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Induction of ferroptosis, a recently defined form of nonapoptotic cell death caused by iron-dependent lipid peroxidation, has emerged as an anticancer strategy. Erastin is a ferroptosis activator that promotes cell death that not only depends on the depletion of cellular cysteine but also relies on mitochondrial oxidative metabolism of glutamine. Here, we demonstrate that ASS1, a key enzyme involved in the urea cycle, plays a crucial role in ferroptosis resistance. Loss of ASS1 increased the sensitivity of non–small cell lung cancer (NSCLC) cells to erastin in vitro and decreased tumor growth in vivo. Metabolomics analysis with stable isotope-labeled glutamine showed that ASS1 promotes reductive carboxylation of cytosolic glutamine and compromises the oxidative tricarboxylic acid cycle from glutamine anaplerosis, reducing mitochondrial-derived lipid reactive oxygen species. Moreover, transcriptome sequencing showed that ASS1 activates the mTORC1–SREBP1–SCD5 axis to promote de novo monounsaturated fatty acid synthesis by using acetyl-CoA derived from the glutamine reductive pathway. Treating ASS1-deficient NSCLC cells with erastin combined with arginine deprivation significantly enhanced cell death compared with either treatment alone. Collectively, these results reveal a previously unknown regulatory role of ASS1 in ferroptosis resistance and provide a potential therapeutic target for ASS1-deficient NSCLC. Significance: ASS1 promotes reductive carboxylation of glutamine and confers ferroptosis resistance, providing multiple treatment options for ASS1-deficient non–small cell lung cancer.

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Supplementary Table 1 Primer sequences

Induction of ferroptosis, a recently defined form of nonapoptotic cell death caused by iron-dependent lipid peroxidation, has emerged as an anticancer strategy. Erastin is a ferroptosis activator that promotes cell death that not only depends on the depletion of cellular cysteine but also relies on mitochondrial oxidative metabolism of glutamine. Here, we demonstrate that ASS1, a key enzyme involved in the urea cycle, plays a crucial role in ferroptosis resistance. Loss of ASS1 increased the sensitivity of non–small cell lung cancer (NSCLC) cells to erastin in vitro and decreased tumor growth in vivo. Metabolomics analysis with stable isotope-labeled glutamine showed that ASS1 promotes reductive carboxylation of cytosolic glutamine and compromises the oxidative tricarboxylic acid cycle from glutamine anaplerosis, reducing mitochondrial-derived lipid reactive oxygen species. Moreover, transcriptome sequencing showed that ASS1 activates the mTORC1–SREBP1–SCD5 axis to promote de novo monounsaturated fatty acid synthesis by using acetyl-CoA derived from the glutamine reductive pathway. Treating ASS1-deficient NSCLC cells with erastin combined with arginine deprivation significantly enhanced cell death compared with either treatment alone. Collectively, these results reveal a previously unknown regulatory role of ASS1 in ferroptosis resistance and provide a potential therapeutic target for ASS1-deficient NSCLC.Significance:ASS1 promotes reductive carboxylation of glutamine and confers ferroptosis resistance, providing multiple treatment options for ASS1-deficient non–small cell lung cancer.

Tumor spread through air space (STAS) is a novel pattern of invasion related to poor prognosis in non-small cell cancer (NSCLC). Nevertheless, little is known about the role of STAS in small cell lung cancer (SCLC). We sought to determine whether STAS has a significant effect on recurrence among SCLC patients.We collected clinical and follow-up information from 181 resected stage I-III SCLC patients and compared overall survival (OS) and disease-free survival (DFS) between the patients with or without STAS using the Kaplan‒Meier method. To explore the effect of STAS on recurrence, a competing-risk analysis was conducted.Among 181 SCLC patients, STAS was observed in 56 (30.94%) patients, and 125 (69.06%) patients did not have STAS. Furthermore, 33 (18.23%) patients had recurrence, including 12 patients with brain metastases. Patients with STAS had worse DFS. The cumulative incidence of any recurrence was higher in patients with STAS than in those without STAS. Univariate and multivariate competing-risk regression analyses revealed that sublobar resection and STAS were independent risk factors for SCLC recurrence (p = 0.009 and p = 0.029 for multivariate analysis, respectively).SCLC patients with STAS have worse DFS than SCLC patients without STAS. STAS is an independent prognostic factor in SCLC patients.

