High sensitivity distributed dynamic pressure sensor based on dual-linear frequency modulated optical frequency domain reflectometry.

In this Letter, we propose and experimentally demonstrate a highly sensitive distributed dynamic pressure sensor based on a dual-linear frequency modulated optical frequency domain reflectometry (OFDR) and a coating thickness-enhanced single-mode fiber (SMF). A dual-sideband linear frequency modulation (LFM) signal is used to interrogate the sensing fiber, which allows us to obtain a dual-sideband Rayleigh backscattering signal. Due to the opposite slopes of the two LFM sidebands, the Rayleigh backscattering spectra of the two sidebands drift in opposite directions when the fiber is disturbed. By subtracting the frequency shifts of the two spectra, we can double the system's sensitivity. We further enhance the sensitivity by using an SMF with a coating thickness of 200 µm. This results in a pressure sensitivity of 3979 MHz/MPa, a measurement accuracy of 0.76 kPa, and a spatial resolution of 35 cm over a 500 m optical fiber. Our system successfully detected a dynamic pressure change at a sampling rate of 1.25 kHz, demonstrating the sensor's excellent dynamic measuring capabilities.

WHIRLY Proteins, multi-layer regulators linking the nucleus and organelles in developmental and stress-induced senescence of plants.

Plant senescence is an integrated program of plant development that aims to remobilize nutrients and energy from senescing tissues to developing organs under developmental and stress-induced conditions. Upstream in the regulatory network, a small family of single-stranded DNA/RNA-binding proteins known as WHIRLYs occupy a central node, acting at multiple regulatory levels and via trans-localization between the nucleus and organelles. In this review, we summarize the current progress on the role of WHIRLY members in plant development and stress-induced senescence. WHIRLY proteins can be traced back in evolution to green algae. WHIRLY proteins trade off the balance of plant developmental senescence and stress-induced senescence through maintaining organelle genome stability via R-loop homeostasis, repressing the transcription at a configuration condition, recruiting RNA to impact organelle RNA editing and splicing, as evidenced in several species, WHIRLY proteins also act as retrograde signal transducers between organelles and the nucleus through protein modification and stromule or vesicle trafficking. In addition, WHIRLY proteins interact with hormones, ROS and environmental signals to orchestrate cell fate in an age-dependent manner. Finally, prospects for further research and promotion to improve crop production under environmental constraints are highlighted.

The clinical characteristics of subcutaneous and mediastinal emphysema in anti-melanoma differentiation-associated 5 positive dermatomyositis associated with interstitial lung disease.

OBJECTIVES: To investigate the clinical characteristics of subcutaneous emphysema (SE) and mediastinal emphysema (ME) occurring in patients with anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis associated with interstitial lung disease (anti-MDA5-positive DM-ILD). METHODS: In this retrospective study, a total of 117 anti-MDA5-positive DM-ILD patients were admitted to our hospital. All patients underwent an assessment of autoantibodies, serum ferritin levels, and lung high-resolution CT scans. RESULTS: In patients with anti-MDA5-positive DM-ILD, the incidence of SE/ME was found to be 11.1%, which was significantly higher compared to patients with anti-synthetase syndrome (p<0.01). The mortality rate among anti-MDA5-positive DM-ILD patients with SE/ME was significantly higher than those without SE/ME (p=0.0022). There was no statistically significant difference in the occurrence of SE/ME between patients with positive anti-Ro-52 antibodies and those with negative anti-Ro-52 antibodies (p=0.18). Patients with higher serum ferritin levels (1000 ng/ml ≤serum ferritin ≤1500 ng/ml) had a higher likelihood of developing SE/ME compared to patients with lower serum ferritin levels (serum ferritin <500 ng/ml) (p<0.01). Among 13 anti-MDA5-positive DM-ILD patients with SE/ME, six (46.2%) developed SE/ME within 1 month of being diagnosed and 53.8% of patients underwent positive pressure ventilation prior to the onset of SE/ME. CONCLUSIONS: We found that SE/ME is not uncommon in anti-MDA5-positive DM-ILD and is an important factor associated with poor patient prognosis. The occurrence of SE/ME is correlated with high levels of serum ferritin and is not related to anti-Ro-52 antibodies. Rheumatologists should pay close attention to SE/ME caused by positive pressure ventilation in anti-MDA5-positive DM-ILD patients.

