Spectral noise analysis of Er3+:Ti:LiNbO3 curved waveguide amplifiers

We report simulations concerning optical amplification in Er:Ti:LiNbO₃ curved waveguides. The derivation and the evaluation of the spectral optical gain, the spectral noise figure, the amplified spontaneous emission photon number, and the signal to noise ratio are performed under the small gain approximation. The simulations show the evolution of these parameters under various pump regimes, Er concentration profiles and waveguide lengths. The results obtained are of significant interest for the design of complex, rare earth-doped integrated optics structures involving bent waveguides.     

The use of stable isotopes ratios for authentication of fruit juices

The determination of the content of stable isotopes, ¹⁸O and ²H, respectively, in juice water facilitates the distinction between authentic juices and juices made from concentrates by redilution with tap water. At the same time, the detection of C₄ cane or corn-derived sugar syrups in fruit juices which are produced from C₃ fruit types is thus facilitated by the characteristic differences in ¹³C/¹²C, expressed as δ ¹³C (‰) values due to photosynthetic CO₂ assimilation via the C₃₋, C₄₋, and crassulacean acid metabolism pathways. In this study, the quantitative determination of water added to an authentic juice, on the basis of δ ¹⁸O, and δ ²H values, respectively, was successfully performed. Also, the δ ¹⁸O, and δ ²H of juice water and δ ¹³C of the whole juice in 18 samples were also determined. The results obtained provided us with the possibility of distinguishing between authentic fruit juices and those obtained by redilution of concentrated fruit juices and the detection of C⁴ type added sugar.     

Supermode resonances in a multi-core holey fiber-based sensor

We report experimental research of the laser-produced indium plasma in hydrogen, argon and residual atmospheric ambient conditions. Note on general plasma behavior and morphology is presented. On the basis of intensity ratio of the two intense neutral resonance spectral lines (In I 410.2 nm and 451.1 nm), self-absorption was found to be almost negligible in case of argon environment at a pressure of 6650 Pa. Under these conditions, the first Stark widths (W) and shifts (d) measurements were performed as well. The resulting synthetic Lorentz profiles, based on the hyperfine structure of these two lines and corresponded W values, were calculated in order to reproduce measured W _m in case of particular electron temperature (T) and number density (N). These results should be of interest to the upcoming theoretical calculations concerning neutral indium spectral lines and also for various diagnostic applications.     

Stable isotopes determination in some Romanian fruit juices

The characterisation of 45 Romanian single-strength fruit juices (apples, pears, plums and grapes) collected from different Transylvanian areas by means of stable isotope approach are presented and discussed in this study. We measured (2)H/(1)H, (18)O/(16)O ratios from water juice and (13)C/(12)C from pulp and compared these results with those already reported in the literature for single-strength juices, in order to see how the geographical and climatic conditions of Transylvania and the meteorological peculiarities of the year 2010 influence the isotopic composition of the investigated fruit juices. The δ(13)C mean values that we found for apple pulp picked up from different Transylvanian areas show slight differences, probably due to the environmental conditions of the plants. No significant correlation either between the variety of apple or the geographical origin and δ(13)C value was established.     

Evaluation of losses and group effective refractive index of Er3+:Ti:LiNbO3 optical waveguides

In this paper, we report some experimental results concerning several types of loss measurements of Er³⁺:Ti:LiNbO₃ optical waveguides by using optical methods. Using the Fabry-Pérot interferometry method, we evaluated the attenuation coefficient of an optical waveguide resonator for a laser radiation having λ = 1.55 μm. We also evaluated the insertion losses, polarization dependent losses, and coupling with external losses. Additionally, from the transmitted spectra of the symmetrical monomode Fabry-Pérot optical waveguide resonator, we were able to evaluate the value of the group effective refractive index.     

