Realization of a compact 10-W 976-nm ytterbium-doped all-fiber laser.

We have demonstrated a compact and cost-effective ytterbium-doped all-fiber laser operating at 976 nm. By utilizing a commercially available ytterbium-doped fiber with a length of only 18 cm, we achieved a lasing power of 10.3 W, with a slope efficiency of 25.4%. To our knowledge, our work presents the shortest gain fiber ever documented in the literature capable of delivering tens-of-watt 976-nm lasing power. The design is compatible with conventional fiber components, simplifying the monolithic assembly process. Notably, the incorporation of such a short gain fiber obviated the need for additional measures to suppress the strong 1.03-µm emission.

Opioid-Modulated Receptor Localization and Erk1/2 Phosphorylation in Cells Coexpressing µ-Opioid and Nociceptin Receptors.

We attempted to examine the alterations elicited by opioids via coexpressed µ-opioid (MOP) and nociceptin/orphanin FQ (NOP) receptors for receptor localization and Erk1/2 (p44/42 MAPK) in human embryonic kidney (HEK) 293 cells. Through two-photon microscopy, the proximity of MOP and NOP receptors was verified by fluorescence resonance energy transfer (FRET), and morphine but not buprenorphine facilitated the process of MOP-NOP heterodimerization. Single-particle tracking (SPT) further revealed that morphine or buprenorphine hindered the movement of the MOP-NOP heterodimers. After exposure to morphine or buprenorphine, receptor localization on lipid rafts was detected by immunocytochemistry, and phosphorylation of Erk1/2 was determined by immunoblotting in HEK 293 cells expressing MOP, NOP, or MOP+NOP receptors. Colocalization of MOP and NOP on lipid rafts was enhanced by morphine but not buprenorphine. Morphine stimulated the phosphorylation of Erk1/2 with a similar potency in HEK 293 cells expressing MOP and MOP+NOP receptors, but buprenorphine appeared to activate Erk1/2 solely through NOP receptors. Our results suggest that opioids can fine-tune the cellular localization of opioid receptors and phosphorylation of Erk1/2 in MOP+NOP-expressing cells.

Streptococcus vulneris sp. nov., isolated from wound of patient with diabetic foot ulcer (DFU).

A new α-haemolytic streptococcal strain, designated DM3B3T, was isolated from the wound of a diabetic foot ulcer (DFU) patient. Phylogenetic analysis based on 16S rRNA full-gene sequencing (1563 bp) revealed highest sequence similarity to Streptococcus mitis (99.7%), followed by "Streptococcus gwangjuense" (99.6%), and Streptococcus pseudopneumoniae (99.5%). Comparison of five housekeeping genes, groEL, rpoB, sodA, recA and pheS, revealed that strain DM3B3T was well separated from the Streptococcus reference strains. The complete genome of strain DM3B3T consisted of 1,963,039 bp with a G + C content of 41.0 mol%. Average nucleotide identity values between strain DM3B3T and Streptococcus mitis NCTC 12261T, "Streptococcus gwangjuense" ChDC B345T, and Streptococcus pseudopneumoniae ATCC BAA-960T were 93.8%, 94.4%, and 92.2%, respectively. The highest digital DNA-DNA hybridization value with respect to the closest species was 57.5%, i.e., below the species cut-off of 70% hybridization. The main cellular fatty acids of strain DM3B3T were 16:0, 18:1ω7c, 18:1ω9c and 18:0. On the basis of phylogenetic, genotypic and phenotypic data, we propose to classify this isolate as representative of a novel species of the genus Streptococcus, Streptococcus vulneris sp. nov., in reference to its isolation from wound, with strain DM3B3T (= NBRC 114638T = BCRC 81288T) as the type strain.

Fructobacillus papyriferae sp. nov., Fructobacillus papyrifericola sp. nov., Fructobacillus broussonetiae sp. nov. and Fructobacillus parabroussonetiae sp. nov., isolated from paper mulberry in Taiwan.

