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A wide-band and flat gain Erbium-doped fiber amplifier (EDFA) is demonstrated using a gain media of high concentration Silica-based erbium doped fiber (EDF). The amplifier has two stages comprising a 1.5 m and 9 m long EDF optimized for C-band and L-band operations respectively, in a double-pass series configuration. The CFBG is used in both stages to allow a double propagation of signal and thus increases the attainable gain in both C- and L-band spectra. At an input signal power of −30 dBm, a flat gain of 22 dB is achieved with a gain variation of ±3 dB within a wide wavelength range from 1530 to 1600nm. The corresponding noise figure varies from 4 to 8 dB within this wavelength region.

A flat gain Erbium-doped fiber amplifier (EDFA) is demonstrated using a gain media of high concentration Silica-based erbium doped fiber (EDF). The amplifier has one stage comprising a 1.5 m and 9 m long EDF optimized for C-band and L-band operations respectively, in a single-pass and double-pass configuration. The CFBG is used at the end of EDF to allow a double propagation of signal and thus increases the attainable gain in both C- and L-band spectra. At input signal power of -30 dB, the averaged flat gain of approximately 25 dB over C-band region and the averaged flat gain of approximately 30 dB over L-band region are achieved by the double-pass amplifier with gain variation approximately ±3 dB. The corresponding noise figure is maintained at 5 dB with noise figure variation ±0.5 dB.

article i nfo Inflammatory reactions in the CNS, resulting from a loss of control and involving a network of non-neuronal and neuronal cells, are major contributors to the onset and progress of several major neurodegenerative diseases. Therapeutic strategies should therefore keep or restore the well-controlled and finely-tuned balance of immune reactions, and protect neurons from inflammatory damage. In our study, we selected plants of the Malaysian rain forest by an ethnobotanic survey, and investigated them in cell-based-assay- systems and in living brain tissue cultures in order to identify anti-inflammatory and neuroprotective effects. We found that alcoholic extracts from the tropical plant Knema laurina (Black wild nutmeg) exhibited highly anti-inflammatory and neuroprotective effects in cell culture experiments, reduced NO- and IL-6-release from activated microglia cells dose-dependently, and protected living brain tissue from microglia-mediated inflammatory damage at a concentration of 30 µg/ml. On the intracellular level, the extract inhibited ERK-1/2- phosphorylation, IkB-phosphorylation and subsequently NF-kB-translocation in microglia cells. K. laurina belongs to the family of Myristicaceae, which have been used for centuries for treatment of digestive and inflammatory diseases and is also a major food plant of the Giant Hornbill. Moreover, extract from K. laurina promotesalso neurogenesis in living braintissue afteroxygen-glucose deprivation. In conclusion, extract from K. laurina not only controls and limits inflammatory reaction after primary neuronal damage, it promotes moreover neurogenesis if given hours until days after stroke-like injury.

We demonstrate the generation of mode-locked pulses from a double-clad ytterbium-doped fiber laser (YDFL) employing a saturable absorber (SA) made of a few layers of black phosphorus (BP). The BP SA was prepared by mechanically exfoliating BP crystal and spreading the acquired BP flakes on a piece of scotch tape. The tape was then sandwiched between two ferrules and incorporated in a YDFL cavity to achieve a stable mode-locked operation at 1085.58 nm with a repetition rate of 13.5 MHz. A maximum pulse energy of 5.93 nJ was obtained at pump power of 1322 mW with the output power of 80 mW. Our study may well be the first demonstration of the BP-based mode-locked fiber laser that should shed some new insights into two-dimensional layer materials related photonics.

The amplification and lasing characteristics of the newly developed Thulium-Ytterbium co-doped fiber (TYDF) are investigated. It is obtained that both TYDF amplifier and laser operate at 1950 nm region. The maximum gain of 22.4 dB is obtained for 1942 nm signal when the 980 nm multimode pump power, TYDF length and input signal power are fixed at 1.2 W, 5 m and -20 dBm, respectively. At 5 m long of TYDF, the laser produces two prominent lines at 1960 nm and 1965 nm with peak powers of 2.8 dBm and 3.1 dBm, respectively due to the nonlinear polarization rotation (NPR) effect in the cavity.