This study aims to investigate the effect of lymph node examination on overall survival (OS) and lung cancer-specific survival (LCSS) in stage I second primary lung cancer (SPLC) patients who underwent second pulmonary resection. We conducted a retrospective study with the Surveillance, Epidemiology, and End Results (SEER) database to identify stage I SPLC patients who received surgery from 1998 to 2015. The Kaplan–Meier method with landmark analysis and multivariable Cox regression analysis were performed to evaluate the prognostic value of lymph node examination. A total of 842 patients from the SEER database with stage I SPLC who underwent a second surgical treatment were included. The 5-year survival rate was 54.8% for the whole cohort. Multivariable analysis revealed that the number of lymph nodes examined (LNE) was associated with better OS and LCSS in SPLC patients after 12 months postoperatively. Patients with contralateral SPLC had significantly more nodes removed than those with ipsilateral SPLC. For contralateral SPLC, more than 10 LNE was correlated with improved long-term survival outcomes. Ipsilateral SPLC patients benefited from 4 or more LNE. However, the current analysis did not show a significant survival benefit from lymph node examination within 12 months after surgery. For stage I SPLC patients who received surgical treatment after initial resection, an adequate number of LNE would improve both OS and LCSS. We recommend more than 10 LNE for contralateral SPLC and at least 4 LNE for ipsilateral SPLC.

[This corrects the article DOI: 10.1371/journal.ppat.1009401.].

Immunotherapy has revolutionized cancer treatment, but most patients are refractory to immunotherapy or acquire resistance. To explore immunotherapy resistance mechanisms, we characterized the transcriptomes of ~92000 single cells from 15 patients with non-small cell lung cancer (NSCLC) during neoadjuvant PD-1 blockade combined with chemotherapy. CD8+ T, natural killer, B, and dendritic cells were activated by therapy. Therapy also promoted differentiation of memory T cells into effector T cells. Macrophages were remodeled into an M0-like phenotype and neutrophils into an aged phenotype. Distinct therapy-induced cancer-cell transcriptomes were associated with clinical response. Major pathologic responders (MPRs) activated antigen presentation via major histocompatibility complex class II (MHC-II). Cancer cells of non-MPRs exhibited overexpression of estrogen metabolism enzymes and elevated serum estradiol. Elevated estradiol activated EGFR signaling and upregulated the expression of VEGFA, which promoted an immunosuppressive microenvironment. FCRL4+FCRL5+ memory B cells and CD16+CX3CR1+ monocytes were identified as biomarkers for positive immunotherapy response.

Knowledge of the tumor microenvironment (TME) in patients with early lung cancer, especially in comparison with the matched adjacent tissues, remains lacking. To characterize TME of early-stage lung adenocarcinoma, we performed RNA-seq profiling on 58 pairs of minimally invasive adenocarcinoma (MIA) tumors and matched adjacent normal tissues. MIA tumors exhibited an adaptive TME characterized by high CD4

Cyclic GMP-AMP synthase (cGAS), serving as a primary sensor of intracellular DNA, is essential to initiate anti-microbial innate immunity. Inappropriate activation of cGAS by self-DNA promotes severe autoinflammatory diseases such as Aicardi–Goutières syndrome (AGS); thus, inhibition of cGAS may provide therapeutic benefit in anti-autoimmunity. Here we report that perillaldehyde (PAH), a natural monoterpenoid compound derived from Perilla frutescens, suppresses cytosolic-DNA-induced innate immune responses by inhibiting cGAS activity. Mice treated with PAH are more susceptible to herpes simplex virus type 1 (HSV-1) infection. Moreover, administration with PAH markedly ameliorates self-DNA-induced autoinflammatory responses in a mouse model of AGS. Collectively, our study reveals that PAH can effectively inhibit cGAS-STING signaling and could be developed toward the treatment of cGAS-mediated autoimmune diseases.

