SEMA7A as a Novel Prognostic Biomarker and Its Correlation with Immune Infiltrates in Breast Cancer.

Background: The role of Semaphorin 7a (SEMA7A) in the initiation and progression of different types of cancerous lesions has been extensively studied. However, the prognostic significance of SEMA7A, specifically in breast cancer (BC), lacks clarity. Methods: We conducted an evaluation on the relationship between SEMA7A and the prognosis, immune invasion and tumor mutation burden in different types of cancer by analyzing data from The Cancer Genome Atlas database. The present study focused on investigating the expression level, mutation, immune correlation and coexpression of SEMA7A in BC, utilizing various databases such as the University of Alabama at Birmingham Cancer data analysis portal, cBioPortal and tumor immune estimation resource. Survival analysis was carried out using the Kaplan-Meier Plotter. Furthermore, we employed the R software package to generate receiver operating characteristic (ROC) curves and nomograms. Notably, P<0.05 was considered to indicate statistical significance. Results: Using pancancer analysis, it has been observed that the expression of SEMA7A is elevated in various types of cancer and is strongly correlated with the prognosis of different cancer types. SEMA7A also exhibits a significant association with the tumor mutation burden of diverse types of cancer. Moreover, SEMA7A displays a notable increase in BC cases, and was indicated to have a substantial association with the abundance of immune infiltration. In-depth survival analysis demonstrated that elevated levels of SEMA7A expression are notably linked to shorter overall survival and distant metastasis-free survival among patients with BC. The efficiency of SEMA7A as a reliable prognostic biomarker for BC has been substantiated by the validation of ROC curves and nomograms. Conclusion: SEMA7A has the potential to function as a prognostic indicator for BC, and its correlation with immune infiltration in BC is significant.

First-principles study of the effect of oxygen vacancy and iridium doping on formaldehyde adsorption on the La2O3(001) surface.

Formaldehyde adsorption on intrinsic La2O3 surface, four-fold coordinated oxygen vacancy (VO4c), six-fold coordinated oxygen vacancy (VO6c), and iridium-doped La2O3(001) surface was studied by the first-principles method. The results show that formaldehyde adsorption on the Ir-doped La2O3(001) surface with VO6c is the strongest because of the directional movement of electrons caused by the interaction of the Ir-5d orbitals and internal oxygen vacancy, wherein the adsorption energy is 3.23 eV. This model showed a significant increase in adsorption energy, indicating that Ir doping improves the formaldehyde adsorption capacity of the La2O3(001) surface. The energy band analysis shows that iridium doping introduces impurity energy levels into the intrinsic La2O3 energy band, which enhances the interaction between the La2O3(001) surface and formaldehyde molecules. Density of state analysis indicated that the adsorption of formaldehyde molecules on the La2O3(001) surface is mainly due to the interaction between the O-2p, C-2p orbitals of formaldehyde and the Ir-5d orbital of iridium atoms. Furthermore, the existence of VO4c and VO6c defects has no effect on the position and shape of the valence and conduction bands. The effects of oxygen vacancy and iridium doping on the optical properties mainly appeared in the low-energy infrared and visible regions, making the O-2p, C-2p orbitals of formaldehyde and the Ir-5d, O-2p orbitals of the La2O3(001) surface become hybridized near the Fermi level and the electronic transition from the valence band to conduction band more likely to occur. The La2O3 material can be used as an ideal photocatalytic material for formaldehyde degradation.

Comprehensive pan­cancer analysis of MTDH for human tumor prognosis and as an immunological biomarker including breast and kidney cancer.

