Nowadays, the structure of the passive optical networks is evolving, to keep the network survivability, the powering of some elements in this kind of networks is a key issue. In this work we propose the recycling of the Raman pump remaining optical power at the receiver to be converted to electrical power. With a 24 dBm optical pump signal a 8 dB on/off gain over 25 km of single mode optical fiber was achieved. Also, the recycling of the pump signal generated 18.1 mW of electrical power at the receiver. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:116-119, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26506

In this paper, we assess the design and performances of a strictly non-blocking all-optical cross-connect demonstrator node for WDM wavelength path networks. The all-optical cross-connect (AOXC) prototype was experimentally tested in a small 2 x 2 WDM network with a STM-16 bit stream per channel. The single and cascaded performance of the AOXC was also simulated and its results were validated with the experimental ones.

In this paper we propose the application of plastic optical fiber to monitor the concrete curing process. The proposed method is based in the scattering of the propagated optical signal in grooves imposed to the fiber. By monitoring the intensity of the transmitted light signal, along time, we can determine the cement setting rate along all the curing period. The obtained results show that the system has enough sensitivity to analyze a curing period of 28 days, where the received optical power is 5% of the initial value.

The storage capacity of a quick-response (QR) code is limited, which can inhibit several applications. A novel approach to multiplex data to improve the QR code capacity based on colour multiplexing is presented. A model was proposed to determine the recognition rate as a function of the multiplexing density and noise. Experimentally, the increase of the storage capacity by a factor of six times per unit area when compared to the normal QR code is demonstrated.

We study the birefringence in monomodo optical fibres. The propagation degradation mechanism due to the birefringence are analysed. Several models and characterisation techniques used to describe the phenomena and to measure the differential group delay are presented. We used an hybrid technique to measure the differential group delay due to polarisation mode.

We report the investigation of stimulated Brillouin scattering in monomode optical fibres. The physical origins of the process and the analytically models used to describe it are presented. The stimulated Brillouin scattering process in an optical fibre is experimentally characterised and the results compared with simulation ones.

The impact of homodyne and heterodyne crosstalk on an optical signal passing through an optical add drop multiplexer (OADM) node in dense wavelength division multiplexing (DWDM) network is studied, and the analytical expressions for the power penalty are obtain. The statistical impact of crosstalk on signal is studied by simulation and the results compared with experimental data.

Phylogenetically closely related species are often assumed to have similar responses to environmental conditions, but species-specific responses have also been described. These two scenarios may have different conservation implications. We tested these two hypotheses for Prionailurus cats (P. rubiginosus, P. bengalensis, P. viverrinus) in the Indian subcontinent and show its implications on species current protected area coverage and climatic suitability trends through time. We fitted ecological niche models with current environmental conditions and calculated niche overlap. In addition, we developed a model for the Jungle Cat Felis chaus to compare species responses and niche overlap estimates within Prionailurus with those for a related sympatric small cat species. Then we estimated the proportion of current suitable environment covered by protected area and projected climatic models from past (last interglacial) to future (2070; RCP4.5 and RCP8.5) conditions to show implications on population management and conservation. The hypothesis of a similar response and niche overlap among closely related species is not supported. Protected area coverage was lowest for P. viverrinus (mean = 0.071, SD = 0.012) and highest for P. bengalensis (mean = 0.088, SD = 0.006). In addition, the proportion of the subcontinent with suitable climate varied through time and was species-specific. For P. bengalensis, climatic suitability shrunk since at least the mid-Holocene, a trend that can be intensified by human-induced climate warming. Concerning P. viverrinus, most predictions show stable future climatic suitability, but a few indicated potential loss. Climatic suitability for P. rubiginous was predicted to remain stable but the species exhibited a negative association with intensive agriculture. Similar responses to environmental change by phylogenetically closely related species should not be assumed and have implications on protected area coverage and natural trends of species climatic suitability over time. This should be taken into account during conservation and management actions.

We report a molecular modelling paradigm to describe silica polymerization reactions in aqueous solutions at conditions that are representative of realistic experimental processes like biosilicification or porous silica synthesis – i.e. at close to ambient temperatures and over a wide range of pH. The key point is to describe the Si-O-Si chemical bond formation and breakage processes through a continuous potential with a balance between attractive and repulsive interactions between suitably placed virtual sites and sticky particles. The simplicity of the model, its applicability in standard parallelized molecular dynamics codes, and its compatibility with the widely used Martini coarse-grained force-field allows for the study of systems containing millions of atoms over microsecond time scales. The model is calibrated to match experimental results for the temporal evolution of silica polymerization in aqueous solution close to the isoelectric point, and can describe silica polymerization and self-assembly processes during encapsulation of a surfactant micelle.