ObjectiveThe choice of adjuvant therapy for early stage lung adenocarcinoma (LUAD) remains controversial. Identifying the metabolism characteristics leading to worse prognosis may have clinical utility in offering adjuvant therapy.MethodsThe gene expression profiles of LUAD were collected from 22 public datasets. The patients were divided into a meta-training cohort (n = 790), meta-testing cohort (n = 716), and three independent validation cohorts (n = 345, 358, and 321). A metabolism-related gene pair index (MRGPI) was trained and validated in the cohorts. Subgroup analyses regarding tumor stage and adjuvant chemotherapy (ACT) were performed. To explore potential therapeutic targets, we performed in silico analysis of the MRGPI.ResultsThrough machine learning, MRGPI consisting of 12 metabolism-related gene pairs was constructed. MRGPI robustly stratified patients into high- vs low-risk groups in terms of overall survival across and within subpopulations with stage I or II disease in all cohorts. Multivariable analysis confirmed that MRGPI was an independent prognostic factor. ACT could not improve prognosis in high-risk patients with stage I disease, but could improve prognosis in the high-risk patients with stage II disease. In silico analysis indicated that B3GNT3 (overexpressed in high-risk patients) and HSD17B6 (down-expressed in high-risk patients) may make synergic reaction in immune evasion by the PD-1/PD-L1 pathway. When integrated with clinical characteristics, the composite clinical and metabolism signature showed improved prognostic accuracy.ConclusionsMRGPI could effectively predict prognosis of the patients with early stage LUAD. The patients at high risk may get survival benefit from PD-1/PD-L1 blockade (stage I) or combined with chemotherapy (stage II).

The cytosolic DNA sensor cyclic GMP-AMP (cGAMP) synthetase (cGAS) has emerged as a fundamental component fueling the anti-pathogen immunity. Because of its pivotal role in initiating innate immune response, the activity of cGAS must be tightly fine-tuned to maintain immune homeostasis in antiviral response. Here, we reported that neddylation modification was indispensable for appropriate cGAS-STING signaling activation. Blocking neddylation pathway using neddylation inhibitor MLN4924 substantially impaired the induction of type I interferon and proinflammatory cytokines, which was selectively dependent on Nedd8 E2 enzyme Ube2m. We further found that deficiency of the Nedd8 E3 ligase Rnf111 greatly attenuated DNA-triggered cGAS activation while not affecting cGAMP induced activation of STING, demonstrating that Rnf111 was the Nedd8 E3 ligase of cGAS. By performing mass spectrometry, we identified Lys231 and Lys421 as essential neddylation sites in human cGAS. Mechanistically, Rnf111 interacted with and polyneddylated cGAS, which in turn promoted its dimerization and enhanced the DNA-binding ability, leading to proper cGAS-STING pathway activation. In the same line, the Ube2m or Rnf111 deficiency mice exhibited severe defects in innate immune response and were susceptible to HSV-1 infection. Collectively, our study uncovered a vital role of the Ube2m-Rnf111 neddylation axis in promoting the activity of the cGAS-STING pathway and highlighted the importance of neddylation modification in antiviral defense., Author summary The Cyclic GMP-AMP (cGAMP) synthase (cGAS) is a critical cytosolic DNA sensor by monitoring pathogens-derived DNA, while its aberrant activation leads to tissue damage. Thus, the activity of cGAS must be tightly regulated to keep immune homeostasis. Several post-translational modifications have been demonstrated to be important in fine-tuning activities of cGAS. However, the mechanism underlying how cGAS is precisely regulated remains not fully understood. In this study, we uncovered that cGAS was poly-neddylated by the Ube2m-Rnf111 axis, and the poly-NEDD8 chains played a role as nexus in linking the second cGAS, leading to the appropriate dimerization and the subsequent activation of cGAS. Our study revealed a novel and critical role of neddylation in the regulation of the cGAS-STING signaling pathway and provided a new perspective for restricting the infection of DNA pathogens.