Metadherin (MTDH), initially discovered in primary astrocytes of the human fetus through rapid subtraction hybridization and labeled as astrocyte elevated gene-1, represents a widely recognized oncogene present in multiple types of cancers. However, the role of MTDH in different types of cancer remains unclear. To address this, a comprehensive analysis of MTDH across various types of cancers was conducted by utilizing multiple databases such as The Cancer Genome Atlas. The present analysis discovered that MTDH exhibits differential expression in different types of cancer and is associated with important factors including tumor mutational burden and microsatellite instability. These findings highlighted the significance of MTDH in the tumor microenvironment and its involvement in the development of immune cells in specific cancers. Furthermore, the results of the present study indicated that the expression of MTDH is strongly correlated with clinical prognosis, mutations and immune cell infiltration. MTDH could serve as a potential indicator of patient prognosis and potentially play a role in modulating the immune system. Given its potential as a novel immunological checkpoint, MTDH may be a viable target for tumor immunotherapy.

Association of ADP­ribosylation factor family genes with prognosis and immune infiltration of breast cancer.

Breast cancer (BC) is the most common type of cancer found in women. ADP-ribosylation factors (ARFs) are a group of small proteins that bind to GTP and are involved in controlling different cellular functions. The function and evolution of multiple ARFs in BC have remained to be fully elucidated, despite existing studies on this protein family in Homo sapiens and other species. In the present study, a systematic analysis of ARF expression levels in BC tissues compared to normal breast tissues was performed using data from The Cancer Genome Atlas database. The analysis revealed significantly higher expression of ARFs in BC tissues. In addition, the prognostic significance of ARF1 and ARF3-6 expression levels was assessed in patients with BC. Of note, elevated ARF1 expression was associated with reduced rates of distant metastasis-free survival (DMFS), overall survival (OS) and recurrence-free survival (RFS) in affected individuals. Similarly, patients with high expression levels of ARF3 had lower post-progression survival (PPS) rates. In addition, patients with higher ARF4 expression had worse PPS and patients with high ARF5 expression exhibited lower DMFS. Patients with high ARF6 expression had worse DMFS, OS, RFS and predictive power score values. Furthermore, the expression of ARF was found to be strongly linked to the infiltration of various immune cell types, namely dendritic cells, macrophages, neutrophils, CD8+ T cells and B cells. These significant associations offer a solid foundation for the potential utilization of new therapeutic targets and predictive markers for the treatment of BC.

[Network Meta-analysis of different Chinese medicine injections combined with conventional western medicine in treatment of acute heart failure].

This study aims to evaluate the efficacy and safety of Chinese medicine injection in the treatment of acute heart failure. PubMed, Cochrane Library, EMbase, Web of Science, CNKI, VIP, Wanfang, and SinoMed were searched for the randomized controlled trial(RCT) of Chinese medicine injection combined with conventional western medicines in the treatment of acute heart failure with the time interval from the inception to July 10, 2023. Two researchers independently screened the literature, extracted data, and evaluated the risk of bias in the included studies. Stata 15.1 was used to perform network Meta-analysis. A total of 117 RCTs were included, involving 10 529 patients and 7 Chinese medicine injections: Shenfu Injection, Shenmai Injection, Danhong Injection, Puera-rin Injection, Xinmailong Injection, Shengmai Injection, and Yiqi Fumai Injection. Network Meta-analysis yielded the following results.(1) In terms of improving the total response rate, the surface under the cumulative ranking curve(SUCRA) ranking was Shengmai Injection + conventional western medicine > Danhong Injection + conventional western medicine > Shenmai Injection + conventio-nal western medicine > Shenfu Injection + conventional western medicine > Xinmailong Injection + conventional western medicine > Yiqi Fumai Injection + conventional western medicine > Puerarin Injection + conventional western medicine > conventional western medicine.(2)In terms of reducing brain natriuretic peptide(BNP), the SUCRA ranking was Danhong Injection + conventional western medicine > Xinmailong Injection + conventional western medicine > Yiqi Fumai Injection + conventional western medicine > Shenfu Injection + conventional western medicine > Shenmai Injection + conventional western medicine > Puerarin Injection + conventional wes-tern medicine > Shengmai Injection + conventional western medicine > conventional western medicine.(3)In terms of reducing N-terminal pro-brain natriuretic peptide(NT-proBNP), the SUCRA ranking was Shenmai Injection + conventional western medicine > Yiqi Fumai Injection + conventional western medicine > Xinmailong Injection + conventional western medicine > Shengmai Injection + conventional western medicine > Shenfu Injection + conventional western medicine > Puerarin Injection + conventional western medicine > Danhong Injection + conventional western medicine > conventional western medicine.(4) In terms of improving the left ventricular ejection fraction(LVEF), the SUCRA ranking was Shenmai Injection + conventional western medicine > Xinmailong Injection + conventional western medicine > Shenfu Injection + conventional western medicine > Yiqi Fumai Injection + conventional western medicine > Puerarin Injection + conventional western medicine > Danhong Injection + conventional western medicine > Shengmai Injection + conventional western medicine > conventional western medicine.(5) In terms of decreasing the left ventricular end-diastolic diameter(LVEDD), the SUCRA ranking was Shenmai Injection + conventional western medicine > Shenfu Injection + conventional western medicine=Xinmailong Injection + conventional western medicine > Shengmai Injection + conventional western medicine > Yiqi Fumai Injection + conventional western medicine > conventional western medicine > Puerarin Injection + conventional western medicine.(6) In terms of increasing the 6-min walk trail(6MWT), the SUCRA ranking was Xinmailong Injection + conventional western medicine > Shenfu Injection + conventional western medicine > Shenmai Injection + conventional western medicine > Yiqi Fumai Injection + conventional western medicine > conventional western medicine.(7) In terms of reducing the Minnesota heart failure quality of life scale(MLHFQ) scores, the SUCRA ranking was Xinmailong Injection + conventional western medicine > Shenmai Injection + conventional western medicine > Shenfu Injection + conventional western medicine > conventional western medicine.(8)In terms of safety, the group of Chinese medicine injection combined with conventional western medicine had lower incidence of adverse reactions than the control group. The current evidence shows that combining Chinese medicine injection with conventional western medicine treatment can improve the therapeutic effect on acute heart failure, with high safety. Due to the limited number and quality of included studies, the above conclusions need to be verified by more high-quality studies.

