode-locking fiber laser was used as the seed light source at GHz rate, a stage of Er-doped fiber amplifier boosted the laser power to ∼320 mW, giving a pulse energy of ∼170 pJ. Then, a pulse compression setup was constructed, providing a high compression ratio of ∼10 with a total efficiency of ∼32%. In the cascaded compression configuration, multiple fiber samples with alternately normal and anomalous dispersion were fused together, providing efficient nonlinear spectral broadening while suppressing excessive pulse broadening over propagation. This GHz-rate ultrafast fiber laser, with compact configuration, broad optical spectrum, and high time-resolving ability could be used as the seed light source for constructing high-rate, high-power ultrafast laser systems and may find a few applications in optical measurements and microwave photonics.

DOI:10.1364/OL.520119 [Paper Link]

Corresponding authors

-Wenbin He, Email: wenbin.he@r-cals.com

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Quadratic Phase Mismatch in Multisoliton Interferograms Based on Time-stretched Dispersive Fourier Transformation

Abstract

The time-stretched dispersive Fourier transform method (TS-DFT) has been widely used to analyze multisoliton structures in ultrafast lasers, featuring shot-by-shot access to their spectral interferograms. Most exemplary structures consist of two interacting solitons whose spacing and relative phase can be simply retrieved from their interferograms mapped in time domain by TS-DFT. However, such analysis has not been elaborated for structures with more solitons that could result in a complicated TS-DFT signal. Here we report our theoretical inference of a deterministic discrepancy when retrieving structures consisting of more than two solitons with their TS-DFT signal. We unveil the underlying source of these discrepancies as a result of the quadratic phase mismatch induced by TS-DFT and correspondingly propose an improved retrieval method. Our work may provide a theoretical guideline for conducting unambiguous analysis of complex multipulse structures using TS-DFT, particularly when the dispersive stretching ratio is limited.

DOI:10.1103/PhysRevA.109.053524 [Paper Link]

Corresponding authors

-Wenbin He, Email: wenbin.he@r-cals.com

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Intrinsic Discrepancy of Multi-Soliton Interferogram in Dispersive Fourier Transform Measurements Due to Impulsive Response of Fast Electronics

Abstract

Time-stretched dispersive Fourier transform (TS-DFT) technique has been widely used for studying transient soliton dynamics due to its unique capability of direct time-frequency mapping of ultrafast pulses in the real time. Particularly, multi-soliton structures that are ubiquitous in ultrafast lasers have been routinely analyzed using TS-DFT technique, giving concurrently spacing and relative-phase information during soliton interactions. While the TS-DFT signal recorded by the fast electronics would inevitably deviate from the genuine spectral interferogram, the consequent discrepancies have not, however, been systematically interrogated yet. In this work, we performed detailed comparisons between the temporal TS-DFT signal of multi-soliton structures (with tunable spacings and phases) and their genuine spectral interferograms measured using optical spectrum analyzer. We revealed that due the impulsive response of the detection system, the retrieved relative-phases from the TS-DFT signal could have non-trivial discrepancies from their actual values, even though the bandwidth of the detection electronics is a few times broader than that of the TS-DFT signal. Our findings can help to provide clearer insights in multi-soliton dynamics using TS-DFT technique.

DOI:10.1109/JLT.2024.3399198 [Paper Link]

Corresponding authors

-Wenbin He, Email: wenbin.he@r-cals.com

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Kilohertz-linewidth Brillouin Photonic Crystal Fiber Laser with Non-resonance Pumping Configuration

Abstract

Brillouin fiber laser with the non-resonance pumping configuration, has compact set-up, good wavelength tunability and high-power single-frequency-emission capability, being regarded as an important technique for highly-coherent light generation. Such Brillouin fiber lasers, using single-mode fiber (SMF) as the Brillouin gain medium, generally have high lasing thresholds and mode-hopping instabilities, resulting from the relatively-low Brillouin gain coefficient of the conventional SMF. Here, we report a compact, non-resonance-pumping Brillouin photonic crystal fiber laser that can generate kHz-level-linewidth single-frequency lasing with tens-of-mW lasing threshold. Mode-hopping instability of this laser is largely suppressed thanks to the short (∼20 m) cavity length, which gives rise to a free-spectral-range (FSR) value of ∼10 MHz properly matching the tens-of-MHz Brillouin gain bandwidth. Experimental results of both self-heterodyne and frequency-noise measurements indicate a laser linewidth of ∼1.4 kHz, corresponding to high linewidth-narrowing ratio of ∼18. No lasing line of high-order Stokes was observed in experiments as the laser pump power was gradually increased to ∼200 mW, giving a nearly-linear lasing slope.

