Anisotropic Fracture of Two-Dimensional Ta2NiSe5.

Anisotropic two-dimensional materials present a diverse range of physical characteristics, making them well-suited for applications in photonics and optoelectronics. While mechanical properties play a crucial role in determining the reliability and efficacy of 2D material-based devices, the fracture behavior of anisotropic 2D crystals remains relatively unexplored. Toward this end, we herein present the first measurement of the anisotropic fracture toughness of 2D Ta2NiSe5 by microelectromechanical system-based tensile tests. Our findings reveal a significant in-plane anisotropic ratio (∼3.0), accounting for crystal orientation-dependent crack paths. As the thickness increases, we observe an intriguing intraplanar-to-interplanar transition of fracture along the a-axis, manifesting as stepwise crack features attributed to interlayer slippage. In contrast, ruptures along the c-axis surprisingly exhibit persistent straightness and smoothness regardless of thickness, owing to the robust interlayer shear resistance. Our work affords a promising avenue for the construction of future electronics based on nanoribbons with atomically sharp edges.

Molecular Design of Fully Nonfused Acceptors for Efficient Organic Photovoltaic Cells.

The nonfused thiophene-benzene-thiophene (TBT) unit offers advantages in obtaining low-cost organic photovoltaic (OPV) materials due to its simple structure. However, OPV cells, including TBT-based acceptors, exhibit significantly lower energy conversion efficiencies. Here, we introduce a novel approach involving the design and synthesis of three TBT-based acceptors by substituting different position-branched side chains on the TBT unit. In comparison to TBT-10 and TBT-11, TBT-13, which exclusively incorporates α-position branched side chains with a large steric hindrance, demonstrates a more planar and stable conformation. When blended with the donor PBQx-TF, TBT-13-based blend film achieves favorable π-π stacking and aggregation characteristics, resulting in excellent charge transfer performance in the corresponding device. Due to the simultaneous enhancements in short-circuit current density and fill factor, the TBT-13-based OPV cell obtains an outstanding efficiency of 16.1%, marking the highest value for the cells based on fully nonfused acceptors. Our work provides a practical molecular design strategy for high-performance and low-cost OPV materials.

Preliminary study on the diagnosis of NK stress based on the puncture mechanical characteristics of cucumber stem.

To investigate the relationship between stem puncture mechanical characteristics and NK stress diagnosis, the microstructure, surface morphology, cellulose and lignin content, puncture mechanical characteristics, and epidermal cell morphology of cucumber stems were measured herein. The results indicated that the middle stem, which had a diameter of approximately 7000 µm, was more suitable for puncturing due to its lower amount of epidermal hair, and its gradual regularity in shape. Further, the cucumber stems were protected from puncture damage due to their ability to rapidly heal within 25 h.. The epidermal penetration of the cucumber stems increased with the increase in cellulose and lignin, though cellulose played a more decisive role. The epidermal break distance increased with an increase in N application and decreased with an increase in K+ application, but the change in intercellular space caused by K+ supply was the most critical factor affecting the epidermal break distance. In addition, a decrease in K+ concentration led to a decrease in epidermal brittleness, whereas the factors affecting epidermal toughness were more complex. Finally, we found that although the detection of epidermal brittleness and toughness on nutrient stress was poor under certain treatment, the puncture mechanical characteristics of the stem still had a significant indicative effect on N application rate. Therefore, elucidating of the relationship between the puncture mechanical characteristics of the stems and crop nutritional stress is not only beneficial for promoting stem stress physiology research but also for designing on-site nutritional testing equipment in the future.

Low repetition rate 915†nm figure-9 ultrafast laser with all-fiber structure.