Bioinformatic analysis reveals an association between Metadherin with breast cancer prognosis and tumor immune infiltration.

Breast cancer metastasis and invasion are both promoted by the oncoprotein Metadherin (MTDH). However, the the role of Metadherin in breast cancer progression and its role in the immune microenvironment. Are not clear. A bioinformatic analysis was performed to demonstrate the prognostic value of Metadherin in BC. In the present study, we found that Metadherin is overexpressed in BC and is significantly correlated with individual cancer stage, age, subclasses, menopause and nodal metastasis status. Metadherin overexpression was associated with a significant decrease in OS and DSS. Cox multivariate analysis indicated that Metadherin was an independent negative prognostic indicator for OS and DSS. Moreover, Metadherin hypomethylation status was associated with poor prognosis. A negative correlation was also noted between Metadherin overexpression and the number of plasmacytoid dendritic cells, cluster of differentiation 8+ T cells, and natural killer cells. Association patterns varied with different subtypes. Various associations between Metadherin levels and immune cell surface markers were revealed. A total of 40 groups of BC and adjacent normal breast tissue samples were collected. Metadherin mRNA was detected by PCR, and its expression levels in BC tissues were significantly increased compared with those noted in normal tissues. The expression levels of Metadherin were also measured in normal and BC cell lines, respectively, and similar conclusions were obtained. The Metadherin mRNA levels were knocked down in SK-BR3 and MDA-MB-231 cell lines and the cell proliferative and migratory activities were determined using Cell Counting Kit-8 and scratch assays, respectively. The results indicated that the cell proliferative and migratory abilities were reduced following knockdown of Metadherin expression. Therefore, Metadherin may be considered as a novel prognostic biomarker in BC.

​Efficacy and safety of pyrotinib in combination with albumin­bound paclitaxel for the treatment of HER2­positive advanced breast cancer: A real­world study.