Five Gram-stain-positive strains (M1-10T, M1-13, M1-21T, M2-14T and S1-1T) were isolated from paper mulberry (Broussonetia papyrifera) in Taiwan. Cells were rod-shaped, non-motile, non-haemolytic, asporogenous, facultatively anaerobic, heterofermentative, and did not exhibit catalase and oxidase activities. Phylogenetic analysis of the 16S rRNA gene sequences revealed that these novel strains belonged to the genus Fructobacillus. On the basis of 16S rRNA gene sequence similarities, the type strains of Fructobacillus fructosus and Fructobacillus durionis were the closest neighbours to strains M1-10T, M1-13, M1-21T, M2-14T and S1-1T. Sequence analyses of concatenated two partial housekeeping genes, the RNA polymerase beta subunit (rpoC) and recombinase A (recA) also indicated that the novel strains belonged to the genus Fructobacillus. The 16S rRNA and concatenated rpoC and recA gene sequence similarities between strains M1-10T and M1-13 were 100 %, respectively. The average nucleotide identity values of M1-10T, M1-21T, M2-14T and S1-1T with F. fructosus and F. durionis were 75.1-78.9% and 76.5-77.5 %, respectively. The digital DNA-DNA hybridization values were 19.7-21.5% and 19.6-20.4 %, respectively. Phenotypic and genotypic test results demonstrated that these strains represent four novel species of the genus Fructobacillus, for which the names Fructobacillus papyriferae sp. nov., Fructobacillus papyrifericola sp. nov., Fructobacillus broussonetiae sp. nov. and Fructobacillus parabroussonetiae sp. nov. are proposed with the type strains M1-10T (=BCRC 81237T=NBRC 114433T), M1-21T (=BCRC 81239T=NBRC 114435T), M2-14T (=BCRC 81240T=NBRC 114436T) and S1-1T (=BCRC 81241T=NBRC 114437T), respectively.

Fructobacillus apis sp. nov., isolated from the gut of honeybee (Apis mellifera).

A Gram-positive, facultatively anaerobic, catalase-negative, fructose-dependent strain (W13T) was isolated from the gut of honeybee (Apis mellifera). Phylogenetic analysis based on 16S rRNA gene sequencing indicated that strain W13T represents a distinct line of descent within the genus Fructobacillus, with the closest neighbours being Fructobacillus broussonetiae BCRC 81240T (98.9 % sequence similarity) and Fructobacillus durionis DSM 19113T (96.8 % sequence similarity). Comparative sequencing of the additional phylogenetic markers rpoC and recA confirmed the 16S rRNA gene tree topology. The complete genome of strain W13T consisted of 1 292 712 bp with a G+C content of 48.3 mol%. Pairwise comparisons of the average nucleotide identity values and digital DNA-DNA hybridization values between the genomes of W13T and its close phylogenetic neighbours, F. broussonetiae BCRC 81240T and F. durionis DSM 19113T, resulted in 76.2-84.1 % and 20.2-27.6 %, respectively. The main cellular fatty acids of strain W13T were C16 : 0, C18 : 1 ω9c and C18 : 1 ω7c. Thus, we propose a novel species within the genus Fructobacillus, with the name Fructobacillus apis sp. nov. and the type strain is W13T (= NBRC 115637T=BCRC 81365T).

Vibrio salinus sp. nov., a marine nitrogen-fixing bacterium isolated from the lagoon sediment of an islet inside an atoll in the western Pacific Ocean.

A marine, facultatively anaerobic, nitrogen-fixing bacterium, designated strain DNF-1T, was isolated from the lagoon sediment of Dongsha Island, Taiwan. Cells grown in broth cultures were Gram-negative rods that were motile by means of monotrichous flagella. Cells grown on plate medium produced prosthecae and vesicle-like structures. NaCl was required and optimal growth occurred at about 2-3% NaCl, 25-30 °C and pH 7-8. The strain grew aerobically and was capable of anaerobic growth by fermenting D-glucose or other carbohydrates as substrate. Both the aerobic and anaerobic growth could be achieved with NH4Cl as a sole nitrogen source. When N2 served as the sole nitrogen source only anaerobic growth was observed. Major cellular fatty acids were C14:0, C16:0 and C16:1 ω7c, while major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. The DNA G+C content was 42.2 mol% based on the genomic DNA data. Phylogenetic analyses based on 16S rRNA genes and the housekeeping genes, gapA, pyrH, recA and gyrB, revealed that the strain formed a distinct lineage at species level in the genus Vibrio of the family Vibrionaceae. These results and those from genomic, chemotaxonomic and physiological studies strongly support the assignment of a novel Vibrio species. The name Vibrio salinus sp. nov. is proposed for the novel species, with DNF-1T (= BCRC 81209T = JCM 33626T) as the type strain. This newly proposed species represents the second example of the genus Vibrio that has been demonstrated to be capable of anaerobic growth by fixing N2 as the sole nitrogen source.

