Dietary Probiotic Bacillus licheniformis TC22 Increases Growth, Immunity, and Disease Resistance, against Vibrio splendidus Infection in Juvenile Sea Cucumbers Apostichopus japonicus

In this study we examined the effects of probiotic Bacillus licheniformis TC22 on growth, immunity, and disease resistance against Vibrio splendidus in juvenile sea cucumbers Apostichopus japonicus. For 30 days, sea cucumbers were fed diets with TC22 at 0 (control), 105, 107, and 109 CFU/g respectively. Results showed that dietary TC22 at 109 CFU/g significantly improved (P0.05). Dietary TC22 at 109 CFU/g significantly improved phagocytosis, and total nitric oxide synthase activity in sea cucumbers (P0.05). Respiratory burst in sea cucumbers fed dietary TC22 at 109 CFU/g was significantly higher than those fed dietary TC22 at 107 CFU/g (P<0.05). Cumulative mortality after V. splendidus challenge decreased significantly in the sea cucumbers fed with TC22 at 109 CFU/g (P<0.05). The present study confirmed dietary B. licheniformis TC22 at 109 CFU/g could significantly improve immunity and disease resistance in juvenile A. japonicus

Theoretical and Experimental Analysis of the Directional RI Sensing Property of Tilted Fiber Grating

In this article, we have theoretically and experimentally investigated the unique vector refractive index (RI) sensing property of tilted fiber grating (TFG). Due to the orthogonal symmetric grating structure, TFGs would mainly achieve the coupling between the fiber core mode and the two orthogonal polarization LP1m of cladding mode. And the numerical simulation results showed that the coupling coefficient between fundamental core mode to the LP1m cladding mode is higher than the others. In the experiment, we have furthermore observed the cladding mode field distribution of excessively TFG (Ex-TFG) and long period fiber grating (LPFG), which indicated that the evanescent field distribution of cladding mode of TFG shows an asymmetric near field distribution with two lobes oriented along the fast axis of TFG, and the one of LPFG has a circularly symmetric cladding mode field distribution. In addition, by employing side-immersion method, we have measured the azimuth RI sensitivities of Ex-TFG, tilted fiber Bragg grating (TFBG) and LPFG, which exhibited that both Ex-TFG and TFBG have shown a direction-dependency RI sensitivity, and the RI sensitivity with side-immersion along fast axis is almost half of the one along slow axis, and the RI sensitivity of LPFG is azimuth independent. Overall, the experiment results show that the TFGs inherently show unique directional RI sensing property, which could be potentially applied in vector sensing area

Highly polarized multiwavelength er-doped fibre laser using all fibre lyot filter

A multiwavelength Er-doped fibre ring laser system using all fibre Lyot filter and highly nonlinear fibre was experimentally demonstrated, with degree of polarization up to 99.9% and 50 channels output

Hybrid tilted fiber grating based refractive index and liquid level sensing system

We report a refractive index (RI) and liquid level sensing system based on a hybrid grating structure comprising of a 45° and an 81° tilted fiber gratings (TFGs) that have been inscribed into a single mode fiber in series. In this structure, the 45°-TFG is used as a polarizer to filter out the transverse electric (TE) component and enable the 81°-TFG operating at single polarization for RI and level sensing. The experiment results show a lower temperature cross-sensitivity, only about 7.33 pm/°C, and a higher RI sensitivity, being around 180 nm/RIU at RI=1.345 and 926 nm/RIU at RI=1.412 region, which are significantly improved in comparison with long period fiber gratings. The hybrid grating structure has also been applied as a liquid level sensor, showing 3.06 dB/mm linear peak ratio sensitivity

Numerical and experimental analysis of sensitivity-enhanced RI sensor based on Ex-TFG in thin cladding fiber

We report a highly sensitive refractive index (RI) sensor in the aqueous solution, which is based on an 81°-tilted fiber grating structure inscribed into a thin cladding fiber with 40 μm cladding radius. The numerical analysis has indicated that the RI sensitivity of cladding resonance mode of the grating can be significantly enhanced with reducing cladding size. This has been proved by the experimental results as the RI sensitivities of TM and TE resonance peaks in the index region of 1.345 have been increased to 1180 nm/RIU and 1150 nm/RIU, respectively, from only 200 and 170 nm/RIU for the same grating structure inscribed in standard telecom fiber with 62.5-μm cladding radius. Although the temperature sensitivity has also increased, the change in temperature sensitivity is still insignificant in comparison with RI sensitivity enhancement