The present study aimed to determine the efficacy and safety of pyrotinib in combination with albumin-bound paclitaxel in patients with HER2-positive advanced breast cancer (ABC). A total of 48 patients diagnosed with HER2-positive ABC were included in the present study, and these patients were prescribed a combination of pyrotinib and albumin-bound paclitaxel in routine clinical practice. During a 21-day cycle, the standard dosage of pyrotinib was 400 mg single dose/day, which was administered orally, and 130 mg/m2/day albumin-bound paclitaxel on days 1, 8 and 15, which was administered by intravenous drip. The primary efficacy endpoint was progression-free survival (PFS) and the secondary efficacy endpoint was overall response rate (ORR), which was defined as the percentage of patients with complete remission or partial remission. Safety indicators were also observed in the present study. The results of the present study demonstrated that the median PFS (mPFS) was 8.1 months for all patients, ranging from 3.3-10.6 months. Patients receiving pyrotinib as second-line therapy exhibited a longer mPFS of 8.5 months compared with those receiving it as third- or higher-line therapy (mPFS, 5.9 months). In 17 patients with brain metastases, mPFS was 7.3 months, ranging from 4.8-10.1 months. The results of the present study also demonstrated that the ORR for the 48 patients was 33.3%. Notably, diarrhea was the most common grade 3-4 adverse event, occurring in 22.9% of patients, followed by neutropenia (6.3%), leukopenia (4.2%) and anemia (4.2%). Collectively, the results of the present study indicated that pyrotinib-based treatment is effective for patients with HER2+ ABC, including those who have previously been treated with trastuzumab. Thus, the combination of pyrotinib with albumin-bound paclitaxel is recommended due to high levels of efficacy, convenience and tolerability.

LPS-pretreatment adipose-derived mesenchymal stromal cells promote wound healing in diabetic rats by improving angiogenesis.

Mesenchymal stem cells (MSCs) play a key role in wound healing, and the advantages of pretreated MSCs in wound healing have previously been reported. In the present study, we investigated the impact of LPS pretreated human adipose-derived MSCs on skin wound healing in diabetic rats. We found that some improvements occurred through improving angiogenesis. Then, we scrutinized the impact of lipopolysaccharide (LPS) treatment on human adipose-derived MSCs in a high-glucose (HG) medium, as an in vitro diabetic model. In vivo findings revealed significant improvements in epithelialization and angiogenesis of diabetic wounds which received LPS pre-MSCs. Particularly, LPS pre-MSCs-treated diabetic wounds reached considerably higher percentages of wound closure. Also, the granulation tissue of these wounds had higher pronounced epithelialization and more vascularization compared with PBS-treated and MSCs-treated diabetic ones by CD31, VEGF, CD90, collagen 1, and collagen 3 immunostaining. Western-blots analyses indicated that LPS pre-MSCs led to the upregulation of vascular endothelial growth factor (VEGF) and DNMT1. In addition, significantly higher cell viability (proliferation/colonie), and elevated VEGF and DNMT1 protein expression were observed when MSCs were treated with LPS (10 ng/ml, 6 h) in HG culture media. Based on these findings, it is suggested that LPS pre-MSCs could promote wound repair and skin regeneration, in some major processes, via the improvement of cellular behaviors of MSCs in the diabetic microenvironment. The beneficial advantages of LPS treated with mesenchymal stem cells on wound healing may lead to establishing a novel approach as an alternative therapeutic procedure to cure chronic wounds in diabetic conditions.

The Value of m5C-Related lncRNAs in the Prognostic Assessment and Immunotherapy of Stomach Adenocarcinoma.