Lung adenocarcinoma is the leading cause of cancer death. However, knowledge of the tumor immune microenvironment in early lung cancer patients, especially in comparison with the matched adjacent tissues, remains lacking. To characterize the tumor microenvironment (TME) of early-stage lung adenocarcinoma, we performed RNA-seq profiling on 58 pairs of minimally invasive adenocarcinoma (MIA) tumors and matched adjacent normal lung tissues. We observed over-expression and glycosylation of mucins, along with altered cytokine-cytokine interactions in MIA tumors. MIA tumors also exhibited an adaptive immune TME characterized by high CD4+ T-cell infiltration, high plasma B-cell activation, and low CD8+ T-cell infiltration. The high expression of markers for B cells, activated CD4+ T cells, and follicular helper T (Tfh) cells in bulk MIA samples and three independent single-cell RNA-seq datasets implied the formation of tertiary lymphoid structures (TLS). Multiplex immunohistochemistry (mIHC) staining of 22 MIA tumors validated TLS formation and revealed an enrichment of follicular regulatory T cells (Tfr) in TLS follicles, which may explain the lower CD8+ T-cell infiltration and attenuated anti-tumor immunity in MIA. Our study demonstrates how integrating tumor transcriptome analysis and pathology can characterize the TME and elucidate potential mechanisms of tumor immune evasion.

Background Combined small cell lung cancer (CSCLC) is an uncommon and heterogeneous subtype of small cell lung cancer (SCLC). However, there is limited data concerning the different molecular changes and clinical features in CSCLC compared to pure SCLC. Methods The clinical and pathological characteristics of pure SCLC and CSCLC patients were analyzed. Immunohistochemistry and microdissection were performed to isolate the CSCLC components. Further molecular analysis was carried out by next-generation sequencing (NGS) in 12 CSCLC and 30 pure SCLC. Results There were no significant differences in clinical features between CSCLC and pure SCLC. Overall survival (OS) of CSCLC patients was worse than pure SCLC (P=0.005). NGS results indicated that TP53 and RB1 were the most frequently mutated genes in both CSCLC (83.33% and 66.67%) and pure SCLC (80.00% and 63.33%) groups. However, less than 10% common mutations were found in both CSCLC and pure SCLC. When analyzing the data of SCLC and non-small cell lung cancer (NSCLC) components of CSCLC, more than 50% common mutations, and identical genes with mutations were detected. Moreover, there were also common biological processes and signaling pathways identified in CSCLC and pure SCLC, in addition to SCLC and NSCLC components. Conclusions There were no significant differences in terms of clinical features between CSCLC and pure SCLC. However, the prognosis for CSCLC was worse than pure SCLC. NGS analysis suggested that CSCLC components might derive from the same pluripotent single clone with common initial molecular alterations and subsequent acquisitions of other genetic mutations.

Lung adenocarcinoma is the leading cause of cancer death. To characterize the tumor microenvironment (TME) of early-stage lung adenocarcinoma, we performed RNA-seq profiling on 59 pairs of minimally invasive adenocarcinoma (MIA) tumors and matched adjacent normal lung tissues from Chinese patients. We observed mucin over-expression and glycosylation, and altered cytokine-cytokine interactions in MIA tumors, which also had distinct adaptive immune TME of higher CD4+ T cell infiltration, higher plasma B cell activation, and lower CD8+ T cell infiltration. The high expression of markers for B cells, activated CD4 T cells, and follicular helper T (Tfh) cells in MIA implicated the formation of tertiary lymphoid structures (TLS), which were supported by two independent single-cell RNA-seq data. Multiplex immunohistochemistry (mIHC) staining of 22 MIA tumors validated TLS formation and revealed an enrichment of follicular regulatory T cells (Tfr) in TLS follicles, which may explain the lower CD8+ T cell infiltration and attenuated anti-tumor immunity in MIA.SignificanceWe discovered a potential immunosuppressive phenotype in MIA mediated by follicular regulatory T cells (Tfr) in TLS formation, which could be a potential mechanism of CD8+ T cell exclusion. Our study demonstrated how integrating tumor transcriptome and pathology can characterize the TME and elucidate potential mechanisms of tumor immune evasion.