Stable isotopes determination in some Romanian fruit juices

The characterisation of 45 Romanian single-strength fruit juices (apples, pears, plums and grapes) collected from different Transylvanian areas by means of stable isotope approach are presented and discussed in this study. We measured ²H/¹H, ¹⁸O/¹⁶O ratios from water juice and ¹³C/¹²C from pulp and compared these results with those already reported in the literature for single-strength juices, in order to see how the geographical and climatic conditions of Transylvania and the meteorological peculiarities of the year 2010 influence the isotopic composition of the investigated fruit juices. The δ¹³C mean values that we found for apple pulp picked up from different Transylvanian areas show slight differences, probably due to the environmental conditions of the plants. No significant correlation either between the variety of apple or the geographical origin and δ¹³C value was established.     

Direct observation of phase transitions by time-resolved pyro/reflectometry of KrF laser-irradiated metal oxides and metals

New experimental results are obtained by coupling both time-resolved reflectivity and rapid infrared pyrometry under a hemispherical reactor. The heating source KrF laser beam (28 ns, 248 nm) is homogenized and as for probing, a CW He-Ne laser beam (10 mW, 633 nm) is used.Using both methods infrared pyrometry with an IR detector cooled with liquid nitrogen and sensitive in the spectral range 1-12 μm, and time-resolved reflectivity with a rapid photodiode, we were able to study complex thermodynamic transitions with nanosecond time resolution. Three different materials are studied by varying the KrF fluence (energy/surface) from 100 to 2000 mJ/cm²: thin films melting (Au/Ni), the threshold of plasma formation (Ti), and complex liquid phase segregation under semi-conductor state (ZnO). The formation of a liquid Zn film induced by temperature gradient is well evidenced by our signals. Also melting of thin films irradiated by low laser fluences (less than 500 mJ/cm²) translates the typical thermodynamic behavior. Finally, wide fluence dynamic (400-2000 mJ/cm²) is analyzed in the case of Ti surface, and results show two distinguished regimes: first one bellow 1000 mJ/cm² corresponding to the early stage plasma initiation, and second one over 1000 mJ/cm² to the dynamics of plasma expansion.     

Theoretical analysis of output statistics of Er3+:Ti:LiNbO3 M-mode straight waveguide amplifiers

In this paper we present a theoretical analysis of some statistical parameters which characterize the Er³⁺-doped Ti:LiNbO₃ M-mode straight waveguides. The derivation and the evaluation of the spectral optical gain, the spectral noise figure, the Fano factor, the statistical fluctuation and the spontaneous emission factor are performed under the small gain approximation. The simulations show the evolution of these parameters under various pump regimes and waveguide lengths. The obtained results can be used for the design of complex rare earth doped integrated circuits.     

Characterization of Vegetables by Stable Isotopic and Elemental Signatures

ABSTRACT

109 Romanian parsley, celery and parsnip root, cucumber, vegetable marrow, onion, and pepper samples were characterized by their stable isotope ratios and elemental concentrations in comparison to imported varieties. Organic and conventional agriculture practices were also compared as well as a differentiation between eggplant and peppers grown in greenhouses and those in the field. δ²H values were between ?70.8 and 5.6‰, while the δ¹⁸O values were between ?9.0 and 4.1‰. The δ¹⁵N values for white onions were from 2.8 to 11.1‰. For Romanian organic onions, the carbon isotopic values were lower (?29.2 to ?28.2‰) compared to conventional onions from other countries (?27.8‰ to ?23.8%). Linear discriminant analysis was used to characterize agricultural practices and the geographic origin of the vegetables.     

Theoretical Study of the Statistical Properties of Single- and Double-Pass M-Mode Er3+-Ti:LiNbO3 Straight Waveguide Amplifiers

Abstract

In this article, we report a theoretical study concerning some statistical parameters which characterize the single- and double-pass Er³⁺-doped Ti:LiNbO₃ M-mode straight waveguides. For the derivation and the evaluation of the Fano factor, the statistical fluctuation and the spontaneous emission factor we used a quasi two-level model in the small gain approximation and the unsaturated regime. The simulation results show the evolution of these parameters under various pump regimes and waveguide lengths. The obtained results can be used for the design of complex rare earth-doped integrated circuits.