Development, validation, and implementation of an ultratrace analysis method for the determination of moenomycin A, in aquatic animal products.

Moenomycin A, an antimicrobial growth promoter widely used as an additive in aquaculture feedstuffs, has been restricted for use in the European Union and China due to its potential risk of promoting resistant strains of pathogenic bacteria and causing residues in aquatic animal products. Although methods for analyzing moenomycin A in feedstuffs have been developed, no established method exists for aquatic matrices. In this study, we present, for the first time, a sensitive and validated high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of moenomycin A in aquatic animal products. Samples were extracted using methanol and purified with the QuEChERS method employing C18 sorbent. The aliquot was dried under a nitrogen stream, reconstituted with methanol-water solvent, and analyzed by HPLC-MS/MS. The developed method exhibited good linearity (r2 > 0.995) over a wide concentration range (1-100 µg/L) and a low limit of detection (1 µg/kg). Average recoveries ranged between 70 and 110% at spiked concentrations of 1, 50, and 100 µg/kg, with associated intra- and inter-day relative standard deviations of 1.25 to 7.32% (n = 6) and 2.91 to 10.08% (n = 3), for different representative aquatic animal production, respectively. To the best of our knowledge, this is the first reported HPLC-MS/MS method for the quantification of moenomycin A in aquatic animal products. The new approach was effectively employed in the analysis of moenomycin A across various aquatic samples.

Integrated physiological, intestinal microbiota, and metabolomic responses of adult zebrafish (Danio rerio) to subacute exposure to antimony at environmentally relevant concentrations.

The available information regarding the impact of antimony (Sb), a novel environmental pollutant, on the intestinal microbiota and host health is limited. In this study, we conducted physiological characterizations to investigate the response of adult zebrafish to different environmental concentrations (0, 30, 300, and 3000 µg/L) of Sb over a period of 14 days. Biochemical and pathological changes demonstrated that Sb effectively compromised the integrity of the intestinal physical barrier and induced inflammatory responses as well as oxidative stress. Analysis of both intestinal microbial community and metabolome revealed that exposure to 0 and 30 µg/L of Sb resulted in similar microbiota structures; however, exposure to 300 µg/L altered microbial communities' composition (e.g., a decline in genus Cetobacterium and an increase in Vibrio). Furthermore, exposure to 300 µg/L significantly decreased levels of bile acids and glycerophospholipids while triggering intestinal inflammation but activating self-protective mechanisms such as antibiotic presence. Notably, even exposure to 30 µg/L of Sb can trigger dysbiosis of intestinal microbiota and metabolites, potentially impacting fish health through the "microbiota-intestine-brain axis" and contributing to disease initiation. This study provides valuable insights into toxicity-related information concerning environmental impacts of Sb on aquatic organisms with significant implications for developing management strategies.

Speech preprocessing and enhancement based on joint time domain and time-frequency domain analysis.

Speech enhancement aims to make noisy speech signals clearer. Traditional time-frequency domain methods struggle to differentiate between speech and noise, leading to a risk of speech distortion. This paper introduces an approach that combines the time domain and time-frequency domain using the W-net module to suppress noise at the front end. The module is an improved version of Wave-U-Net, called TTF-W-Net. We conducted experiments using the TIMIT speech and NOISEX-92 noise datasets to evaluate the enhancement performance achieved by integrating preprocessing networks, specifically Wave-U-Net and our TTF-W-Net, into the baseline methods: Phase, FullSubNet+, and DB-AIAT. Experimental results show that TTF-W-Net outperforms the baseline Wave-U-Net by 15.7% on the PESQ metric and the effect of the network by using our preprocessing method is improved. Consequently, the TTF-W-Net preprocessing Net offers effective speech enhancement.

