Alicia López

Modeling Methodology for Engineering SI-POF and Connectors in an Avionics System

We introduce a two-step simulation methodology that is used to engineer a typical avionics telecommunication system based on step-index plastic optical fiber (SI-POF). The approach combines a phenomenological model that solves the spatial propagation equation in SI-POF and optical connectors and a time/frequency-domain approach using a commercial simulation tool. SI-POF as well as connectors are characterized using the experiment and a system case study is engineered using the above model. This approach provides a faster and more efficient modeling methodology compared to using the traditional time/frequency-domain approach.

Experimental investigation of optically gain-clamped EDFAs in dynamic optical- burst-switched networks

Feature Issue on Transmission in Optically Transparent Core Networks An experimental investigation of optically gain-clamped Er-doped fiber amplifiers (EDFAs) for application in dynamic burst-switched networks is presented. We characterize the performance of optically gain-clamped EDFAs, in terms of the signal quality of surviving channels with respect to input power variations, as a function of the feedback cavity loss. This is carried out for both a single EDFA as well as cascaded EDFAs in a realistic network scenario, where bursts are asynchronously added and dropped at each node. We show that the optimum feedback cavity loss is not only a function of input power fluctuation and feedback wavelength but also the number of hops through the network.

POF misalignment model based on the calculation of the radiation pattern using the Hankel transform.

Here, we propose a method to estimate misalignment losses that is based on the calculation of the radiated angular power distribution as light propagates through space using the fiber far field pattern (FFP) and simplifying and speeding calculations with the Hankel transform. This method gives good estimates for combined transversal and longitudinal losses at short, intermediate and long offset distances. In addition, the same methodology can be adapted to describe not only scalar loss but also its angular dependence caused by misalignments. We show that this approach can be applied to upgrade a connector matrix included in a propagation model that is integrated into simulation software. This way, we assess the effects of misalignments at different points in the link and are able to predict the performance of different layouts at system level.

Application of the plastic optical fibre in domestic multimedia networks

Plastic optical fibre (POF) constitutes an advantageous alternative medium to implement domestic data networks. In this proposal, we develop an in-home network prototype for distributing video, audio and data information based on large core step-index plastic optical fibres (SI-POF). The aim is to demonstrate a viable uncluttered application of the POFs where the up to date technologies converge in a homogeneous domestic system.

Comparative analysis of the transmission capabilities of large core plastic optical fibres

In this work we characterize the transmission capabilities of several one millimetre diameter plastic optical fibres (POFs) by analyzing their behaviour at a wavelength in the visible range using a bit error rate (BER) measurement system that allows data rate sweeping. We focus our investigation on transmission data rates in the gigabit range and in-home application distances. The data rate limit for each fibre length extracted from our measurements shows that large core plastic optical fibres are suitable candidates for home and office networks. Moreover, conventional step-index plastic optical fibres (SI-POFs) exhibit error free transmission of Gigabit Ethernet (GbE) data over 25 m, which is a reasonable length for in-home applications. However, only the tested graded-index plastic optical fibre (GI-POF) has been able to transmit GbE data at a 50-m length, which could be extended with a lower attenuation fibre.

WDM Ethernet PON based on downstream narrow-FSK modulation

We propose and test experimentally a GbE PON architecture based on downstream narrow-FSK modulation, obtained by direct modulation of a DFB laser and upstream transmission achieved by intensity modulation of the FSK signal within a colorless user terminal.

Attenuation and diffusion produced by small-radius curvatures in POFs

Our aim is to characterize curvatures using a methodology previously applied to other localized disturbances in plastic optical fibers (POFs). The effects of several curvature radii and turn angles have been analyzed, so that for each condition, angular dependent attenuation and diffusion are obtained from experimental measurements to construct a matrix that accounts for the global effects of power loss and mode mixing introduced by the curvature over the angular power distribution. Power loss as a function of bend radius was calculated using the characteristic matrices and compared to experimental results to validate the model. This curvature model can be a useful tool to predict the impact of bends on transmission properties as is demonstrated in the example of a small network in a domestic environment.

Influence of termination on connector loss for plastic optical fibres

We assess the influence of fibre end termination on connector loss for single-core and multi-core plastic optical fibres (POF) using different finishing procedures. Insertion loss for standard ST connectors was measured for fibres from different manufacturers but all with poly-methyl-methacrylate (PMMA) cores, high numerical apertures (NAs) and claddings of 1 mm diameter. We tested single-core fibres with step-index (SI) profiles and a multi-core fibre with 19 cores. We found that the most suitable tool is different depending on the fibre characteristics and that connector insertion loss can be as low as 0.5 dB confirming the high impact of the finishing procedure.

Matrix model of optical power propagation in plastic optical fibres

We present a model of power propagation for step index (SI) plastic optical fibres (POFs) based on the power flow equation generalized to incorporate the temporal dimension. To solve this equation we propose a fast implementation of the finite-difference method in matrix form. The model provides the space-time evolution of the angular power distribution when it is transmitted throughout the fibre which gives a detailed picture of the POFs capabilities for information transmission.

Temperature sensitivity of POF links for avionics applications

We present an experimental study of the temperature sensitivity of three different step-index 1-mm PMMA fibers. Two of these fibers have a special jacket to sustain high temperatures: BH-4001 and LHXE-4001 and the other is a standard, GH-4001 fiber with a polyethylene jacket. We show that the fibers perform well within the manufacturer specified temperature operating ranges. Predictably, higher than specified temperatures can result in permanent damage and permanent performance degradation. This work expands our previous work on modelling POF on various fiber types and lengths, focusing on the short links found on airplanes.