The advent of optical metrology applications has necessitated the development of compact, reliable, and cost-effective picosecond lasers operating around 900 nm, specifically catering to the requirements of precise ranging. In response to this demand, our work introduces an innovative solution-an all-fiber, all-polarization-maintaining (PM) figure-9 mode-locked laser operating at 915 nm. The proposed figure-9 Nd-doped fiber laser has a 69.2 m long cavity length, strategically designed and optimized to yield pulses with a combination of high pulse energy and low repetition rate. The laser can generate 915 nm laser pulses with a pulse energy of 4.65 nJ, a pulse duration of 15.2 ps under the repetition rate of 3.05 MHz. The 1064 nm amplified spontaneous emission (ASE) is deliberately filtered out, in order to prevent parasitic lasing and increase the spectral proportion of the 915 nm laser. The all-PM fiber configuration of this laser imparts exceptional mode-locking performance and environmental robustness, which is confirmed by long-term output power and spectral stability test. This compact and long-term reliable fiber laser could be a promising light source for applications like inter-satellite ranging.

Single-frequency DBR lasing by integrating FBGs into germanium-free photosensitive highly Yb3+-doped silica fibers.

Monolithic distributed Bragg reflector (DBR) cavity which directly integrates fiber Bragg gratings (FBGs) into the photosensitive RE-doped fibers is a promising configuration in constructing compact and efficient single frequency fiber lasers (SFFLs). Yet, the doping level of rare-earth (RE) ions has generally to be sacrificed in the classical Ge-photosensitized RE-doped silica fibers because of the dramatic refractive index increase caused by the introduction of Ge. Here, we demonstrate an approach to realize the trade-off between photosensitivity and RE doping concentration. We validate that the addition of a small amount of cerium (0.37wt.%) instead of Ge could photosensitize Yb3+-doped silica fiber (YDF), while maintaining fiber numerical aperture (NA) at 0.12 under a high 2.5-wt.% Yb doping level. Based on the short monolithic DBR cavity constructed by this germanium-free photosensitive highly YDF, a 1064 nm fiber laser with a 48.6% slope efficiency and an over 200 mW power on two orthogonally polarized modes could be realized. Further stable and linear-polarized 1064 nm SFFL is also demonstrated in a designed monolithic polarization maintaining cavity with an output power of 119 mW and an efficiency of 26.4%. Our results provide an alternative way to develop photosensitive highly RE-doped fibers towards monolithic laser cavity application.

Diagnostic accuracy and cellular origin of pleural fluid CXCR3 ligands for tuberculous pleural effusion.

BACKGROUND: Pleural biomarkers represent potential diagnostic tools for tuberculous pleural effusion (TPE) due to their advantages of low cost, short turnaround time, and less invasiveness. This study evaluated the diagnostic accuracy of two CXCR3 ligands, C-X-C motif chemokine ligand 9 (CXCL9) and CXCL11, for TPE. In addition, we investigated the cellular origins and biological roles of CXCL9 and CXCL11 in the development of TPE. METHODS: This double-blind study prospectively enrolled patients with undiagnosed pleural effusion from two centers (Hohhot and Changshu) in China. Pleural fluid on admission was obtained and levels of CXCL9 and CXCL11 were measured by an enzyme-linked immunosorbent assay (ELISA). The receiver operating characteristic (ROC) curve and the decision curve analysis (DCA) were used to evaluate their diagnostic accuracy and net benefit, respectively. THP-1 cell-derived macrophages were treated with Bacillus Calmette-Guérin (BCG), and quantitative real-time PCR (qRT-PCR) and ELISA were used to determine the mRNA and protein levels of CXCL9 and CXCL11. The chemoattractant activities of CXCL9 and CXCL11 for T helper (Th) cells were analyzed by a transwell assay. RESULTS: One hundred and fifty-three (20 TPEs and 133 non-TPEs) patients were enrolled in the Hohhot Center, and 58 (13 TPEs and 45 non-TPEs) were enrolled in the Changshu Center. In both centers, we observed increased CXCL9 and CXCL11 in TPE patients. The areas under the ROC curves (AUCs) of pleural CXCL9 and CXCL11 in the Hohhot Center were 0.70 (95 % CI: 0.55-0.85) and 0.68 (95 % CI: 0.52-0.84), respectively. In the Changshu Center, the AUCs of CXCL9 and CXCL11 were 0.96 (95 % CI: 0.92-1.00) and 0.97 (95 % CI: 0.94-1.00), respectively. The AUCs of CXCL9 and CXCL11 decreased with the advancement of age. The decision curves of CXCL9 and CXCL11 showed net benefits in both centers. CXCL9 and CXCL11 were upregulated in BCG-treated macrophages. Pleural fluid from TPE and conditioned medium from BCG-treated macrophages were chemotactic for Th cells. Anti-CXCL9 or CXCL11 neutralizing antibodies could partly block the chemotactic activity. CONCLUSIONS: Pleural CXCL9 and CXCL11 are potential diagnostic markers for TPE, but their diagnostic accuracy is compromised in elderly patients. CXCL9 and CXCL11 can promote the migration of peripheral Th cells, thus representing a therapeutic target for the treatment of TPE.