Long noncoding RNAs (lncRNAs) are closely associated with a variety of tumors, including stomach adenocarcinoma (STAD). However, the role of 5-methylcytosine- (m5C-) related lncRNAs in STAD is still uncertain. This study investigated the value of m5C-related lncRNAs in prognostic evaluation and immunotherapy of STAD. STAD transcriptome sequencing data were downloaded from The Cancer Genome Atlas (TCGA) database, and m5C-related lncRNAs were screened by Pearson correlation analysis. A prognostic m5C-related lncRNA signature (m5CRLSig) associated with STAD was established using univariate and multivariate Cox regression analysis. We constructed a prognostic risk model for STAD with six m5C-related lncRNAs. The receiver operating characteristic (ROC) curve was used to examine the predictive efficacy. Univariate and multifactorial Cox regression analysis and principal component analysis (PCA) validated m5CRLSig as an independent factor of STAD prognosis. The clinicopathological characteristics of the model showed higher risk scores for stages II-IV, grade 3, N1-3, and death status. The calibration curve of a nomogram revealed that the nomogram had an excellent predictive function for survival risk. Furthermore, the expression of six m5C-related lncRNAs in STAD and paracancerous tissues was detected by quantitative real-time PCR (qRT-PCR), which verified the feasibility of the m5CRLSig as a prognostic marker for STAD. m5C-related lncRNAs were linked to multiple immune-associated pathways, according to gene set enrichment analysis (GSEA). CIBERSORT analysis indicated that m5CRLSig was involved in immune cell infiltration. Risk score was associated with immune checkpoint gene expression, immune function scores, and chemotherapeutic drug sensitivity. Therefore, m5CRLSig can efficiently assess the prognosis of STAD patients and can be used as a biological marker for immunotherapy.

Effect of Probiotic-Assisted Eradication of cagA+/vacA s1m1 Helicobacter pylori on Intestinal Flora.

Objective: We attempted to evaluate the effects of probiotic-assisted eradication of cytotoxin-associated gene A (cagA)+/vacuolating cytotoxin A (vacA) s1m1 Helicobacter pylori (H. pylori) on the intestinal flora, inflammatory factors, and clinical outcomes. Methods: A total of 180 patients with cagA+/vacA s1m1 H. pylori were randomly divided into two groups. Group A was treated with bismuth quadruple therapy (BQT). Group B was treated with S. boulardii in addition to BQT. The distribution of intestinal flora, serum interleukin-8 (IL-8), IL-17, tumor necrosis factor-α (TNF-α) levels, recovery time of clinical symptoms, total effective rate of clinical symptoms, H. pylori eradication rate, and adverse reactions were observed. Results: 2 weeks after treatment, the contents of Bifidobacterium, Bacteroides, and Lactobacillus in the intestinal tract of Group A decreased, while the amounts of Enterococcus and Enterobacter increased. In Group B, the contents of Bifidobacterium, Bacteroides, and Lactobacillus increased, while the amounts of Enterococcus and Enterobacter did not change significantly. Moreover, the trend of this flora change was still present at 4 weeks after treatment. Compared with Group A, Group B had lower IL-8, IL-17, and TNF-α levels, shorter recovery time of clinical symptoms, higher overall efficiency of clinical symptoms, and lower occurrence of adverse reactions. The eradication rate did not differ significantly between the two groups. Conclusion: BQT can lead to intestinal flora disorders in cagA+/vacA s1m1 H. pylori patients. S. boulardii can improve the distribution of intestinal flora, downregulate immune-inflammatory mediators, and modify clinical symptoms in patients.

Clinical Effect of Clarithromycin Combined with Tinidazole on Helicobacter pylori-Related Gastritis and Its Influence on COX-2 Expression.

Studies have shown that COX-2 expression is upregulated in gastric cancer (GC) as well as in precancerous lesions and in Helicobacter pylori-induced inflammation, suggesting that cyclooxygenase-2 (COX-2) may play an important role in gastric carcinogenesis. We attempted to investigate the role of clarithromycin with tinidazole on Helicobacter pylori-related gastritis from the aspects of clinical effect and COX-2 expression. From January 2016 to January 2019, 130 patients with Helicobacter pylori-related chronic gastritis were collected and grouped into the observation group (OG) and the control group (CG). Altogether, 80 patients in the OG were treated with clarithromycin with tinidazole, while 50 patients in the CG were treated with amoxicillin with metronidazole. Clinical symptom improvement time, content of COX-2 and B cell lymphoma-2 (BCL-2), content of inflammatory factors interleukin-1 (IL-1), IL-4, and C-reactive protein (CRP), expression level of nutritional indicators serum albumin (ALB), realbumin (PA), and transferrin (TF), clearance of Helicobacter pylori, total effective rate, and incidence of adverse reactions were detected. Compared with the CG, the OG had shorter clinical symptom improvement time, lower COX-2 and Bcl-2, lower expression of inflammatory factors IL-1, IL-4, and CRP, higher expression of nutritional indicators ALB, TF, and PA, higher clearance rate of Helicobacter pylori, higher total effective rate, and lower incidence of adverse reactions. Clarithromycin combined with tinidazole can effectively improve the clinical effect of Helicobacter pylori-related gastritis and reduce the expression level of COX-2.