[Numerical study of the effect of geometrical parameters of straight impellers on the flow and hemolysis performance of centrifugal blood pumps].

Red blood cells are destroyed when the shear stress in the blood pump exceeds a threshold, which in turn triggers hemolysis in the patient. The impeller design of centrifugal blood pumps significantly influences the hydraulic characteristics and hemolytic properties of these devices. Based on this premise, the present study employs a multiphase flow approach to numerically simulate centrifugal blood pumps, investigating the performance of pumps with varying numbers of blades and blade deflection angles. This analysis encompassed the examination of flow field characteristics, hydraulic performance, and hemolytic potential. Numerical results indicated that the concentration of red blood cells and elevated shear stresses primarily occurred at the impeller and volute tongue, which drastically increased the risk of hemolysis in these areas. It was found that increasing the number of blades within a certain range enhanced the hydraulic performance of the pump but also raised the potential for hemolysis. Moreover, augmenting the blade deflection angle could improve the hemolytic performance, particularly in pumps with a higher number of blades. The findings from this study can provide valuable insights for the structural improvement and performance enhancement of centrifugal blood pumps.

Comprehensive exploration of the involvement of cuproptosis in tumorigenesis and progression of neuroblastoma.

BACKGROUND: Copper-induced cell death, or "cuproptosis," as an apoptotic process, has recently received much attention in human diseases. Recent studies on cuproptosis have provided novel insights into the pathogenesis of various diseases, especially cancers. However, the association between neuroblastoma (NB) and cuproptosis in terms of their clinical outcomes, tumorigenesis, and treatment response remains unclear. METHODS: To determine the role of cuproptosis in NB tumorigenesis and progression, this study employed a systematic technique to explore the characteristic patterns of 10 key cuproptosis-related genes (CUGs) in NB. Consensus clustering analysis of the TARGET and GEO databases divided the NB patients into two subgroups that showed different clinicopathological attributes, molecular patterns, survival outcomes, disease-associated pathways, tumor immune microenvironment (TIME) features, and treatment responses. Moreover, a cuproptosis scoring scheme was established, which divided the patients with NB into two groups with high scores and low scores as per the median score. Furthermore, this research developed a nomogram and risk signature on the basis of this cuproptosis score to better elucidate its function in predicting NB prognosis. In vitro experiments were carried out using Transwell Assay, HLECs tube formation assay, Colony formation assay, Western Blotting Assay, Immunohistochemical (IHC) Staining, Immunofluorescence (IF) Staining and Flow Cytometry Analysis. RESULTS: The results demonstrated that the established cuproptosis score and prediction model could effectively distinguish between the individuals in low and high-risk groups and had a high predictive value. Lastly, bioinformatics analysis and in vitro experiments enabled the identification of PDHA1, a key CUG, which was involved in both DNA replication-related pathways and the cell cycle. It was also associated with tumorigenesis and progression of NB. CONCLUSION: Cuproptosis, especially PDHA1, play a crucial role in the TIME characteristics, tumor progression, and long-term prognosis of NB. The patterns of cuproptosis assessed in this research may improve the understanding of the overall concept of NB tumorigenesis, thus facilitating the development of more effective therapeutic interventions.

Silicon supply promotes differences in growth and C:N:P stoichiometry between bamboo and tree saplings.

