Random laser emission at 1064 and 1550†nm in a Er/Yb co-doped fiber-based dual-wavelength random fiber laser.

Dual-wavelength fiber lasers operating with a wide spectral separation are of considerable importance for many applications. In this study, we propose and experimentally explore an all-fiberized dual-wavelength random fiber laser with bi-directional laser output operating at 1064 and 1550 nm, respectively. A specially designed Er/Yb co-doped fiber, by optimizing the concentrations of the co-doped Er, Yb, Al and P, was developed for simultaneously providing Er ions gain and Yb ions gain for RFL. Two spans of single mode passive fibers are employed to providing random feedback for 1064 and 1550 nm random lasing, respectively. The RFL generates 5.35 W at 1064 nm and 6.61 W at 1550 nm random lasers. Two power amplifiers (PA) enhance the seed laser to 50 W at 1064 nm with a 3 dB bandwidth of 0.31 nm and 20 W at 1550 nm with a 3 dB bandwidth of 1.18 nm. Both the short- and long-term time domain stabilities are crucial for practical applications. The output lasers of 1064 and 1550 nm PAs are in the single transverse mode operating with a nearly Gaussian profile. To the best of our knowledge, this is the first demonstration of a dual-wavelength RFL, with a spectral separation as far as about 500 nm in an all-fiber configuration.

Evaporation characteristics of Er3+-doped silica fiber and its application in the preparation of whispering gallery mode lasers.

In this work, the concentration of rare-earth ions in doped silica whispering gallery lasers (WGLs) is controlled by evaporation. The fabrication of WGLs is used to experimentally evaluate the evaporation rate (mol/µm) and ratio (mol/mol) of erbium and silica lost from a doped fiber during heating. Fixed lengths of doped silica fiber are spliced to different lengths of undoped fiber and then evaporated by feeding into the focus of a CO2 laser. During evaporation, erbium ions are precipitated in the doped silica fiber to control the erbium concentration in the remaining SiO2, which is melted into a microsphere. By increasing the length of the undoped section, a critical point is reached where effectively no ions remain in the glass microsphere. The critical point is found using the spectra of the whispering gallery modes in microspheres with equal sizes. From the critical point, it is estimated that, for a given CO2 laser power, 6.36 × 10-21 mol of Er3+ is lost during the evaporation process for every cubic micron of silica fiber. This is equivalent to 1.74 × 10-7 mol of Er3+ lost per mol of SiO2 evaporated. This result facilitates the control of the doping concentration in WGLs and provides insight into the kinetics of laser-induced evaporation of doped silica.

PDA modified NIR-II NaEr0.8Yb0.2F4nanoparticles with high photothermal effect.

Polydopamine (PDA)-modified NaEr0.8Yb0.2 F4nanoparticles were synthesized, with strong NIR-II emission, quantum yield of 29.63%, and excellent photothermal performance. Crystal phases and microstructures are characterized. Optical properties such as absorption, NIR-II emission, and light stability are studied, and the luminescence mechanism is discussed in detail. Key factors in NIR-II imaging were evaluated in fresh pork tissue, including penetration depth, spatial resolution, and signal-to-noise ratio (SNR). A high penetration depth of 5 mm and a high spatial resolution of 1 mm were detected. Mice are imaged in vivo afterintravenousinjection. Due to the accumulation of nanoparticles in the liver, high image quality with an SNR of 5.2 was detected in the abdomen of KM mice with hair. The photothermal conversion effect of PDA-modified NPs was twice that of the reported material. These NIR-II nanoparticles have superior optical properties, high photothermal efficiency and low cytotoxicity, and are potential fluorescent probes for further disease diagnosis and treatment.

Kilowatt-level tunable all-fiber narrowband superfluorescent fiber source with 40†nm tuning range.

In this study, we presented a high-power widely tunable all-fiber narrowband superfluorescent fiber source (SFS) by employing two tunable bandpass filters and three amplifier stages. More than 935 W output power is achieved, with a slope efficiency of >75% and a beam quality factor of M2=1.40. The tuning of the narrowband SFS ranges from ∼1045 nm to ∼1085 nm with a full width at half maximum linewidth of less than 0.71 nm. The tunable narrowband SFS stably operates without the influence of parasitic oscillation and self-pulsing effects under maximum power. To the best of our knowledge, this study is the first to demonstrate a widely tunable all-fiber narrowband SFS around 1 µm wavelength region with output power reaching kilowatt-level.

Ultra-low-loss double-cladding laser fiber fabricated by optimized chelate gas phase deposition technique.