DOI:10.1109/JPHOT.2024.3399030 [Paper Link]

Corresponding authors

-Wenbin He, Email: wenbin.he@r-cals.com

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Non-markovian Doppler Velocimetry of Optically Propelled Microparticles in Hollow-core Photonic Crystal Fiber

Abstract

Doppler velocimetry has been widely used in many aspects of research and in applications. The conventional algorithm for tracking Doppler frequencies can induce large errors in the extracted particle velocity when the signal-to-noise ratio of the Doppler signal is low. Ambiguities in velocity identification are also present when multiple measured objects are moving at similar speeds. Here, we report non-Markovian Doppler velocimetry based on a time–frequency ridge extraction algorithm in which features of the historic trajectories are introduced to track the object’s instantaneous velocity. We demonstrate the technique on optically trapped dielectric microparticles in a hollow-core photonic crystal fiber. The technique can improve the accuracy of particle velocity tracking by more than 2 orders of magnitude in the low signal-to-noise regime and is capable of resolving the issue of multiple-particle velocity extraction. The proposed technique can improve the accuracy, sensitivity, and dynamic range of Doppler velocimetry related to vast numbers of applications.

DOI:10.1021/acsphotonics.3c01692 [Paper Link]

Corresponding authors

Title

Sub-ppm NO₂ Gas Sensing in CdTe Quantum Dots Functionalized Hollow-core Anti-resonant Fiber

Abstract

Recently emerged hollow-core fiber provides an excellent platform for various studies due to its remarkable features, such as broadband transmissions, enhanced light-matter overlapping, ultra-low nonlinearity, low latency and dispersion. At the same time, it is generally known that nitrogen dioxide (NO₂) is deemed a common air pollutant. Detecting its concentration is essential, covering environmental monitoring, industrial manufacturing, and human safety issues. Accurate detection of NO₂ in gaseous state, however, has been a long-existing challenge due to the requirements for high sensitivity, compatible equipment, short sampling duration, etc. Here, a novel approach is reported for measuring NO₂ gas by functionalizing a hollow-core anti-resonant fiber (HC-ARF) with CdTe-deposited quantum dots (QDs). The mechanism is based on fluorescence quenching of glutathione-capped CdTe QDs, triggered by NO2 gas. The hollow-core fiber works as a micro-reactor that enhances gas/light interactions. Consequently, the sensitivity can be effectively increased for detecting sub-ppm concentration (∼0.1 ppm) NO2 gas, with high efficiency, small sample volume, and short sampling durations of only a few minutes, much faster than that in many non-fiber-based systems. Such a rapid detection of low-concentration NO2 is applicable in most scenarios. These results provide a reliable, compatible, and promising solution for chemical and biological sensing of gas or liquid-phased substances in hollow-core fibers.

DOI:10.1016/j.snb.2024.135350 [Paper Link]

Corresponding authors

-Xin Jiang, Email: xin.jiang@r-cals.com

Title

Ultrahigh Transverse Mode Purity by Enhanced Modal Filtering in Double-clad Single-ring Hollow-core Photonic Crystal Fiber

Abstract

Maintaining high fundamental mode purity in low-loss single-ring hollow-core photonic crystal fiber remains a key challenge. Here a double-clad anti-resonant-reflecting design is reported that, through modal filtering, provides high suppression of higher-order modes while maintaining a low-loss fundamental mode. The structure consists of a ring of six thin-walled capillaries fused to the inner wall of a thicker-walled capillary that is in turn fused at a single point to the silica outer cladding. Greater than 40 dB m−1 suppression of higher order modes over a 6 nm wide window whose central wavelength can be tuned by adjusting the gas pressure is observed. The novel design paves the way to practical applications of such fibers in high-quality laser beam delivery and low-noise optical-signal transmission.

DOI:10.1002/lpor.202301111 [Paper Link]

Corresponding authors

-Jiapeng Huang, Email: jiapeng.huang@r-cals.com

-Xin Jiang, Email: xin.jiang@r-cals.com

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Continuous Tuning of Pulse Parameters in a Soliton Fiber Laser by Adjusting the Effect of Nonlinear Polarization Rotation

Abstract

We demonstrate that through inserting a short length of highly birefringent small-core photonic crystal fiber (Hi-Bi SC-PCF) into a soliton fiber laser, the nonlinear polarization rotation effect in this laser can be manipulated, leading to continuous tuning of the output pulse parameters. In experiments, we observed that by adjusting the polarization state of light launched into the Hi-Bi SC-PCF and varying the cavity attenuation, the laser spectral width can be continuously tuned from ∼7.1 to ∼1.7 nm, corresponding to a pulse-width-tuning range from ∼350 fs to ∼1.56 ps. During the parameter tuning, the output pulses strictly follow the soliton area theory, giving an almost constant time–bandwidth-product of ∼0.31. This soliton fiber laser, being capable of continuous parameter tuning, could be applied as the seed source in ultrafast laser systems and may find some applications in nonlinear-optics and soliton-dynamics experiments.