BPR0C261, An Analogous of Microtubule Disrupting Agent D-24851 Enhances the Radiosensitivity of Human Non-Small Cell Lung Cancer Cells via p53-Dependent and p53-Independent Pathways.

(1) Destabilization of microtubule dynamics is a primary strategy to inhibit fast growing tumor cells. The low cytotoxic derivative of microtubule inhibitor D-24851, named BPR0C261 exhibits antitumor activity via oral administration. In this study, we investigated if BPR0C261 could modulate the radiation response of human non-small cell lung cancer (NSCLC) cells with or without p53 expression. (2) Different doses of BPR0C261 was used to treat human NSCLC A549 (p53+/+) cells and H1299 (p53-/-) cells. The cytotoxicity, radiosensitivity, cell cycle distribution, DNA damage, and protein expression were evaluated using an MTT assay, a colony formation assay, flow cytometry, a comet assay, and an immunoblotting analysis, respectively. (3) BPR0C261 showed a dose-dependent cytotoxicity on A549 cells and H1299 cells with IC50 at 0.38 µM and 0.86 µM, respectively. BPR0C261 also induced maximum G2/M phase arrest and apoptosis in both cell lines after 24 h of treatment with a dose-dependent manner. The colony formation analysis demonstrated that a combination of low concentration of BPR0C261 and X-rays caused a synergistic radiosensitizing effect on NSCLC cells. Additionally, we found that a low concentration of BPR0C261 was sufficient to induce DNA damage in these cells, and it increased the level of DNA damage induced by a fractionation radiation dose (2 Gy) of conventional radiotherapy. Furthermore, the p53 protein level of A549 cell line was upregulated by BPR0C261. On the other hand, the expression of PTEN tumor suppressor was found to be upregulated in H1299 cells but not in A549 cells under the same treatment. Although radiation could not induce PTEN in H1299 cells, a combination of low concentration of BPR0C261 and radiation could reverse this situation. (4) BPR0C261 exhibits specific anticancer effects on NSCLC cells by the enhancement of DNA damage and radiosensitivity with p53-dependent and p53-independent/PTEN-dependent manners. The combination of radiation and BPR0C261 may provide an important strategy for the improvement of radiotherapeutic treatment.

Simulation for efficiency improvement of a thuilium Q-switched ytterbium-doped all-fiber laser.

We theoretically explore the mechanism in a thulium Q-switched ytterbium-doped all-fiber fiber laser using a set of rate equations to model the correlations between the photons and the five energy levels of thulium involved in the Q switching mechanism. We demonstrate that by coupling with a gain-switched resonator, the Q-switched laser is stabilized up to the maximum pulsing rate that is limited by the lifetime of level 3H5. To the best of our knowledge, this is the first study that revealed that level 3H5 plays an essential role in reinitialization, achieving sequential pulses, and limiting the maximum repetition rate.

Vibrio nitrifigilis sp. nov., a marine nitrogen-fixing bacterium isolated from the lagoon sediment of an islet inside an atoll.

A nitrogen-fixing isolate of facultatively anaerobic, marine bacterium, designated strain NFV-1T, was recovered from the lagoon sediment of Dongsha Island, Taiwan. It was a Gram-negative rod which exhibited motility with monotrichous flagellation in broth cultures. The strain required NaCl for growth and grew optimally at about 25-35 °C, 3% NaCl and pH 7-8. It grew aerobically and could achieve anaerobic growth by fermenting D-glucose or other carbohydrates as substrates. NH4Cl could serve as a sole nitrogen source for growth aerobically and anaerobically, whereas growth with N2 as the sole nitrogen source was observed only under anaerobic conditions. Cellular fatty acids were predominated by C16:1 ω7c, C16:0, and C18:1 ω7c. The major polar lipids consisted of phosphatidylethanolamine and phosphatidylserine. Strain NFV-1T had a DNA G + C content of 42.5 mol%, as evaluated according to the chromosomal DNA sequencing data. Analyses of sequence similarities and phylogeny based on the 16S rRNA genes, together with the housekeeping genes, gyrB, ftsZ, mreB, topA and gapA, indicated that the strain formed a distinct species-level lineage in the genus Vibrio of the family Vibrionaceae. These phylogenetic data and those from genomic and phenotypic characterisations support the establishment of a novel Vibrio species, for which the name Vibrio nitrifigilis sp. nov. (type strain NFV-1T = BCRC 81211T = JCM 33628T) is proposed.