Background Malignant transformation and progression of cancer are driven by the co-evolution of cancer cells and their dysregulated tumor microenvironment (TME). Recent studies on immunotherapy demonstrate the efficacy in reverting the anti-tumoral function of T cells, highlighting the therapeutic potential in targeting certain cell types in TME. However, the functions of other immune cell types remain largely unexplored. Results We conduct a single-cell RNA-seq analysis of cells isolated from tumor tissue samples of non-small cell lung cancer (NSCLC) patients, and identify subtypes of tumor-infiltrated B cells and their diverse functions in the progression of NSCLC. Flow cytometry and immunohistochemistry experiments on two independent cohorts confirm the co-existence of the two major subtypes of B cells, namely the naïve-like and plasma-like B cells. The naïve-like B cells are decreased in advanced NSCLC, and their lower level is associated with poor prognosis. Co-culture of isolated naïve-like B cells from NSCLC patients with two lung cancer cell lines demonstrate that the naïve-like B cells suppress the growth of lung cancer cells by secreting four factors negatively regulating the cell growth. We also demonstrate that the plasma-like B cells inhibit cancer cell growth in the early stage of NSCLC, but promote cell growth in the advanced stage of NSCLC. The roles of the plasma-like B cell produced immunoglobulins, and their interacting proteins in the progression of NSCLC are further validated by proteomics data. Conclusion Our analysis reveals versatile functions of tumor-infiltrating B cells and their potential clinical implications in NSCLC.

Additional file 5. Review history.

Additional file 1: Figure S1. Representative illustration of gene expression in single cell RNA-seq. Figure S2. Identification of cell-cell interactions between different cells in the microenvironment of NSCLC. Figure S3. CD20+ B cells inhibit the cell growth and invasion in H1299 cells. Figure S4. Plasma-like B cells exert a different effect on tumor cells in different stages of lung cancer. Figure S5. Representative illustration of TRIM21, FCGR3A, C1QA, C1QB, C1QC, AP2A1, AP2M1, AP2A2, RHOC, CTTND1 and CTNNB1 expression.

Objective(s) Lymph node status is vital for patients with small cell lung cancer (SCLC). We sought to evaluate the association between the number of lymph nodes examined (NLNE) and prognosis and nodal upstaging in stage I SCLC patients. Methods We queried the Surveillance, Epidemiology and End Results (SEER) database and our department for surgically treated patients with pathologic stage I SCLC to evaluate the correlation between NLNE and overall survival (OS). We further investigated the association between the NLNE and nodal upstaging in clinical stage I SCLC. Results A total of 878 patients with pathologic stage I SCLC were enrolled from the SEER database. Univariate and multivariate Cox regression analysis revealed that removing more than 6 lymph nodes was associated with significantly improved OS. We validated the prognostic impact from examining more than 6 nodes in pathologic stage I SCLC patients from our department. Logistic regression analysis found that removing more than 6 nodes increased the odds of nodal upstaging for clinical stage I SCLC. Conclusions Adequate nodal examination leads to survival benefits and accurate nodal staging. Our analysis indicated that examining more than 6 lymph nodes could confer better OS and predict nodal upstaging for stage I SCLC patients.

Dengue viruses (DENVs) are an emerging threat to global public health. The NS2B3 protease complex of DENV has recently been shown to cleave the antiviral protein STING and thereby subvert the innate immune signaling to facilitate virus replication. Whether host cells have a mechanism to counteract this virus-mediated immunosuppression is unclear. We discovered that the K27-linked polyubiquitination of NS3 protein facilitates its recruitment of NS2B, the formation of NS2B3, and consequently the enhanced cleavage of STING. However, an endoplasmic reticulum (ER) protein, SCAP, through binding to NS2B protein, inhibits the ubiquitination of NS3, rendering NS2B3 protease incapable of binding and cleaving STING. Importantly, ectopic expression of SCAP impaired DENV infection, whereas silencing of SCAP potentiated DENV infection. Collectively, this study uncovered a novel function of SCAP of counteracting the inhibitory action of DENV NS2B3 protease on STING signaling, suggesting that modulation of SCAP levels may have therapeutic implications.

