A laser-diode-pumped Yb-doped double-clad fiber laser operating in a hybrid Q-switched regime has been demonstrated. With pulsed pump light and stimulated Brillouin scattering of the gain fiber as the Q-switching mechanisms, the laser generated nanosecond pulses with a stable repetition rate. A single-pulse energy of as much as 143.1 microJ with a peak power of 28.6 kW was obtained. Use of an external-cavity diffraction grating in the Littman configuration permitted tuning of the laser wavelength over a 15.7-THz range from 1080 to 1140 nm, and a linewidth of 0.04 nm over the whole tuning range was achieved.
Abstract The inadequate corrosion resistance of aluminum alloys significantly limits their widespread application, thereby necessitating research on enhancing their resistance to corrosion and contamination. Superamphiphobic coatings present a promising solution to mitigate this issue. In this study, spraying technology was employed in conjunction with MAO to create a superamphiphobic composite coating with exceptional corrosion resistance on the surface of 5083 aluminum alloy. The morphology, superamphiphobic characteristics, and corrosion resistance of the material were comprehensively assessed. The corrosion current density of the optimal superamphiphobic composite coating obtained via MAO followed by spraying with modified TiO2 nanoparticles (Icorr = 9.23 × 10-13 A·cm-2) was six and three orders of magnitude lower than that of 5083 aluminum alloy and the unmodified MAO coating, respectively. Furthermore, the coating exhibited a large capacitive arc diameter, enhanced charge-transfer resistance, and high |Z| value at a low frequency (0.01 Hz), signifying its excellent corrosion resistance. Additionally, the coating exhibited superamphiphobic properties with high contact angle (>150°) and low sliding angle (<10°), promoting nonwetting behavior toward various liquids with different surface tensions. This behavior can be attributed to the micro-nanostructure, which significantly enhances surface hydrophobicity and oleophobicity. Moreover, the coating demonstrated dynamic self-cleaning and antisoiling capabilities. These attributes underscored the ability of the coating to exhibit super-repellency, antisoiling performance, ultralow surface energy, and interfacial adhesion forces. Finally, the superamphiphobic composite coating demonstrated noteworthy thermal and chemical stabilities—as evaluated through heat, acid, and alkali resistance tests—thereby affirming its practical viability.
A bidirectionally pumped spectrum pre-sliced multi-wavelength fiber source is presented in the paper. Two 980nm laser diodes (LDs) are engaged to provide the pump power. An optimized double pass Mach-Zehnder interferometer with extinction ratio larger than 41dB is utilized as the comb filter. The extinction ratio of the fiber source is larger than 24.5dB in the whole C band, and almost reaches 29dB at 1530nm. Integral power of each channel is 0.58mW at 1550nm under 112.3mW total pump power. Channel spacing and bandwidth are 0.81nm and 0.30nm, respectively.
The generation of SBS in discrete Raman gain must be considered along with the problem of limited gain per unit pump power when developing a practical Raman amplifier. In this paper, we focus on discrete Raman amplifier with 15 km dispersion compensating fibers (DCFs). The gain saturation of both forward and backward pumping schemes have been considered and compared. As the pump power increased, the SBS threshold decreased and the reflected power increased dramatically. The 7th SBS stokes have been observed when the pump power is 490mW. The experimental results clearly indicate that the SBS effects produced a saturation of the Raman gain.
Nearly 1000-nm broad continuum from 390 nm to 1370 nm is generated in a 2-m long photonic crystal fibre. The maximum total power of supercontinuum is measured to be 60 mW with the pumping power of 800 mW output from a 200-fs Ti:sapphire laser. The evolution of the pumping light into supercontinuum is experimentally studied in detail. It is found that the mechanism for supercontinuum generation has direct relations with Raman effect and soliton effect, and the four-wave mixing plays an important role in the last phase of the supercontinuum generation.
The output characteristics of linear cavity Yb-doped double-clad fiber laser have been studied theoretically and experimentally. Analytical expressions are evaluated for threshold pump power, output power and slope efficiency of the laser under steady state conditions. The expression of minimum of fiber length for designing a linear cavity Yb-doped double-cladding fiber laser has been given. Then, the Yb-doped double-clad fiber laser has been investigated experimentally. By exploiting various output coupler, output power, threshold pump power and the slop efficiency have been measured. Comparison between the experimental results and theoretical data has been performed. They are in good agreement with each other.
The aim was to examine whether the inhibition of selective cyclooxygenase (COX) 2 activation could suppress the development of inflammatory reaction in visceral and subcutaneous abdominal fats of high-fat-induced obese rats.The rats were fed separately regular diet (CONT), high-fat diet ad libitum or energy-restrictedly (HFr) for 12 weeks. Rats fed high-fat diet ad libitum were further divided into those co-treated with vehicle (HFa), a selective COX2 inhibitor-celecoxib (HFa-Cel) or nimesulide (HFa-Nim). Oral glucose tolerance test (OGTT) was performed at the end of weeks 4, 8, 12. Another set of rats with similar grouping was divided into those with a 4-, 8- or 12-week intervention for tissue sampling.Body and epididymal fat weights were increased similarly in HFa, HFa-Cel and HFa-Nim. Time-dependent increases in plasma insulin, triglyceride, impaired OGTT shown in HFa were significantly reversed in HFa-Cel and HFa-Nim. The obese-linked increases in gene expressions of COX-2, monocyte chemoattractant protein-1 (MCP-1) and tumour necrosis factor-alpha (TNF-alpha) in epididymal and subcutaneous fats (especially in the former) were significantly suppressed in HFa-Cel and HFa-Nim. The protein contents of MCP-1 and TNF-alpha in epididymal fats were changed consistently with their gene expressions. Plasma MCP-1 was increased time-dependently in HFa and suppressed in HFa-Cel and HFa-Nim. The increased CD68 positive cells showed in both epididymal and subcutaneous fats of HFa were significantly attenuated in HFa-Cel and HFa-Nim.Our findings suggest that COX2 activation is crucially involved in the development of inflammatory response in adipose tissues of high-fat-induced obese rats.
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