Influence of core diameter on the 3-dB bandwidth of graded-index optical fibers

Abstract

Abstract-This paper presents a theoretical investigation on the dispersion in graded-index silica glass fibers under overfilled launching with equal excitation of modes. This theory incorporates both chromatic effect and modal contribution which takes not only the modal delay into account but also the distributed loss and mode-coupling. Random microbends are considered to be the most dominant source of coupling. All index perturbations and intrinsic core diameter variations are assumed to be negligible, but they could readily be included without changing the basic structure of the model. The 3-dB bandwidth is analyzed through the study of the fiber transfer function which introduces the wavelength and modal effects as two separate filter functions. The formal derivation of the chromatic transfer function is analytical. On the other hand, the modal transfer function is obtained by numerically solving the power flow equation in the frequency domain using Crank-Nicholson method. As an application, the results are illustrated showing, in particular, the influence of the fiber core/outside diameters, for the first time.

Impact of chromatic and modal dispersion on frequency response of optical multimode fibers

“…The transfer function of multimode fiber is modelled by two filter function as follow [3]: 850 and 1300nm. The frequency response is equal to 0 dBo for both wavelengths equal to 850, 1300nm.…”

“…We have made out two MMF standards as 50/1251lm and 62.5/125Ilm. For standard 62.5 /125Ilm MMF 's the minimum bandwidths are only specified to be 200 and 500 MHz/km in the 850 and l300nm transmission windows under full-mode launching condition [3]. In this work, we have mainly made a particular attention to graded-index 50/l251lm silica optical MMF fiber used in optical network based in Ethernet protocol , Fibre Channel, FDOl, ATM, and Token Ring protocol.…”

Modeling and Simulation of Piecewise Regular Multimode Fiber Links Operating in a Few-Mode Regime

“…In works [34][35][36], a passage to infinite number of mode components (mode continuum) is proposed followed by replacing the sum of discrete mode component fields by integration. By neglecting core geometry variation, random fiber macrobends is considered as the main factor of mode coupling in [37][38][39]. Also in [40][41][42][43][44] a special curvilinear coordinates are applied to describe mode coupling via fiber bends.…”

Sistemas de banda ancha sobre fibras ópticas multimodo empleando fuentes estrechas y excitación modal central.

“…Como consecuencia de (2.51), el retardo de grupo por unidad de longitud τ µ del modo µ-ésimo depende sólo de su número de grupo modal m. El tiempo de retardo de grupo por unidad de longitud del grupo modal m-esimo puede derivarse de (2.52) mediante la definición dada en [29,56] …”

“…Dichos mecanismos actúan sobre cada modo de un modo diferente, lo que conlleva que el coeficiente de atenuación varíe de un modo a otro. En [29,56] se sugirió emplear la siguiente formula empírica para describir la atenuación modal diferencial (DMA) en potencia…”