Er-doped silicate fiber amplifiers in the L-band with flat gain.

We demonstrated an efficient way to enhance and flatten the emission cross sections of Er3+ ions at the L-band in the silicate fiber amplifier by increasing Mg2+ (up to 22.5 mol%) with high field strength. High values of Er3+ concentration, lifetime, and L-band emission cross section were achieved in our silicate fibers. Particularly, the flatness at the L-band was achieved to be 0.8 dB, and a high gain coefficient at 1625 nm (4.7 dB/m) was demonstrated by pumping meter-scale Er-silicate fibers. The as-prepared Er-silicate fibers are attractive for the L-band fiber amplifier.

Efficacy and safety of generic pomalidomide plus low-dose dexamethasone in relapsed or refractory multiple myeloma: a multicenter, open-label, single-arm trial.

This multicenter, open-label, single-arm trial (ClinicalTrials.gov, NCT05236621) was conducted to confirm the efficacy and safety of generic pomalidomide plus dexamethasone in Chinese patients with relapsed or refractory multiple myeloma (RRMM). Total 79 eligible RRMM patients were planned to be included. Patients were treated with generic pomalidomide (4 mg daily on days 1-21, orally) and low-dose dexamethasone (40 mg/day on days 1, 8, 15, and 22, orally; 20 mg for patients aged > 75 years) in 28-day cycles until disease progression with a maximum treatment duration of 2 years. The primary endpoint is the overall response rate (ORR) assessed by the independent review committee per the 2016 International Myeloma Working Group guidelines. A total of 85 eligible patients were included in this study from 32 centers in China, with a median age of 62.0 (range, 39-76) years, a median prior line of therapy of 4 (range, 1-16), and 41.2% patients with high-risk cytogenetics. The ORR was 38.8% (95% confidence interval (CI), 28.44-50.01). The disease control rate was 67.1% (95% CI, 56.02-76.87), meanwhile, the median progression-free survival was 5.55 months (95% CI, 3.68-7.52). Among the treatment-related adverse events (TRAEs), infective pneumonia (17.6%) was the most frequent non-hematologic adverse event, while a decrease in neutrophil count (52.9%) was the most common grade ≥ 3 TRAE. The study results indicated that the generic pomalidomide demonstrated consistent efficacy and a safety profile similar to the branded pomalidomide when combined with low-dose dexamethasone in Chinese RRMM patients.Registration number ClinicalTrials.gov NCT05236621, retrospectively registered on February 11, 2022.

Radiomics in cone-beam breast CT for the prediction of axillary lymph node metastasis in breast cancer: a multi-center multi-device study.

