We propose to characterize optical power transmission in stepindex plastic optical fibers by estimating fiber diffusion and attenuation as functions of the propagation angle. We assume that power flow is described by Gloge s differential equation and find a global solution that was fitted to experimental far field patterns registered using a CCD camera as a function of fiber length. The diffusion and attenuation functions obtained describe completely the fiber behavior and thus, along with the power flow equation, can be used to predict the optical power distribution for any condition.

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Abstract-Architectural changes are required at the underlying networks to support the expected Internet data traffic volume growth caused by the popularization of cloud services, 5G-based services, and social networks, whereas providing a highly dynamic connectivity. Cost-effective and energy efficient solutions for flexible network subsystems are required in order to provide future sustainable networks. In this paper, we present a cost-effective DWDM ROADM design enabling optical Metro-Access networks convergence. The cost-effective DWDM ROADM capabilities have been also assessed in an ultra-Dense Wavelength Multiplexing (u-DWDM) Ring Network scenario. In particular, the achievable network throughput has been considered. Index Terms-DWDM; ROADM; Throughput. I. INTRODUCTIONhe ICT eco-system has been rapidly and dramatically changing in the last years. New multimedia and cloud services, the deployment of the Internet of Things (IoT) and the convergence between optical and wireless communications at the 5G paradigm [1] are requiring changes to the networks in order to enable scalable growth in traffic volume, while supporting a high level of dynamic connectivity, full flexibility and increased energy-efficiency. These features can be achieved by considering the cooperation between the network control and data planes. On the one hand, the management and control of networks are evolving towards a Software Defined Networking (SDN)-based centralized architecture (see Fig. 1 accomplished by the subdivision of a DWDM channel into smaller channels called frequency slots (FS) wherein the uplink (U) and the down-link (D) for each user can be established (see Fig. 1). This paper is divided into five sections. Section II presents the proposed cost-effective DWDM Reconfigurable Optical Add-Drop Multiplexer (ROADM) node design, its operation modes and the main advantages of the proposed ROADM architecture. Section III presents the insertion loss, sensitivity and crosstalk measurements and their experimental set-up used for the ROADM characterization. Section IV presents the considered u-DWDM network scenario for proving the cost-effective DWDM ROADM capabilities; an iterative process to design each costeffective DWDM ROADM is proposed in order to obtain the achievable network throughput.Finally, Section V completes the paper with the main conclusions. II. DWDM ROADM NODE ARCHITECTUREThe ROADM design for future Metro-Access converged Networks is basically driven by new network-level requirements, such as full flexibility, adaptability, scalability, resilience and increased energy-efficiency [5]. In order to reach all those features, a new cost-effective

A new type of absorbance-based optical sensor is presented. It is based on a chemical transduction membrane that acts simultaneously as the sensing element and as the light guiding medium. This membrane is inserted between two micromachined waveguides in a silica on silicon structure. Light propagates longitudinally through the membrane, which changes its spectral properties accordingly while interacting with the analyte. As the path length corresponds to the membrane length, not its thickness, high sensitivity can be achieved without an increase of the response time. This paper summarizes the design, the construction, and the validation results obtained with integrated waveguide absorbance optode (IWAO) prototypes. The main advantages of the reported optode are its simple configuration, high sensitivity, and versatility. Experimental results obtained with this IWAO, using a potassium-selective bulk optode, are shown and compared to those obtained with a conventional absorbance device incorporating the same membrane. The optimum membrane thickness of 4 µm gave the lowest light losses (15 dB). The absorbance sensitivities obtained (-0.86 AU/decade) were, as expected, higher than those shown by the conventional device (-0.03 AU/decade), with comparable response times (t 90% ) 0.5 min).

The first prototype of a technologically improved integrated waveguide absorbance optode (IWAO) was developed and tested with a membrane based on a new H+-selective ketocyanine dye and a cadmium ionophore. It was designed with curved instead of rectilinear planar waveguides. Results demonstrated the suitability of the new IWAOs to be employed as sensing platforms, which confer versatility, robustness, and mass production capabilities besides high sensitivity on conventional bulk optodes, as well as the usefulness of such dyes in developing ion-selective membranes in combination with a selective ionophore. The sensor integration as a detector in a flow injection system (FIA) was proposed to obtain an automated, simple, and sufficiently reproducible (RSD <5%) analytical methodology with a sample throughput of 55 h(-1). Very sensitive optodes were obtained, and detection limits on the order of 20 ppb were achieved. Because of the ionophore employed, the optode system showed excellent selectivity over alkali and alkaline-earth metals with the exception of samples containing lead and cadmium ions, where the membrane responded to both analytes. The proposed procedure combines all the advantages of the FIA systems, the simplicity of optical detection, ion recognition selectivity, and sensitivity of ketocyanine dyes, and the features achieved using the integrated device, which comprise an improved sensitivity and short response times as well as robustness, easy handling, and mass production.

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We report on results from the characterization of Stimulated Brillouin Scattering (SBS) spectra for standard single-mode fiber produced by the interaction between two counter-propagating tunable laser sources (TLS) using one as the probe signal to measure and the other as the pump, sweeping a wide span around the signal. Assuming TLS linewidth negligible against SBS gain bandwidth, we measure SBS spectrum for a wide range of pump and probe signal power levels and study the evolution of relevant SBS parameters such as linewidth and gain profile. High signal to noise ratio measurements allows analyzing the evolution of the SBS gain profile from Lorentzian to Gaussian as predicted by current theory of SBS and the use of SBS response for filtering applications.

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