BACKGROUND: Si can be important for the growth, functioning, and stoichiometric regulation of nutrients for high-Si-accumulating bamboo. However, other trees do not actively take up dissolved silicic acid [Si(OH)4] from the soil, likely because they have fewer or no specific Si transporters in their roots. It is unclear what causes differential growth and C:N:P stoichiometry between bamboo and other trees across levels of Si supply. RESULTS: Si supply increased the relative growth rate of height and basal diameter of bamboo saplings, likely by increasing its net photosynthetic rate and ratios of N:P. Moreover, a high concentration of Si supply decreased the ratio of C:Si in bamboo leaves due to a partial substitution of C with Si in organic compounds. We also found that there was a positive correlation between leaf Si concentration and its transpiration rate in tree saplings. CONCLUSIONS: We demonstrated that Si supply can decrease the ratio of C:Si in bamboo leaves and increase the ratio of N:P without altering nutrient status or the N:P ratio of tree saplings. Our findings provide experimental data to assess the different responses between bamboo and other trees in terms of growth, photosynthesis, and C:N:P stoichiometry. These results have implications for assessing the growth and competition between high-Si-accumulating bamboo and other plants when Si availability is altered in ecosystems during bamboo expansion.

Evaluating the value of superoxide dismutase in anti-MDA5-positive dermatomyositis associated with interstitial lung disease.

OBJECTIVE: This study aimed to investigate the relationship between serum superoxide dismutase (SOD) and interstitial lung disease (ILD) among patients with anti-melanoma differentiation-associated gene 5 antibody (MDA5)-positive DM. METHOD: In this retrospective study, serum SOD of 90 health check-ups were tested in our hospital. A total of 94 hospitalized patients with anti-MDA5-positive DM had ILD. Their serum SOD, serum ferritin and autoantibody levels were determined and lung high-resolution CT was performed. RESULTS: The serum SOD level was significantly lower in the anti-MDA5-positive DM group compared with the control group. The SOD level was significantly lower in patients positive for both anti-MDA5 antibodies and anti-Ro-52 antibodies than in those positive for only anti-MDA5 antibodies before treatment. The SOD level was significantly lower in the higher serum ferritin group compared with the lower serum ferritin group before treatment. After treatment, the serum SOD level decreased in patients with exacerbation of ILD, while it increased in those with alleviated ILD. The SOD level was significantly lower in the death group than in the survival group before treatment. CONCLUSIONS: In patients with anti-MDA5-positive DM, the low SOD level before treatment indicated the presence of oxidative stress in the disease; the serum SOD level was affected by anti-Ro-52 antibodies and ferritin; there is a close relationship between serum SOD level and ILD among patients with anti-MDA5-positive DM, suggesting that SOD might serve as an effective indicator to evaluate the changes in ILD in these patients; and the low SOD level is an important indicator of poor prognosis in these patients, which deserves attention from rheumatologists.

Kerr soliton frequency comb generation by tuning the coupling coefficient in coupled nonlinear microcavities.

Kerr soliton frequency comb generation in nonlinear microcavities with compact configurations are promising on-chip sources. Current Kerr comb generation by using a single microcavity with a tunable CW pump laser or high-power femtosecond pulse pump are difficult to be integrated on chip. In this paper, we propose an on-chip soliton comb generation scheme by tuning the coupling coefficient of two coupled microcavities instead of tuning the wavelength of the cw pump laser or using a pulsed pump laser in a single microcavity. The two microcavities are assumed to be identical. We showed by numerical simulation that Kerr comb generation is possible in both the blue and red detuned regions of the main microcavity in the coupled cavity system. We further found that the range and boundary of the soliton generation region of the couple microcavities depend on the coupling coefficient between the coupled cavities. To ensure that the modes being coupled have identical optical paths, we designed a Sagnac loop structure which couples the clockwise and counterclockwise modes in a single microcavity and demonstrated Kerr comb generation in both the blue and red detuned regions by tuning the coupling coefficient. The proposed Kerr comb generation scheme can be utilized for chip-scale integrated soliton comb sources, which will contribute to the development of on-chip applications.

Coherent OTDR with large dynamic range based on double-sideband linear frequency modulation pulse.