DOI:10.1364/OL.509981 [Paper Link]

Corresponding authors

-Wenbin He, Email: wenbin.he@r-cals.com

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Experimental Studies on the Core-structure Dependence of Backward Brillouin Gain in Solid-core Photonic Crystal Fibers

Abstract

Stimulated Brillouin scattering (SBS) in solid-core photonic crystal fibers (PCFs) differs significantly from that in standard optical fibers due to the tight confinement of both optical and acoustic fields in their µm-sized fiber cores, as resultantly evident in their Brillouin gain spectra. Despite many theoretical studies based on either simplified models or numerical simulations, the structural dependency of Brillouin gain spectra in small-core PCFs has not been characterized comprehensively using PCFs with elaborated parameter controls. In this work we report a comprehensive characterization on the core-structure dependences of backward SBS effects in solid-core PCFs that are drawn with systematically varied core-diameter, revealing several key trends of the fiber Brillouin spectrum in terms of its gain magnitude, Brillouin shift and multi-peak structure, which have not been reported in detail previously. Our work provides some practical guidance on PCF design for potential applications like Brillouin fiber lasers and Brillouin fiber sensing.

DOI:10.1364/OE.500633 [Paper Link]

Corresponding authors

-Wenbin He, Email: wenbin.he@r-cals.com

-Meng Pang, Email: pangmeng@siom.ac.cn

Title

Enhancement of Blue and Ultraviolet Components in PCF-based Supercontinuum Generation Through Intermodal Dispersive Wave Radiation

Abstract

Broadband supercontinuum (SC) light sources, generated through nonlinear effects in solid-core photonic crystal fibers (PCFs), have been widely used in spectroscopy, metrology and microscopy, leading to great application successes. The short-wavelength extension of such SC sources, being a longstanding challenge, is a subject of intense studies over the past two decades. However, the exact mechanism of the blue and ultraviolet light generation, especially for some resonance spectral peaks in the short-wavelength regime, has not yet been fully understood. Here, we demonstrate that the effect of intermodal dispersive-wave radiation, resulting from phase matching between pump pulses at fundamental optical mode and packets of linear waves at some high-order modes propagating in the PCF core, might be one of critical mechanisms that can result in some resonance spectral components with wavelengths much shorter than that of the pump light. We observed in the experiment that several spectral peaks resided in the blue and ultraviolet regimes of the SC spectrum, whose central wavelengths can be tuned by varying the PCF-core diameter. These experimental results can be well interpreted using the inter-modal phase-matching theory, providing some useful insights into the SC generation process.

DOI:10.1364/OL.488134 [Paper Link]

Corresponding authors

-Meng Pang, Email: meng.pang@r-cals.com

-Xin Jiang, Email: xin.jiang@r-cals.com

Title

Highly Stable, Flexible Delivery of Microjoule-level Ultrafast Pulses in Vacuumized Anti-resonant Hollow-core Fibers for Active Synchronization

Abstract

We demonstrate the stable and flexible light delivery of multi-microjoule, sub-200-fs pulses over a ~10-m-long vacuumized anti-resonant hollow-core fiber (AR-HCF), which was successfully used for high-performance pulse synchronization. Compared with the pulse train launched into the AR-HCF, the transmitted pulse train out of the fiber exhibits excellent stabilities in pulse power and spectrum, with pointing stability largely improved. The walk-off between the fiber-delivery and the other free-space-propagation pulse trains, in an open loop, was measured to be < 6 fs root mean square (rms) over 90 minutes, corresponding to a relative optical-path variation of < 2×10−7. This walk-off can be further suppressed to ~2 fs rms simply by using an active control loop, highlighting the great application potentials of this ARHCF setup in large-scale laser and accelerator facilities.

DOI:10.1364/OL.486899 [Paper Link]

Corresponding authors

-Meng Pang, Email: meng.pang@r-cals.com

-Xin Jiang, Email: xin.jiang@r-cals.com

Title

Characterization and Manipulation of Temporal Structures of Dispersive Waves in a Soliton Fiber Laser

Abstract

Dispersive waves (DWs) are ubiquitous in nonlinear optical systems that host optical solitons. In particular, DWs in soliton fiber lasers have attracted continuous interest over the past decades since they are closely related to laser soliton instabilities. Meanwhile, intra-cavity DWs also play important roles in solion interactions. While previous studies mostly focused on their spectral properties, characterizations and manipulations of the intra-cavity DWs in the time domain remain unexplored. Here, we report the experimental studies on temporal structures of intra-cavity DWs, unveiling their exponentially-decaying profiles which can be manipulated by varying cavity parameters, following a simple analytic model. We also studied the evolution dynamics of the intra-cavity DWs under abrupt cavity parameter variations. We observed that both the amplitude and the width of the DW waveform went through variations as the pump power was changed, while their evolution trajectories followed intimately that of the soliton energy. These results provide insights into the DW emission mechanism in mode-locked lasers, and the control methods of intra-cavity DWs may find potential applications in the fields of ultrafast pulse generation and soliton dynamics.

DOI:10.1109/JLT.2022.3224564 [Paper Link]

Corresponding authors

- Wenbin He, Email: wenbin.he@r-cals.com

- Meng Pang, Email: pangmeng@siom.ac.cn

- Yunxin Leng, Email: lengyuxin@siom.ac.cn