Influence Of LED Optical Characteristic Variations On Performance Of A Plastic Optical Fiber Transmission Link

Abstract

Influence of LED Optical Characteristic Variationson Performance of aPlastic Optical Fiber Transmission LinkE.Moschim, H.Ding, A.Destrez and G.AttalEcole Superieure d'Electricite, Service Radioelectricite et ElectroniquePlateau du Moulon, 91190, Gif sur Yvette, FranceAbstractPlastic optical fiber transmission link (POFTL) becomes an atractive option for short distance LAN's andindustrial applications. In this work, we investigate the influence of LED optical characteristic variationsdue to its junction temperature changements on performances of a PMMA core POFTL. A selective loss As isintroduced for this purpose. The value of As is found to be 0.330/km °C.IntroductionRecently plastic optical fiber transmission link (POFTL) becomes an atractive option for short distanceLAN's and industrial applications, because of its low installation and maintenance cost.] PMMA core plasticfiber, which is actually available on the market, has the following particular properties: its attenuationis 1) high and, 2) very sensitive to light wavelength. As a consequence, the maximal length of; POFTL withoutrepeater is limited to low values and all LED spectral variations will change POFTL performance to anonnegligible level.Our aim is to investigate this effect. We give out in section II some measured optical characteristicvariations of a LED at 660nm due to its junction temperature changements. This kind of LED is well adaptedfor the POFTL applications.2 In section III, a simple POFTL model is proposed. The influence of LED opticalcharacteristic variations on performances of POFTL is examined by introducing a selective loss As. Section IVis our conclusions.II. Optical characteristic variations of a LED at 660nm caused by junction temperature changementAny changement in the junction temperature of a LED will alter its principal optical characteristics: peakemission wavelength, spectrum, emission power and modulation linearity. Junction temperature changements maybe caused by ambient temperature variations or by LED's bias current variations. Several works have beendevoted to this subject.i Here we show only the measured results of a LED at 660nm, which are used in our