Ge-Doped microstructured multicorefiber for customizable supercontinuum generation

Supercontinuum generation in a multicore fiber in which several uncoupled cores were doped with dissimilar concentrations of germanium was studied experimentally. Germanium doping provided control over the separation between the zero-dispersion wavelength and the 1064-nm wavelength of a Q-switched Nd:YAG pump laser. Supercontinua generated independently in each core of the same piece of fiber displayed clear and repeatable differences due to the influence of germanium doping on refractive index and four-wave mixing. The spectral evolution of the subnanosecond pump pulses injected into the different cores was accurately reproduced by numerical simulations

Broadband optical supercontinuum generation in a long cavity fibre laser

We describe optical supercontinuum generation in an actively mode-locked fibre ring laser using a pulsed mode-locking technique. Recirculation of a section of the continuum facilitated spectral broadening

Ge-Doped microstructured multicorefiber for customizable supercontinuum generation

Supercontinuum generation in a multicore fiber in which several uncoupled cores were doped with dissimilar concentrations of germanium was studied experimentally. Germanium doping provided control over the separation between the zero-dispersion wavelength and the 1064-nm wavelength of a Q-switched Nd:YAG pump laser. Supercontinua generated independently in each core of the same piece of fiber displayed clear and repeatable differences due to the influence of germanium doping on refractive index and four-wave mixing. The spectral evolution of the subnanosecond pump pulses injected into the different cores was accurately reproduced by numerical simulations

Four-Wave Mixing in Nonlinear Fiber with Two Intra-Cavity Frequency-Shifted Laser Pumps

We experimentally study Bragg-type four-wave mixing frequency conversion in highly nonlinear fibers by using two independent frequency-shifted-feedback lasers. We obtain frequency conversion with partial coherent pumps when both lasers operate in the continuous-wave regime. Our experimental results compare well with numerical simulations, which take into account partial coherence of the two pumps

Intra-cavity frequency shifted laser pumps for non-degenerate and partially coherent Bragg-Scattering FWM in nonlinear fiber

International audienceIn this work the authors experimentally study the problem of non-degenerate four-wave-mixing (FWM) by using a pair of partially coherent pumps, and focus our attention on a specific type of FWM, which is generally called "Bragg-Scattering" (BS-FWM). This kind of FWM has attracted a renewed interest because of its intrinsically low-noise nature which makes it potentially applicable for light-by-light manipulation even for very faint signals such as quantum keys

[Early laparoscopic cholecystectomy in the treatment of acute cholecystitis].

BACKGROUND: The aim of the study was to demonstrate the importance of early laparoscopic cholecystectomy for acute cholecystitis. METHODS: From 1998 to 2000, 66 patients were submitted to laparoscopic cholecystectomy. All patients were submitted to US scans preoperatively and operated on by surgeon skilled in emergency laparoscopic operative technique. RESULTS: Only one patient (1.5%) had conversion to open cholecystectomy. There was no mortality and no bile duct or major vascular injuries. The overall operative morbidity rate was 3%. The mean postoperative hospital stay was 3.1 days. CONCLUSIONS: Author's experience and results support the validity of early laparoscopic cholecystectomy in the treatment of acute cholecystitis, since it reduces the postoperative length of hospital stay and hospital costs. Early treatment is always helpful for inflamed and oedematous tissue which favours dissection

Bio-P release in the final clarifiers of a large WWTP with co-precipitation: Key factors and troubleshooting

Phosphorus removal by chemical precipitation is a well-established and widely used technique in municipal waste water treatment plants (WWTPs). Very low effluent concentrations can be achieved in order to comply with standards for discharge in sensitive areas, in force in the EU; nevertheless, failures of this system are occasionally recorded. In this work, a 330,000 people equivalent (p.e.) WWTP was studied, where co-precipitation was not effective to guarantee an effluent concentration stably below 1. mg. P/L, despite the great expenditure for chemicals (around 260,000. €/y) and additional sludge disposal (around 160,000. €/y). Based on results of laboratory tests and mathematical simulations, it was shown that bio-P release occurs in final clarifiers under special conditions, related to Sludge Retention Time (SRT) in the settling tanks, Dissolved Oxygen (DO) in nitrification basins and nitrates concentration in the effluent. Therefore, complying with effluent standards should require keeping process conditions as follows: DO. >. 1. mg/L, N-NO3->5mg/L and SRT. <. 3. h. As additional measure, a post-precipitation (required dosage: 4-5. mg. Al/mg. P) could be applied