OBJECTIVES: To develop a radiomics model in contrast-enhanced cone-beam breast CT (CE-CBBCT) for preoperative prediction of axillary lymph node (ALN) status and metastatic burden of breast cancer. METHODS: Two hundred and seventy-four patients who underwent CE-CBBCT examination with two scanners between 2012 and 2021 from two institutions were enrolled. The primary tumor was annotated in each patient image, from which 1781 radiomics features were extracted with PyRadiomics. After feature selection, support vector machine models were developed to predict ALN status and metastatic burden. To avoid overfitting on a specific patient subset, 100 randomly stratified splits were made to assign the patients to either training/fine-tuning or test set. Area under the receiver operating characteristic curve (AUC) of these radiomics models was compared to those obtained when training the models only with clinical features and combined clinical-radiomics descriptors. Ground truth was established by histopathology. RESULTS: One hundred and eighteen patients had ALN metastasis (N + (≥ 1)). Of these, 74 had low burden (N + (1~2)) and 44 high burden (N + (≥ 3)). The remaining 156 patients had none (N0). AUC values across the 100 test repeats in predicting ALN status (N0/N + (≥ 1)) were 0.75 ± 0.05 (0.67~0.93, radiomics model), 0.68 ± 0.07 (0.53~0.85, clinical model), and 0.74 ± 0.05 (0.67~0.88, combined model). For metastatic burden prediction (N + (1~2)/N + (≥ 3)), AUC values were 0.65 ± 0.10 (0.50~0.88, radiomics model), 0.55 ± 0.10 (0.40~0.80, clinical model), and 0.64 ± 0.09 (0.50~0.90, combined model), with all the ranges spanning 0.5. In both cases, the radiomics model was significantly better than the clinical model (both p < 0.01) and comparable with the combined model (p = 0.56 and 0.64). CONCLUSIONS: Radiomics features of primary tumors could have potential in predicting ALN metastasis in CE-CBBCT imaging. CLINICAL RELEVANCE STATEMENT: The findings support potential clinical use of radiomics for predicting axillary lymph node metastasis in breast cancer patients and addressing the limited axilla coverage of cone-beam breast CT. KEY POINTS: • Contrast-enhanced cone-beam breast CT-based radiomics could have potential to predict N0 vs. N + (≥ 1) and, to a limited extent, N + (1~2) vs. N + (≥ 3) from primary tumor, and this could help address the limited axilla coverage, pending future verifications on larger cohorts. • The average AUC of radiomics and combined models was significantly higher than that of clinical models but showed no significant difference between themselves. • Radiomics features descriptive of tumor texture were found informative on axillary lymph node status, highlighting a higher heterogeneity for tumor with positive axillary lymph node.

BF3·OEt2 Catalyzed Cascade [4 + 2] Benzannulation of Vinyloxiranes with Coumarins to Construct Benzocoumarin Derivatives.

A BF3·OEt2-catalyzed cascade cyclization reaction of vinyloxirane with coumarin is described, affording the benzocoumarin derivatives with moderate to excellent yields (72-92%). The reaction demonstrates exceptional substrate tolerance and has been extensively explored for its potential in drug development, including scale-up experiments, functional group transformations, and screening of the products for anticancer activity. Moreover, the reaction mechanism has been rigorously validated through intermediate trapping and control experiments. Additionally, this reaction represents the uncommon nonmetal catalyzed intermolecular cyclization of vinyloxiranes.

Surgical treatment of acromioclavicular joint dislocation of Rockwood III/IV: a retrospective study on clavicular hook plate versus arthroscopic TightRope loop titanium button.

PURPOSE: To compare the clinical efficacy of arthroscopic TightRope loop titanium button and clavicular hook plate in the treatment of acromioclavicular joint (ACJ) dislocation of Rockwood III/IV. METHODS: A retrospective analysis of patients with ACJ dislocation in our hospital from January 2018 to December 2020 was conducted. The patients were assigned to be treated with arthroscopic TightRope loop titanium button (TR group) or clavicular hook plate (HP group). The preoperative, intraoperative and postoperative data and imaging findings of the two groups were compared. RESULTS: A total of 58 eligible patients were enrolled in this study. Compared with HP group, TR group had shorter incision length and less blood loss during operation. Postoperative follow-up ranged from 12 to 24 months (mean 15.4 months). At 6 months and 12months postoperatively, compared with HP group, TR group had lower VAS and higher CMS, and the difference was statistically significant. At 12 months postoperatively, compared with HP group, TR group had lower ACJ gap and coracoclavicular joint(CCJ) distance, and the difference was statistically significant.In HP group, there were 3 cases of subacromial impact, 1 case of redislocation, 2 cases of traumatic arthritis and 2 cases of wound infection. There was 1 case of redislocation in TR group. CONCLUSIONS: Compared with clavicular hook plate, arthroscopic TightRope loop titanium button is minimally invasive, safe and effective in the treatment of ACJ dislocation, and has a good trend in clinical application.