Rayleigh scattering-based distributed optical fiber sensors with long sensing distance and large dynamic range are highly desired for application scenarios such as vehicle tracking, structure health monitoring, and geological survey. To enlarge the dynamic range, we propose a coherent optical time domain reflectometry (COTDR) based on double-sideband linear frequency modulation (LFM) pulse. By utilizing I/Q demodulation, both the positive and negative frequency band of the Rayleigh backscattering (RBS) signal can be properly demodulated. Consequently, the dynamic range is doubled without increasing the bandwidth of signal generator, photodetector (PD), and oscilloscope. In the experiment, the chirped pulse with 10 µs pulse width and 498 MHz frequency sweeping range is launched into the sensing fiber. Single-shot strain measurement is achieved over 5 km single-mode fiber with a spatial resolution of 2.5 m and a strain sensitivity of 7.5 pε/H z. A vibration signal with 3.09 µÎµ peak-to-peak amplitude (corresponding to 461 MHz frequency shift) is successfully measured with the double-sideband spectrum, which cannot be properly recovered with the single-sideband spectrum.

Synchronized time lens based temporal magnifier assisted by the phase lock loop.

We propose a synchronized time lens based temporal magnifier for the characterization of an ultrafast pulse, which is assisted by the phase lock loop (PLL) to actively lock the repetition rates of the pump laser and signal laser. A feedback control system combining a proportional-integral (PI) circuit and a piezoelectric transducer (PZT) inside the signal laser cavity is used to synchronize the repetition rates between the pump and signal lights. Benefitting from the PLL technique, the temporal position of the signal pulse remains as the numerical aperture of the time lens system, and therefore it has a high short-time stability for pulse measurement. This synchronized time lens based temporal magnifier can record single-shot pulses within continuous round trips. By engineering the dispersion of the pump, signal, and idler lights, we demonstrate a 200× magnification of the signal pulse. Our technique offers a simple synchronized method in a time lens system for ultrafast temporal characterization, which provides new insights into the observation of the fiber laser dynamics.

Narrow linewidth semiconductor multi-wavelength DFB laser array simultaneously self-injection locked to a single microring resonator.

We experimentally demonstrate a narrow linewidth semiconductor multi-wavelength distributed feedback (DFB) laser array by simultaneously injection locking each laser to the corresponding resonance of a single on-chip microring resonator. The white frequency noises of all the DFB lasers is reduced by more than 40 dB once they are simultaneously injection locked to a single microring resonator with a quality factor (Q-factor) of 2.38 million. Correspondingly, the instantaneous linewidths of all the DFB lasers are narrowed by a factor of 104. In addition, frequency combs originating from non-degenerate four-wave mixing (FWM) between the locked DFB lasers are also observed. Simultaneously injection locking multi-wavelength lasers to a single on-chip resonator may enable the possibilities of integrating a narrow-linewidth semiconductor laser array on a single chip and having multiple microcombs in a single resonator, which are in high demand in wavelength division multiplexing coherent optical communication systems and metrological applications.

Validation of an automatic method for reconstruction, delineation, and measurement of levator hiatus in clinical practice.

OBJECTIVES: To evaluate the concordance between an automatic software program and manual evaluation in reconstructing, delineating, and measuring the levator hiatus (LH) on maximal Valsalva maneuver. METHODS: This was a retrospective study analyzing archived raw ultrasound imaging data of 100 patients underwent transperineal ultrasound (TPUS) examination. Each data were assessed by the automatic Smart Pelvic System software program and manual evaluation. The Dice similarity index (DSI), mean absolute distance (MAD), and Hausdorff distance (HDD) were calculated to quantify delineation accuracy of LH. Agreement between automatic and manual measurement of levator hiatus area was assessed by intraclass correlation coefficient (ICC) and Bland-Altman method. RESULTS: The satisfaction rate of automatic reconstruction was 94%. Six images were recognized as unsatisfactory reconstructed images for some gas in the rectum and anal canal. Compared with satisfactory reconstructed images, DSI of unsatisfactory reconstructed images was lower, MAD and HDD were larger (p = 0.001, p = 0.001, p = 0.006, respectively). The ICC was up to 0.987 in 94 satisfactory reconstructed images. CONCLUSIONS: The Smart Pelvic System software program had good performance in reconstruction, delineation, and measurement of LH on maximal Valsalva maneuver in clinical practice, despite misidentification of the border of posterior aspect of LH due to the influence of gas in the rectum.