302 W single-mode power from an Er/Yb fiber MOPA: publisher's note.

This publisher's note contains corrections to Opt. Lett.45, 2910 (2020).OPLEDP0146-959210.1364/OL.392786.

302 W single-mode power from an Er/Yb fiber MOPA.

There has been very little progress in the power scaling of Er/Yb fiber lasers in over a decade, reflecting the difficulties involved. Here we report, to the best of our knowledge, a new record of 302 W single-mode power from an Er/Yb fiber master oscillator power amplifier (MOPA) with a record optical efficiency of 56%, near the quantum limit. This is made possible by new fiber development from Nufern and off-resonant pumping of the Er/Yb fiber. We also show that further power scaling is no longer limited by ytterbium parasitic lasing but by fiber fuse in the Er/Yb fiber.

Predictive factors for lymph node metastasis and defining a subgroup treatable for laparoscopic lymph node dissection after endoscopic submucosal dissection in poorly differentiated early gastric cancer.

AIM: To investigate the predictive factors of lymph node metastasis (LNM) in poorly differentiated early gastric cancer (EGC); to guide the individual application of a combination of endoscopic submucosal dissection (ESD) and laparoscopic lymph node dissection (LLND) in a suitable subgroup of patients with poorly differentiated EGC. METHODS: We retrospectively analyzed 138 patients with poorly differentiated EGC who underwent gastrectomy with lymphadenectomy between January 1990 and December 2015. The association between the clinicopathological factors and the presence of LNM was retrospectively analyzed by univariate and multivariate logistic regression analyses. Odds ratios (OR) with 95% confidence interval (95%CI) were calculated. We further examined the relationship between the positive number of the significant predictive factors and the LNM rate. RESULTS: The tumor diameter (OR = 13.438, 95%CI: 1.773-25.673, P = 0.029), lymphatic vessel involvement (LVI) (OR = 38.521, 95%CI: 1.975-68.212, P = 0.015) and depth of invasion (OR = 14.981, 95%CI: 1.617-52.844, P = 0.024) were found to be independent risk factors for LNM by multivariate analysis. For the 138 patients diagnosed with poorly differentiated EGC, 21 (15.2%) had LNM. For patients with one, two and three of the risk factors, the LNM rates were 7.7%, 47.6% and 64.3%, respectively. LNM was not found in 77 patients that did not have one or more of the three risk factors. CONCLUSION: ESD might be sufficient treatment for intramucosal poorly differentiated EGC if the tumor is less than or equal to 2 cm in size and when LVI is absent upon postoperative histological examination. ESD with LLND may lead to the elimination of unnecessary gastrectomy in poorly differentiated EGC.

Efficient 240W single-mode 1018nm laser from an Ytterbium-doped 50/400µm all-solid photonic bandgap fiber.

Lowering the quantum defect by tandem pumping with fiber lasers at 1018nm was critical for achieving the record 10kW single-mode ytterbium fiber laser. Here we report the demonstration of an efficient directly-diode-pumped single-mode ytterbium fiber laser with 240W at 1018nm. The key for the combination of high efficiency, high power and single-mode at 1018nm is an ytterbium-doped 50µm/400µm all-solid photonic bandgap fiber, which has a practical all-solid design and a pump cladding much larger than those used in previous demonstrations of single-mode 1018nm ytterbium fiber lasers, enabling higher pump powers. Efficient high-power single-mode 1018nm fiber laser is critical for further power scaling of fiber lasers and the all-solid photonic bandgap fiber can potentially be a significant enabling technology.