Single-Incision Laparoscopic Cholecystectomy Using a Set of Novel Needle Instruments.

BACKGROUND: Although the technique of single-incision laparoscopic cholecystectomy (SILC) has improved remarkably, problems such as limited exposure and instrument collision persist. We describe a new SILC technique that uses a set of specially-designed needle instruments. METHODS: Fifty-six patients with benign gallbladder disease underwent SILC using the newly-designed needle assembly instruments (NAIs). The NAIs comprise an needle assembly exposing hook for operative field exposure and an needle assembly electrocoagulation hook for dissection. During the operation, the NAIs were assembled and disassembled before and after gallbladder removal within the abdominal cavity. The operative efficacy and postoperative complications of this procedure were evaluated. RESULTS: SILC was completed successfully in 52 cases, and four cases (7.14%) required an additional trocar. There were no conversions to open surgery. The mean operative time was 48.2 ± 21.8 min, and the mean operative bleeding volume was 10.5 ± 12.5 mL. Minor postoperative complications occurred in 3 cases, including 2 cases of localized fluid accumulation in the abdominal cavity and 1 case of pulmonary infection, and all of them recovered after conservative treatment. There was no occurrence of bile leak, abdominal bleeding, bile duct injury and incisional hernia. The medical cost of each case was saved by approximately $200. The abdominal scars produced by the needle instruments were negligible. CONCLUSION: NAIs can make SILC safer, more convenient, and less expensive.

Pyrrole-Based Fully Non-fused Acceptor for Efficient and Stable Organic Solar Cells.

Organic solar cells (OSCs) are still suffering from the low light utilization and unstable under ultraviolet irradiation. To tackle these challenges, we design and synthesize a non-fused acceptor based on 1-(2-butyloctyl)-1H-pyrrole as π-bridge unit, denoted as GS70, which serves as active layer in the front-cell for constructing tandem OSCs with a parallel configuration. Benefiting from the well-complementary absorption spectra with the rear-cell, GS70-based parallel tandem OSCs exhibit an improved photoelectron response over the range between 600-700 nm, yielding a high short-circuit current density of 28.4 mA cm-2. The improvement in light utilization translates to a power conversion efficiency of 19.4 %, the highest value among all parallel tandem OSCs. Notably, owing to the intrinsic stability of GS70, the manufactured parallel tandem OSCs retain 84.9 % of their initial PCE after continuous illumination for 1000 hours. Overall, this work offers novel insight into the molecular design of low-cost and stability non-fused acceptors, emphasizing the importance of adopting a parallel tandem configuration for achieving efficient light harvesting and improved photostability in OSCs.

Bendamustine in the treatment of patients with indolent non-Hodgkin lymphoma refractory or relapse to rituximab treatment: An open-label, single-agent, multicenter study in China.

BACKGROUND: The optimal treatment strategy for refractory or relapse (R/R) indolent non-Hodgkin lymphoma (iNHL) has not been fully identified. This study aims to investigate the efficacy and tolerance of bendamustine hydrochloride developed in native Chinese corporation in the treatment of patients with R/R iNHL. METHODS: A total of 101 patients from 19 centers were enrolled in this study from July 2016 to February 2019. Bendamustine hydrochloride (120 mg/m2 ) was given on days 1 and 2 of each 21-day treatment cycle for six planned cycles or up to eight cycles if tolerated. Parameters of efficacy and safety were analyzed. RESULTS: The median age of the patients was 53.44 (range, 24.4-74.6) years old. A total of 56 (55.44%) patients completed at least six treatment cycles, and the relative dose intensity was 93.78%. The overall response rate was 72.28%, and the median duration of response was 15.84 months (95% confidence interval [CI], 13.77-27.48 months). Median progression-free survival was 16.52 months (95% CI, 14.72-23.41 months), and the median overall survival was not reached. Grade 3 or 4 hematologic toxicities included neutropenia (77.22%), thrombocytopenia (29.70%), and anemia (15.84%). The most frequent nonhematologic adverse events (any grade) included nausea, vomiting, fatigue, fever, decreased appetite, and weight loss. Seven patients died during the trial, and four cases may be related to the investigational drug. CONCLUSIONS: This study reveals that bendamustine hydrochloride is a feasible treatment option for the indolent B-cell non-Hodgkin lymphoma patient who has not remitted or relapsed after treatment with rituximab. All adverse events were predictable and manageable.