Prednisone vs Placebo and Live Birth in Patients With Recurrent Implantation Failure Undergoing In Vitro Fertilization: A Randomized Clinical Trial.

Importance: Implantation failure remains a critical barrier to in vitro fertilization. Prednisone, as an immune-regulatory agent, is widely used to improve the probability of implantation and pregnancy, although the evidence for efficacy is inadequate. Objective: To determine the efficacy of 10 mg of prednisone compared with placebo on live birth among women with recurrent implantation failure. Design, Setting, and Participants: A double-blind, placebo-controlled, randomized clinical trial conducted at 8 fertility centers in China. Eligible women who had a history of 2 or more unsuccessful embryo transfer cycles, were younger than 38 years when oocytes were retrieved, and were planning to undergo frozen-thawed embryo transfer with the availability of good-quality embryos were enrolled from November 2018 to August 2020 (final follow-up August 2021). Interventions: Participants were randomized (1:1) to receive oral pills containing either 10 mg of prednisone (n = 357) or matching placebo (n = 358) once daily, from the day at which they started endometrial preparation for frozen-thawed embryo transfer through early pregnancy. Main Outcomes and Measures: The primary outcome was live birth, defined as the delivery of any number of neonates born at 28 or more weeks' gestation with signs of life. Results: Among 715 women randomized (mean age, 32 years), 714 (99.9%) had data available on live birth outcomes and were included in the primary analysis. Live birth occurred among 37.8% of women (135 of 357) in the prednisone group vs 38.8% of women (139 of 358) in the placebo group (absolute difference, -1.0% [95% CI, -8.1% to 6.1%]; relative ratio [RR], 0.97 [95% CI, 0.81 to 1.17]; P = .78). The rates of biochemical pregnancy loss were 17.3% in the prednisone group and 9.9% in the placebo group (absolute difference, 7.5% [95% CI, 0.6% to 14.3%]; RR, 1.75 [95% CI, 1.03 to 2.99]; P = .04). Of those in the prednisone group, preterm delivery occurred among 11.8% and of those in the placebo group, 5.5% of pregnancies (absolute difference, 6.3% [95% CI, 0.2% to 12.4%]; RR, 2.14 [95% CI, 1.00 to 4.58]; P = .04). There were no statistically significant between-group differences in the rates of biochemical pregnancy, clinical pregnancy, implantation, neonatal complications, congenital anomalies, other adverse events, or mean birthweights. Conclusions and Relevance: Among patients with recurrent implantation failure, treatment with prednisone did not improve live birth rate compared with placebo. Data suggested that the use of prednisone may increase the risk of preterm delivery and biochemical pregnancy loss. Our results challenge the value of prednisone use in clinical practice for the treatment of recurrent implantation failure. Trial Registration: Chinese Clinical Trial Registry Identifier: ChiCTR1800018783.

Genome-wide identification and expression analysis of the SWEET gene family in daylily (Hemerocallis fulva) and functional analysis of HfSWEET17 in response to cold stress.