Multiwavelength Er-doped fiber laser using an all-fiber Lyot filter

We experimentally demonstrated a multiwavelength Er-doped fiber ring laser system by employing an all-fiber Lyot filter (AFLF) and a highly nonlinear fiber (HNLF). The AFLF was employed as a polarizing filter to generate a nonlinear polarization rotation effect and the highly dense and narrow bandwidth comb-like channels. A 1-km-long HNLF was used to enhance the nonlinearity of the laser cavity and suppress the mode competition for multiwavelength operation. In the experiment, 97 laser output channels within a 3 dB bandwidth simultaneously were excited under 224 mW pump power. The power fluctuation of lasing channels was less than 0.182 dB, and the wavelength shift was less than 0.04 nm in 100 min, after treating the AFLF in a thermostatic ice bath. Meanwhile, the output laser was highly polarized with a degree of polarization up to 99.9%

Numerical and Experimental Characterization of Radiation Mode of 45° Tilted Fiber Grating

In this paper, we have numerically and experimentally investigated the radiation mode of 45° tilted fiber grating (45° TFG). By introducing the axial distributions into the volume current method, we have established a three-dimensional theoretical model to analyze spatial distributions of the radiation mode of 45° TFG, and measured the radiation mode spatial distributions in experiment. Both numerical and experimental results show that the radiation mode of 45° TFG exhibits an exponential reduction along the fiber axial direction, and a quasi-Gaussian profile along the radial direction of fiber. Additionally, we have also measured the detailed polarization-dependent azimuthal intensity distributions of radiation modes of both s-and p-polarized core modes. The degree of polarization of radiation mode is around 99.886%, which is independent of the length and the polarization extinction ratio of the grating. Moreover, for the first time, we have experimentally observed a very weak p-polarized component existing in the radiation mode, which has matched well with the simulation results

Excessively tilted fiber grating based Fe3O4 saturable absorber for passively mode-locked fiber laser

A novel approach to saturable absorber (SA) formation is presented by taking advantage of the mode coupling property of excessively tilted fiber grating (Ex-TFG). Stable mode-locked operation can be conveniently achieved based on the interaction between Ex- TFG coupled light and deposited ferroferric-oxide (Fe3O4) nanoparticles. The central wavelength, bandwidth and single pulse duration of the output are 1595 nm, 4.05 nm, and 912 fs, respectively. The fiber laser exhibits good long-term stability with signal-to-noise ratio (SNR) of 67 dB. For the first time, to the best of our knowledge, Ex-TFG based Fe3O4 SA for mode-locked fiber laser is demonstrated

Theoretical and experimental analysis of excessively tilted fiber gratings

We have theoretically and experimentally investigated the dual-peak feature of tilted fiber gratings with excessively tilted structure (named as Ex-TFGs). We have explained the dual-peak feature by solving eigenvalue equations for TM0m and TE0m of a circular waveguide, in which the TE (transverse electric) and TM (transverse magnetic) core modes are coupled into TE and TM cladding modes, respectively. Meanwhile, in the experiment, we have verified that one of the dual peaks at the shorter wavelength is due to the TM mode coupling whereas the other one at the longer wavelength arises from TE mode coupling when a linearly polarized light launched into the Ex-TFG. We have also investigated the peak separation of TE and TM cladding mode for different surrounding medium refractive indexes (SRI), revealed that the dual peaks separation is decreasing as increasing of SRI, which agrees very well with the theoretical analysis results

Variation of Tensor Force due to Nuclear Medium Effect

The enhancement of $J^{\pi}(T)$=3$^{+}$(0) state with isospin $T=0$ excited by the tensor force in the free $^{6}$Li nucleus has been observed, for the first time, relative to a shrinkable excitation in the $^{6}$Li cluster component inside its host nucleus. Comparatively, the excitation of $J^{\pi}(T)$=0$^{+}$(1) state with isospin $T=1$ for these two $^{6}$Li formations take on an approximately equal excitation strength. The mechanism of such tensor force effect was proposed due to the intensive nuclear medium role on isospin $T$=0 state.Comment: 6 pages, 4 figure