Large-mode-area fibers operating near single-mode regime.

Lower NA in large-mode-area fibers enables better single-mode operation and larger core diameters. Fiber NA has traditionally been limited to 0.06, mostly due to the control tolerance in the fabrication process. It has been recognized recently that transverse mode instability is a major limit to average power scaling in fiber lasers. One effective method to mitigate this limit is to operate nearer to the single-mode regime. Lower fiber NA is critical in this since it allows relatively larger core diameters which is the key to mitigate the limits imposed by nonlinear effects. We have developed a fabrication process of ytterbium-doped silica glass which is capable of highly accurate refractive index control and sufficient uniformity for LMA fibers. This process is also capable of large-volume production. It is based on a significant amount of post-processing once the fiber preforms are made. We have demonstrated 30/400 and 40/400 LMA fibers with a NA of ~0.028 operating very close to the single-mode regime. The second-order mode cuts off at ~1.2µm and ~1.55µm respectively. We have also studied issues related to bend losses due to the low NA and further optimization of LMA fibers.

400-W near diffraction-limited single-frequency all-solid photonic bandgap fiber amplifier.

An ytterbium-doped large-mode area photonic bandgap fiber is used to demonstrate 400 W of single-frequency output at 1064 nm with excellent beam quality and minimal stimulated Brillouin scattering. The fiber possesses all-solid microstructures embedded in the cladding and a core composed of phosphosilicate with a diameter of ∼50 µm. As the signal power is pushed beyond 450 W, there is degradation in the beam quality due to the modal instability. We briefly discuss techniques to alleviate this problem in future designs. To the best of our knowledge, the 400-W single-frequency near diffraction-limited output far exceeds the current state-of-the-art from such type of fiber amplifier.

Highly efficient ytterbium-doped phosphosilicate fiber lasers operating below 1020 nm.

Highly-efficient high-power fiber lasers operating at wavelength below 1020 nm are critical for tandem-pumping in >10 kW fiber lasers to provide high pump brightness and low thermal loading. Using an ytterbium-doped-phosphosilicate double-clad leakage-channel fiber with ~50 µm core and ~420 µm cladding, we have achieved ~70% optical-to-optical efficiency at 1018 nm. The much larger cladding than those in previous reports demonstrates the much lower required pump brightness, a key for efficient kW operation. The demonstrated 1018 nm fiber laser has ASE suppression of ~41 dB. This is higher than previous reports and further demonstrates the advantages of the fiber used. Limiting factors to efficiency are also systematically studied.

Extending mode areas of single-mode all-solid photonic bandgap fibers.

Mode area scaling of optical fiber is highly desirable for high power fiber laser applications. It is well known that incorporation of additional smaller cores in the cladding can be used to resonantly out-couple higher-order modes from a main core to suppress higher-order-mode propagation in the main core. Using a novel design with multiple coupled smaller cores in the cladding, we have successfully demonstrated a single-mode photonic bandgap fiber with record effective mode area of ~2650µm(2). Detailed numeric studies have been conducted for multiple cladding designs. For the optimal designs, the simulated minimum higher-order-mode losses are well over two orders of magnitudes higher than that of fundamental mode when expressed in dBs. To our knowledge, this is the best higher-order-mode suppression ever found in fibers with this large effective mode areas. We have also experimentally validated one of the designs. M(2)<1.08 across the transmission band was demonstrated.

Polarizing ytterbium-doped all-solid photonic bandgap fiber with ~1150µm(2) effective mode area.

We demonstrate an Yb-doped polarizing all-solid photonic bandgap fiber for single-polarization and single-mode operation with an effective mode area of ~1150µm(2), a record for all-solid photonic bandgap fibers. The differential polarization mode loss is measured to be >5dB/m over the entire transmission band with a 160nm bandwidth and >15dB/m on the short wavelength edge of the band. A 2.6m long fiber was tested in a laser configuration producing a linearly polarized laser output with a PER value of 21dB without any polarizer, the highest for any fiber lasers based on polarizing fibers.