Label-Free Characterization of Collagen Crosslinking in Bone-Engineered Materials Using Nonlinear Optical Microscopy.

Engineered biomaterials provide unique functions to overcome the bottlenecks seen in biomedicine. Hence, a technique for rapid and routine tests of collagen is required, in which the test items commonly include molecular weight, crosslinking degree, purity, and sterilization induced structural change. Among them, the crosslinking degree mainly influences collagen properties. In this study, second harmonic generation (SHG) and coherent anti-Stokes Raman scattering (CARS) microscopy are used in combination to explore the collagen structure at molecular and macromolecular scales. These measured parameters are applied for the classification and quantification among the different collagen scaffolds, which were verified by other conventional methods. It is demonstrated that the crosslinking status can be analyzed from SHG images and presented as the coherency of collagen organization that is correlated with the mechanical properties. Also, the comparative analyses of SHG signal and relative CARS signal of amide III band at 1,240 cm−1 to δCH2 band at 1,450 cm−1 of these samples provide information regarding the variation of the molecular structure during a crosslinking process, thus serving as nonlinear optical signatures to indicate a successful crosslinking.

Weissella muntiaci sp. nov., isolated from faeces of Formosan barking deer (Muntiacus reevesi).

A Gram-stain-positive strain, 8 H-2T, was isolated from faeces of Reeves' muntjac (Muntiacus reevesi) barking deer in Taiwan. Cells of the strain were short rod-shaped, non-motile, non-haemolytic, asporogenous, facultatively anaerobic, heterofermentative and did not exhibit catalase and oxidase activities. Comparative analyses of 16S rRNA, pheS and dnaA gene sequences demonstrated that the novel strain was a member of the genus Weissella. On the basis of 16S rRNA gene sequence similarities, the type strains of Weissella oryzae (99.2 %), Weissella confusa (97.8 %), Weissella cibaria (97.6 %) and Weissella soli (97.3 %) were the closest neighbours to strain 8 H-2T. The concatenated housekeeping gene sequence (pheS and dnaA) similarities of 8 H-2T to closely related type strains were 72.5-84.9 %, respectively. The genomic DNA G+C content was 40.5 mol%. The average nucleotide identity and digital DNA-DNA hybridization values with these type strains were 70.2-75.4% and 25.1-30.1 %, respectively. Phenotypic and genotypic test results demonstrated that strain 8 H-2T represents a novel species belonging to the genus Weissella, for which the name Weissella muntiaci sp. nov. is proposed. The type strain is 8 H-2T (=BCRC 81133T=NBRC 113537T).

Vagococcus silagei sp. nov., isolated from brewer's grain used to make silage in Taiwan.

A Gram-stain-positive, coccus- or oval-shaped, non-motile, haemolytic, asporogenous, catalase- and oxidase-negative, and facultatively anaerobic strain, 2B-2T, was isolated from a brewer's grain used to make silage in Taiwan. Comparative analyses of 16S rRNA, hsp60 and pheS gene sequences demonstrated that strain 2B-2T was a member of the genus Vagococcus. On the basis of 16S rRNA gene sequence similarity, the type strains of Vagococcus teuberi (98.4 % similarity), Vagococcus carniphilus (98.4 %), Vagococcus martis (98.2 %), Vagococcus penaei (98.2 %) and Vagococcus fluvialis (98.0 %) were the closest neighbours to this novel strain. The similarity levels of concatenated housekeeping gene sequences (hsp60 and pheS) between strain 2B-2T and these closely related species ranged from 84.5 to 88.0 %. The average nucleotide identity and in silico DNA-DNA hybridization values between strain 2B-2T and its closest relatives were lower than 72.9 and 21.6 %, respectively. The DNA G+C content was 34.7 mol%. Phenotypic and genotypic features demonstrated that strain 2B-2T represents a novel species of the genus Vagococcus, for which the name Vagococcus silagei sp. nov. is proposed. The type strain is 2B-2T (=BCRC 81132T=NBRC 113536T).

Lactobacillus suantsaicola sp. nov. and Lactobacillus suantsaiihabitans sp. nov., isolated from suan-tsai, a traditional fermented mustard green product of Taiwan.