By applying an optimized chelate gas phase deposition technique, a Yb/Ce codoped aluminosilicate fiber with ultra-low loss of 1.55 dB/km was successfully fabricated and reported. The fiber showed homogenous distribution of the refractive index and dopant concentration devoid of central dip and clustering. Using the fiber as the amplifier stage, it delivered 1023 W near-single-mode laser output (M2=1.35) with a high slope efficiency of 85.1%, and the fiber temperature was less than 24.2°C, primarily benefiting from the ultra-low background loss. The fiber also exhibited low photodarkening-induced loss, illustrating its outstanding photodarkening resistance. These results indicate that the ultra-low-loss Yb/Ce codoped aluminosilicate fiber is a prospective candidate for stable and reliable fiber laser applications.

Expanded graphite embedded with aluminum nanoparticles as superior thermal conductivity anodes for high-performance lithium-ion batteries.

The development of high capacity and long-life lithium-ion batteries is a long-term pursuing and under a close scrutiny. Most of the researches have been focused on exploring electrode materials and structures with high store capability of lithium ions and at the same time with a good electrical conductivity. Thermal conductivity of an electrode material will also have significant impacts on boosting battery capacity and prolonging battery lifetime, which is, however, underestimated. Here, we present the development of an expanded graphite embedded with Al metal nanoparticles (EG-MNPs-Al) synthesized by an oxidation-expansion process. The synthesized EG-MNPs-Al material exhibited a typical hierarchical structure with embedded Al metal nanoparticles into the interspaces of expanded graphite. The parallel thermal conductivity was up to 11.6 W·m-1·K-1 with a bulk density of 453 kg·m-3 at room temperature, a 150% improvement compared to expanded graphite (4.6 W·m-1·K-1) owing to the existence of Al metal nanoparticles. The first reversible capacity of EG-MNPs-Al as anode material for lithium ion battery was 480 mAh·g-1 at a current density of 100 mA·g-1, and retained 84% capacity after 300 cycles. The improved cycling stability and system security of lithium ion batteries is attributed to the excellent thermal conductivity of the EG-MNPs-Al anodes.

[A clinical study of biological zinc for the treatment of male infertility with chronic prostatitis].

OBJECTIVE: To evaluate the efficacy of biological zinc in the treatment of male infertility with chronic prostatitis (MICP). METHODS: Thirty-eight patients with MICP were treated with biological zinc. The zinc concentration in the semen and the seminal parameters were tested before and after using biological zinc. RESULTS: After treatment, the zinc concentration in the semen was increased markedly, and the semen liquefaction and the sperm motility were also improved in the patients who had received biological zinc supplementation as compared with those who had not (P < 0.05). CONCLUSION: It is suggested that biological zinc has the effect of increasing zinc concentration in semen, and the supplementation of biological zinc for one of the effective methods for the treatment of MICP.

[Clinical study of zinc for the treatment of chronic bacterial prostatitis].

OBJECTIVE: To study the efficacy of biological organic zinc in the treatment of chronic bacterial prostatitis (CBP). METHODS: Sixty-one CBP patients were randomized into two groups: Group A (39 cases) was supplemented with organic zinc after routine antibiotic treatment, Group B (22 cases) was given routine antibiotic treatment only. NIH-CPIS (including pain, urinary symptoms, quality of life) and urodynamic indexes were used to evaluate the efficacy of biological organic zinc in the treatment of CBP. RESULTS: The NIH-CPIS (including pain, urinary symptoms, quality of life) and the maximum urethra closure pressure (MUCP) were markedly decreased after the zinc treatment, compared with the non-zinc group(P < 0.05). CONCLUSION: It is suggested that biological organic zinc is effective for the treatment of CBP.

Electromagnetic wave absorbing properties of amorphous carbon nanotubes.

Amorphous carbon nanotubes (ACNTs) with diameters in the range of 7-50 nm were used as absorber materials for electromagnetic waves. The electromagnetic wave absorbing composite films were prepared by a dip-coating method using a uniform mixture of rare earth lanthanum nitrate doped ACNTs and polyvinyl chloride (PVC). The microstructures of ACNTs and ACNT/PVC composites were characterized using transmission electron microscope and X-ray diffraction, and their electromagnetic wave absorbing properties were measured using a vector-network analyzer. The experimental results indicated that the electromagnetic wave absorbing properties of ACNTs are superior to multi-walled CNTs, and greatly improved by doping 6 wt% lanthanum nitrate. The reflection loss (R) value of a lanthanum nitrate doped ACNT/PVC composite was -25.02 dB at 14.44 GHz, and the frequency bandwidth corresponding to the reflector loss at -10 dB was up to 5.8 GHz within the frequency range of 2-18 GHz.