BACKGROUND: The Sugars Will Eventually be Exported Transporters (SWEETs) are a newly discovered family of sugar transporters whose members exist in a variety of organisms and are highly conserved. SWEETs have been reported to be involved in the growth and development of many plants, but little is known about SWEETs in daylily (Hemerocallis fulva), an important perennial ornamental flower. RESULTS: In this study, 19 daylily SWEETs were identified and named based on their homologous genes in Arabidopsis and rice. Phylogenetic analysis classified these HfSWEETs into four clades (Clades I to IV). The conserved motifs and gene structures showed that the HfSWEETs were very conservative during evolution. Chromosomal localization and synteny analysis found that HfSWEETs were unevenly distributed on 11 chromosomes, and there were five pairs of segmentally duplicated events and one pair of tandem duplication events. The expression patterns of the 19 HfSWEETs showed that the expression patterns of most HfSWEETs in different tissues were related to corresponding clades, and most HfSWEETs were up-regulated under low temperatures. Furthermore, HfSWEET17 was overexpressed in tobacco, and the cold resistance of transgenic plants was much higher than that of wild-type tobacco. CONCLUSION: This study identified the SWEET gene family in daylily at the genome-wide level. Most of the 19 HfSWEETs were expressed differently in different tissues and under low temperatures. Overexpression further suggests that HfSWEET17 participates in daylily low-temperature response. The results of this study provide a basis for further functional analysis of the SWEET family in daylily.

Highly coherent, flat, and broadband time-stretched swept source based on extra-cavity spectral shaping assisted by a booster semiconductor optical amplifier.

We demonstrate a flat broadband time-stretched swept source based on extra-cavity spectral shaping. By adjusting the polarization-dependent gain profile and driving current of the booster optical amplifier (BOA), extra-cavity spectral shaping is optimized to generate output with a 1-dB bandwidth of ∼100 nm, 3-dB bandwidth of ∼140 nm and output power of ∼21.4 mW. The short-term and long-term stabilities are characterized. The average cross correlation of 183,485 round trips is 0.9997 with a standard deviation of 2×10-5, indicating high single-shot spectral similarity and high coherence. The noise floor of relative spectral energy jitter is -141.7 dB/Hz, indicating a high short-term spectral energy stability. The proposed highly stable flat broadband time-stretched swept source is applied to an optical coherence tomography (OCT) system. The axial resolution is 10.8 µm. The proposed swept source can serve as excellent light sources in ultra-fast coherent detection systems for high precision sensing and imaging.

Low bending loss few-mode hollow-core anti-resonant fiber with glass-sheet conjoined nested tubes.

A novel hollow-core anti-resonant fiber (HC-ARF) with glass-sheet conjoined nested tubes that supports five core modes of LP01-LP31 with low mode couplings, large differential group delays (DGDs), and low bending losses (BLs) is proposed. A novel cladding structure with glass-sheet conjoined nested tubes (CNT) is induced for the proposed HC-ARF which can suppress mode couplings between the LP01-LP31 modes and the cladding modes. The higher-order modes (HOMs) which are LP11-LP31 modes also have very low loss by optimizing the radius of the nested tube and the core radius. Moreover, the large effective refractive index differences Δneff between HOMs are all larger than 1 × 10-4 which contributes to a large DGD in the wavelength range from 1.3 to 1.7 µm. The bending loss of the HC-ARF is analyzed and optimized emphatically. Our calculation results show that bending losses of LP01-LP31 modes are all lower than 3.0 × 10-4 dB/m in the wavelength range from 1.4 to 1.61 µm even when the fiber bending radius of the HC-ARF is 6 cm.

Mutual dynamics between synchronous solitons in a bidirectional mode-locked fiber laser.

In this Letter, the mutual dynamics between synchronous solitons in a bidirectional mode-locked fiber laser are studied via dispersive Fourier transform methodology. We explore the spectral evolution and the statistical correlations between solitons with bidirectional propagation, indicating the low and high mutual linear dependences of the spectral energy jitters in stable and breathing mode-locking states, respectively. Moreover, to the best of our knowledge, the oscillating and sliding phase dynamics are experimentally revealed by the interference between bidirectional breathing solitons in ultrafast fiber lasers for the first time. Our findings enrich the understanding of the internal mutual dynamics between bidirectional solitons, which guides the extension of their potential applications, such as Sagnac-effect-based optical sensing.