Four Gram-stain-positive strains, R7T, R11, R19T and R27, were isolated from suan-tsai, a traditional fermented mustard green product of Taiwan. Cells were rod-shaped, non-motile, non-haemolytic, asporogenous, facultatively anaerobic, heterofermentative, and did not exhibit catalase and oxidase activities. Comparative analyses of 16S rRNA, pheS and rpoA gene sequences demonstrated that these novel strains were members of the genus Lactobacillus. 16S rRNA and the concatenated pheS and rpoA gene sequence similarities between strains R7T and R11, and strains R19T and R27 were very high (>99.8 % similarity), respectively. On the basis of 16S rRNA gene sequence similarities, the type strains of Lactobacillus paralimentarius (98.5 %), Lactobacillus kimchii (98.5 %), Lactobacillus alimentarius (98.1 %) and Lactobacillus bobalius (98.1 %) were the closest neighbours to strains R7T and R11, and the type strains of Lactobacillus brevis (98.9 %), Lactobacillus cerevisiae (98.4 %), Lactobacillus hammesii (98.4 %), Lactobacillus koreensis (98.4 %) and Lactobacillus yonginensis (98.0 %) were the closest neighbours to strains R19T and R27, respectively. The average nucleotide identity values of R7T and R19T with the closely related type strains were 78.9-80.1% and 75.7-80.5 %, respectively. The digital DNA-DNA hybridization values were 22.8-23.6% and 21.0-23.1 %, respectively. Phenotypic and genotypic test results demonstrated that these strains represent two novel species of the genus Lactobacillus, for which the name Lactobacillus suantsaicola sp. nov. (R7T=BCRC 81127T=NBRC 113530T) and Lactobacillus suantsaiihabitans sp. nov. (R19T=BCRC 81129T=NBRC 113532T) are proposed.

Glaciimonas soli sp. nov., a soil bacterium isolated from the forest of a high elevation mountain.

A Gram-negative, psychrophilic bacterium, designated strain GS1T, was isolated from a forest soil sample collected from the West Peak of Mt. Yushan, Yushan National Park, Taiwan. Cells grown in broth cultures were mostly non-motile and non-flagellated, whereas motile cells with monotrichous, subpolar flagella were also observed. The novel strain grew over a temperature range of 4-25 °C with optimum growth at 10-15 °C. It grew aerobically and was not capable of anaerobic growth by fermentation of D-glucose or other carbohydrates. Ubiquinone 8 was the predominant isoprenoid quinone. The major polar lipids comprised phosphatidylethanolamine, diphosphatidylglycerol and dimethylaminoethanol. Cellular fatty acids were dominated by C16:1ω7c (35.2%), C16:0 (19.5%), C18:1ω7c (18.8%) and C17:0ω7c cyclo (15.5%). The DNA G + C content was 49.2 mol% evaluated according to the genomic sequencing data. Strain GS1T shared more than 96.5% 16S rRNA gene sequence similarities with type strains of four Collimonas species (97.2-97.5%), three Glaciimonas species (97.3% for each of the three) and Oxalicibacterium solurbis (96.5%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain GS1T formed a stable genus-level clade with type strains of species in the genus Glaciimonas in the family Oxalobacteraceae and GS1T was an outgroup with respect to these Glaciimonas species. Characteristically, strain GS1T could be easily distinguished from the recognised Glaciimonas species by exhibition of swimming motility with monotrichous, subpolar flagellum in some of the cells, ability to grow in NaCl at 2% but not at 3% and the distinguishable fatty acid profiles. On the basis of the polyphasic taxonomic data from this study, strain GS1T is considered to represent a novel species of the genus Glaciimonas, for which the name Glaciimonas soli sp. nov. is proposed. The type strain is GS1T (= JCM 33275T = BCRC 81091T).

Minimization of Fresnel reflection by anti-reflection fiber Bragg grating inscribed at the fiber ends.

In this paper, we proposed and numerically demonstrated a novel method to effectively minimize Fresnel reflection from a perpendicularly cleaved fiber using a uniform fiber Bragg grating (FBG) inscribed at the fiber end. By matching the reflectivity of an in-line FBG with the reflectivity caused by the glass-air boundary, the FBG acts as a virtual boundary, which provides destructive interference and suppresses Fresnel reflection. We achieved an anti-reflection FBG with a return loss of more than 80 dB by ensuring that the product of the index contrast and grating period number is almost constant, with a value of 0.2695.