Bufalin targeting BFAR inhibits the occurrence and metastasis of gastric cancer through PI3K/AKT/mTOR signal pathway.

Gastric cancer (GC) is the most common malignant tumor of digestive system. Bufalin extracted from Venenum Bufonis is one of the most effective anticancer monomers, which has been proved to play anticancer roles in a variety of cancers such as ovarian cancer, prostate cancer and neuroblastoma. However, there are few studies on bufalin in GC, and lack of clear targets. The effect of bufalin on the proliferation and migration of GC cells was detected by CCK-8, scratch wound healing assay, transwell assay and Western blotting. The potential direct interaction proteins of bufalin were screened by human proteome microarray containing 21,838 human proteins. The target protein was determined by bioinformatics, and the binding sites were predicted by molecular docking technique. Biological experiments in vitro and in vivo were conducted to verify the effect of bufalin directly interaction protein and the mechanism of bufalin targeting the protein to inhibit the development of GC. The results showed that bufalin inhibited the proliferation and migration of MKN-45 and HGC-27 GC cell lines in vitro. BFAR, a direct interaction protein of bufalin has several potential binding sites to bufalin. BFAR is highly expressed in GC and promotes the occurrence and metastasis of GC by activating PI3K/AKT/mTOR signal pathway in vitro and in vivo. Bufalin reversed the promoting effect of BFAR on the carcinogenesis and metastasis of GC by down-regulating the expression of BFAR. Our results show that bufalin targeting BFAR inhibits the occurrence and metastasis of GC through PI3K/AKT/mTOR signal pathway. These results provide a new basis for bufalin as a promising drug for the treatment of GC.

The auxin signaling pathway contributes to phosphorus-mediated zinc homeostasis in maize.

Although the interaction between P and Zn has long been recognized in plants, the physiological and molecular mechanisms underlying P and Zn interactions are poorly understood. We show here that P supply decreases the Zn concentration in maize shoots and roots. Compared to +P + Zn (addition of both P and Zn), +P-Zn reduced and -P-Zn increased the total length of 1° lateral roots (LRs). Under +P + Zn, both P and Zn concentrations were lower in the sl1 mutant roots than in wild-type (WT) maize roots, and P accumulation did not reduce the Zn concentration in ll1 mutant roots. Transcriptome profiling showed that the auxin signaling pathway contributed to P-mediated Zn homeostasis in maize. Auxin production and distribution were altered by changes in P and Zn supply. Cytosolic Zn co-localized with auxin accumulation under +P + Zn. Exogenous application of 1-NAA and L-Kyn altered the P-mediated root system architecture (RSA) under Zn deficiency. -P-Zn repressed the expression of miR167. Overexpression of ZmMIR167b increased the lengths of 1° LRs and the concentrations of P and Zn in maize. These results indicate that auxin-dependent RSA is important for P-mediated Zn homeostasis in maize.HighlightAuxin-dependent RSA is important for P-mediated Zn homeostasis in maize.

Efficient three-level continuous-wave and GHz passively mode-locked laser by a Nd3+-doped silicate glass single mode fiber.