Dengue viruses (DENVs) are an emerging threat to global public health. The NS2B3 protease complex of DENV has recently been shown to cleave the antiviral protein STING and thereby subvert the innate immune signaling to facilitate virus replication. Whether host cells have a mechanism to counteract this virus-mediated immunosuppression is unclear. We discovered that the K27-linked polyubiquitination of NS3 protein facilitates its recruitment of NS2B, the formation of NS2B3, and consequently the enhanced cleavage of STING. However, an endoplasmic reticulum (ER) protein, SCAP, through binding to NS2B protein, inhibits the ubiquitination of NS3, rendering NS2B3 protease incapable of binding and cleaving STING. Importantly, ectopic expression of SCAP impaired DENV infection, whereas silencing of SCAP potentiated DENV infection. Collectively, this study uncovered a novel function of SCAP of counteracting the inhibitory action of DENV NS2B3 protease on STING signaling, suggesting that modulation of SCAP levels may have therapeutic implications. IMPORTANCE This study reports the first ubiquitylation target protein in DENV, the NS3 protein, and the unique role of K27-linked polyubiquitylation in NS3's ability to recruit NS2B and formation of the NS2B3 protease complex. Additionally, this study identified novel functions of the ER protein SCAP: one is to compete with NS2B for binding to STING, and the other is to inhibit the ubiquitination of NS3. Both of these functions protect STING from being cleaved by the NS2B3 protease and thus contribute to host antiviral response.

Summary: cGAS-STING signaling is essential for innate immunity. Its misregulation promotes cancer or autoimmune and autoinflammatory diseases, and it is imperative to identify effective lead compounds that specifically downregulate the pathway. We report here that astin C, a cyclopeptide isolated from the medicinal plant Aster tataricus, inhibits cGAS-STING signaling and the innate inflammatory responses triggered by cytosolic DNAs. Moreover, mice treated with astin C are more susceptible to HSV-1 infection. Consistently, astin C markedly attenuates the autoinflammatory responses in Trex1−/− BMDM cells and in Trex1−/− mouse autoimmune disease model. Mechanistically, astin C specifically blocks the recruitment of IRF3 onto the STING signalosome. Collectively, this study characterizes a STING-specific small-molecular inhibitor that may be applied for potentially manipulating the STING-mediated clinical diseases. : Li et al. have characterized a small-molecule cyclopeptide, astin C, which specifically inhibits cGAS-STING signaling as well as the innate inflammatory responses. This finding provides a way to potentially manipulate STING-mediated clinical diseases. Keywords: cGAS, STING, IRF3, TBK1, HSV-1, cyclopeptide, astin C, therapeutic target, innate immunity, autoimmune diseases

Stimulator of interferon genes (STING, also known as MITA, ERIS or MPYS) induces the activation of TBK1 kinase and IRF3 transcription factor, upon sensing of microbial DNAs. How IRF3 is recruited onto the STING signalosome remains unknown. We report here that silencing of the ER adaptor SCAP markedly impairs the IRF3-responsive gene expression induced by STING. Scap knockdown mice are more susceptible to HSV-1 infection. Interestingly, SCAP translocates from ER, via Golgi, to perinuclear microsome in a STING-dependent manner. Mechanistically, the N-terminal transmembrane domain of SCAP interacts with STING, and the C-terminal cytosolic domain of SCAP binds to IRF3, thus recruiting IRF3 onto STING signalosome. Mis-localization of SCAP abolishes its antiviral function. Collectively, this study characterizes SCAP as an essential adaptor in the STING signaling pathway, uncovering a critical missing link in DNAs-triggered host antiviral responses., Author Summary The stimulator of interferon genes (STING/MITA/ERIS/MPYS) is characterized as the converging point of the cytosolic DNAs-triggered innate immune signaling, and its function has been well documented in mediating the production of type I interferon and other pro-inflammatory cytokines. It remains intriguing to address how IRF3 is recruited onto the STING signalosome. In this study, we have further identified and characterized the SREBP cleavage-activating protein (SCAP) as the long-sought-after adaptor of the STING signaling. Upon microbial DNA challenge, SCAP translocates from ER, via Golgi, to perinuclear microsome in a STING-dependent manner. SCAP thus serves as a scaffold adaptor to recruit IRF3 and facilitate its integration into the perinuclear microsomes. Our study reveals an important missing link in innate immunity, further highlighting the physical and/or functional links between innate immunity and metabolism.