Dongshaea marina gen. nov., sp. nov., a facultatively anaerobic marine bacterium that ferments glucose with gas production.

Two isolates of heterotrophic, facultatively anaerobic, marine bacteria, designated DM1 and DM2T, were recovered from a lagoon sediment sample of Dongsha Island, Taiwan. Cells were Gram-reaction-negative rods. Nearly all of the cells were non-motile and non-flagellated during the late exponential to early stationary phase of growth, while a few of the cells exhibited motility with monotrichous flagellation. The two isolates required NaCl for growth and grew optimally at about 30 °C, 2-3 % NaCl and pH 7-8. They grew aerobically and could achieve anaerobic growth by fermenting d-glucose or other carbohydrates with production of acids and the gases, including CO2 and H2. Ubiquinone Q-8 was the only respiratory quinone. Cellular fatty acids were predominated by C16 : 0, C18 : 1ω7c and C16 : 1ω7c. The major polar lipid was phosphatidylethanolamine. Strains DM1 and DM2T had DNA G+C contents of 52.0 and 51.8 mol%, respectively, as determined by HPLC analysis. Phylogenetic analyses based on 16S rRNA gene sequences clearly indicated that the two isolates formed a distinct genus-level lineage in the family Aeromonadaceae of the class Gammaproteobacteria and was an outgroup with respect to a stable supragenic clade comprising species of the genera Oceanimonas, Oceanisphaera and Zobellella. The phylogenetic data and those from chemotaxonomic, physiological and morphological characterizations support the establishment of a novel species and genus inside the family Aeromonadaceae, for which the name Dongshaea marina gen. nov., sp. nov. is proposed. The type strain is DM2T (=BCRC 81069T=JCM 32096T).

Effects of Alkali Cations and Halide Anions on the Self-Assembly of Phosphatidylcholine in Oils.

The interactions between ions and phospholipids are closely associated with the structures and functions of cell membrane. Instead of conventional aqueous systems, we systematically investigated the effects of inorganic ions on the self-assembly of lecithin, a zwitterionic phosphatidylcholine, in cyclohexane. Previous studies have shown that addition of inorganic salts with specific divalent and trivalent cations can transform lecithin organosols into organogels. In this study, we focused on the effect of monovalent alkali halides. Fourier transform infrared spectroscopy was used to demonstrate that the binding strength of the alkali cations with the phosphate of lecithin is in the order Li+ > Na+ > K+. More importantly, the cation-phosphate interaction is affected by the paired halide anions, and the effect follows the series I- > Br- > Cl-. The salts of stronger interactions with lecithin, including LiCl, LiBr, LiI, and NaI, were found to induce cylindrical micelles sufficiently long to form organogels, while others remain organosols. A mechanism based on the charge density of ions and the enthalpy change of the ion exchange between alkali halides and lecithin headgroup is provided to explain the contrasting interactions and the effectiveness of the salts to induce organogelation.

Passively cascade-pulsed erbium ZBLAN all-fiber laser.

We propose and numerically demonstrate a cascade pulsing mechanism in a CW-pumped Er³âº:ZBLAN all-fiber laser system. In the design, the laser was pumped at 980 nm and passively Q-switched at 1.6 µm. The Q-switched resonance reduced the population on 4/13/2 of the erbium gain fiber, thereby creating a population inversion between the levels of 4/11/2 and 4/13/2, and instantly inducing an intense gain-switched pulse at 2.7 µm. Sequential 2.7-µm single-mode pulsing with a pulse energy of 170 µJ and a peak power of 6 kW was achieved with an absorbed pump power of 0.65 W.

Lensless intracavity focusing in a passively Q-switched all-fiber laser using the mode-field-area mismatch.

Intense lensless intracavity focusing in a saturable absorber Q-switched all-fiber laser resonator by use of loss arrangement and mode-field-area mismatch between the fibers is investigated for the first time. The intracavity power distribution was related to the locations and values of the cavity losses as the saturable absorption loss, the reflection loss of the output coupler, and the splicing loss between the gain fiber and the absorber fiber. With a mode-field-area mismatch and a reduced splicing loss with the gain fiber, a power density in the absorber fiber was achieved that was 11.9 times higher than that in the gain fiber.