Nd3+-doped three-level (4F3/2-4I9/2) fiber lasers with wavelengths in the range of 850-950 nm are of considerable interest in applications such as bio-medical imaging and blue and ultraviolet laser generation. Although the design of a suitable fiber geometry has enhanced the laser performance by suppressing the competitive four-level (4F3/2-4I11/2) transition at ∼1 µm, efficient operation of Nd3+-doped three-level fiber lasers still remains a challenge. In this study, taking a developed Nd3+-doped silicate glass single-mode fiber as gain medium, we demonstrate efficient three-level continuous-wave lasers and passively mode-locked lasers with a gigahertz (GHz) fundamental repetition rate. The fiber is designed using the rod-in-tube method and has a core diameter of 4 µm with a numerical aperture of 0.14. In a short 4.5-cm-long Nd3+-doped silicate fiber, all-fiber CW lasing in the range of 890 to 915 nm with a signal-to-noise ratio (SNR) greater than 49 dB is achieved. Especially, the laser slope efficiency reaches 31.7% at 910 nm. Furthermore, a centimeter-scale ultrashort passively mode-locked laser cavity is constructed and ultrashort pulse at 920 nm with a highest GHz fundamental repetition is successfully demonstrated. Our results confirm that Nd3+-doped silicate fiber could be an alternative gain medium for efficient three-level laser operation.

High ytterbium concentration Yb/Al/P/Ce co-doped silica fiber for 1-µm ultra-short cavity fiber laser application.

We demonstrate a high ytterbium concentration Yb/Al/P/Ce co-doped silica fiber by conventional modified chemical vapor deposition (MCVD) technology and solution doping process. The fiber has a Yb concentration of about 2.5 wt%, and the corresponding core absorption coefficient is measured to be ∼1400 dB/m at 976 nm. The gain coefficient was measured to be approximately 1.0 dB/cm. It is found that the Yb/Al/P/Ce co-doped silica shows a lower photodarkening-induced equilibrium loss of 52 dB/m at 633 nm than the Yb/Al/P co-doped silica fiber of 117 dB/m. Using the heavily Yb3+-doped silica fiber, a compact and robust ultrashort cavity single-frequency fiber laser was achieved with a maximum output power of 75 mW and a linewidth of 14 kHz. Furthermore, a compact passively mode-locked fiber laser (MLFL) with a repetition rate of 1.23 GHz was also proposed using our developed Yb-doped fiber. The laser properties of the proposed lasers were systematically investigated, demonstrating the superior performance of this fiber in terms of photodarkening resistance and ultrashort-cavity laser application. Furthermore, utilizing an all-fiber structure based on silica-based fiber offers the significant advantage of high stability and reliability.

Sub-kHz linewidth 1.6-µm single-frequency fiber laser based on a heavily erbium-doped silica fiber.

We present a single-frequency erbium-doped fiber laser operated at 1608.8 nm using a homemade, heavily erbium-doped silica fiber as gain medium. The laser configuration is based on a ring cavity, which is combined with a fiber saturable absorber to achieve single-frequency operation. The measured laser linewidth is less than 447 Hz and the optical signal-to-noise ratio exceeds 70 dB. The laser exhibits an excellent stability, without any instance of mode-hopping during 1-hour observing. The fluctuations in both wavelength and power were measured to be 0.002 nm and less than 0.09 dB in a 45-minutes period. The laser produces over 14 mW of output power with a slope efficiency of 5.3%, which, to the best of our knowledge, is currently the highest power directly obtained from a single-frequency cavity based on an erbium-doped silica fiber above 1.6 µm.

Extending laser wavelengths to 1630†nm in centimeter-scale Er-phosphate fiber.

The spectral bandwidth of Er-doped fibers limits their lasing wavelength at longer wave band. Here, to the best of our knowledge, we report a broad emission band (1420‒1680 nm) of Er3+ and demonstrate for the first time an Er-phosphate fiber, which supports laser oscillation at the extended wavelengths of 1627 nm and 1630 nm, with the output powers and slope efficiencies of 44 mW/12.5% and 16.5 mW/5.6%, respectively, pumped at 1480 nm. To the best of our knowledge, these are the highest output powers and slope efficiencies at 1627 nm and 1630 nm from an Er3+-doped all-fiber configuration.