In this letter we report a simple single-stage amplifier realized as high as 62 W average power output at 1064 nm wavelength, 40 picoseconds pulse width and 80 MHz repetition from 0.7 W seed laser based on backward pumped master-oscillator fiber power amplifier (MOPA) system. It is can stable operation in 57.6 W output for hours. We applied a semiconductor saturable absorber mirror (SESAM) passive mode-lock Nd:YVO4 oscillator as seed source and 6m long 20 μm core double-cladding Yb-doped fiber (YDF) as gain medium. To the best of our knowledge, 62 W average power is the highest output of single-stage ps-pulse amplifier with 20 μm-core fiber. None amplified spontaneous emission (ASE) and stimulated Raman scattering (SRS) nonlinear phenomenon was observed in 57.6 W high average power output.

We report on a passively mode-locked Nd:YVO4 laser using a novel graphene oxide saturable absorber fabricated by vertical evaporation method. An 880 nm LD pump source was used to reduce the thermal load of the laser crystal. At the pump power of 7.4 W, 1.2 W average output power of continuous wave mode-locked laser with optical conversion efficiency of 16.2% was achieved. To the best of our knowledge, this is the highest output power of passively mode-locked solid-state laser using graphene oxide saturable absorber. The repetition rate of passively mode-locked pulse was 88 MHz with the pulse energy of 13.6 nJ.

We report on an 880 nm LD pumped passive mode-locked TEM00 Nd:YVO4 laser based on a semiconductor saturable absorber mirror (SESAM), with a high optical-to-optical conversion efficiency of 67.3%, and a slope efficiency of 71%. When the absorbed pump power was 11 W, 7.4 W average output power of 1064 nm continuous-wave mode-locked laser was achieved. To our knowledge, this is the highest optical-to-optical conversion efficiency among all the published reports of 880 nm LD pumped SESAM passive mode-locked lasers. The repetition rate of mode-locked pulse was 80 MHz with 26 ps pulse width. The maximum pulse energy and peak power were 92.5 nJ and 3.6 kW, respectively.

We reported on a master-oscillator fiber power amplifier (MOPA) system and a second-harmonic generation (SHG) system. Actively Q-switched Nd:YVO(4) laser was used as a seed source of light pluses. The MOPA system produced as much as 76 kW of peak power at wavelength of 1064 nm, with 35 kHz repetition rate and 20 ns pulse duration. With a lithium triborate (LBO) crystal at type II phase matching, a maximum 16 kW of peak power had been demonstrated. The fiber nonlinear effects such as stimulate Brillouin scattering (SBS) and stimulate Raman scattering (SRS) and the SHG conversion efficiency were investigated.

We report a passive mode-locked Nd:YVO4 laser pumped by 880 nm LD using a transmission-type multi-walled carbon nanotube saturable absorber. At the pump power of 6.1 W, the average output power of 0.8 W of continuous wave mode-locked laser with optical conversion efficiency of 13.1% was generated. The repetition rate and pulse energy of the mode-locked pulse were 88 MHz and 9.1 nJ, respectively.

A ytterbium-doped double-clad fiber laser generating up to 1026 W of continuous-wave output power at 1085 nm with a slope efficiency of 74% by single-ended backward pumping configuration is reported. The core diameter was 20 μm with a low numerical aperture of 0.06, and a good beam quality (BPP < 1.8 mm mrad) is achieved without special mode selection methods. No undesirable roll-over was observed in output power with increasing pump power, and the maximum output power was limited by the available pump power. The instability of maximum output power was better than ±0.6%. Different pumping configurations were also compared in experiment, which shows good agreements with theoretical analyses.