International Journal of Advanced Engineering Research and Science (IJAERS) [Vol-1, Issue-5, Oct- 2014] ISSN: 2349-6495 Page | 111 Harmful Thermal Radiation and Bending Effects on Power Attenuations in Deformed Plastic Optical Fibers Ahmed Nabih Zaki Rashed 1 , A. Abd El-Naser Mohamed 2 , Imbaby I. Mahmoud 3 , , Mohamed S. El_Tokhy 4 , Osama H. Elgzar 5 1,2 Electronics and Electrical Communication Engineering Department, Faculty of Electronic Engineering, Menouf, 32951, Egypt 3,4,5 Engineering Department, Nuclear Research Center, Atomic Energy Authority, P.O. 13759, Inshas, Egypt Abstract—Radiation and temperature influence the optical fiber characteristics. These influences such as increasing the power loss were studied and shown to result from the refractive index changes occurring within the fibers induced by bending and thermal effects. In this paper we present a model and a simulation results to reveal the effect of radiation and temperature on the bent polymer optical fiber by using Vissim environment. We demonstrate the importance of operating wavelength and optical fiber parameters in the reduction of the power losses. This formulated treatment provides a mean to control the optical characteristics of fibers in radiation environments. The results are validated against published experimental work and showed good agreement. Keywords─ Gamma radiation, thermal irradiation effect, critical bend radius parameters, polymer optical fiber, power loss. I. INTRODUCTION The growth of internet traffic in the past decade has led to an increasing demand for data transmission capacity media even in local area networks (LANs) and home networks [1]. Optical fiber is the basic element in the modern high capacity and high-bit-rate optical telecommunication systems [2-3] There are many types of optical fibers such as glass fibers and plastic fibers [4].Plastic optical fibers (POFs) are being considered for high-performance fiber links at very short distances than silica based fibers because of their ductility, light weight [5], low cost, flexibility and ease of handling and interconnecting [1]. Furthermore they have much higher bandwidth [6] they are resistance to impacts and vibrations [7]. In addition due to the large fiber cross- section of plastic optical fires, connecting to the light source and detector is non-problematic [8-9]. Additionally they are providing reliable data transmission in such diverse fields as industrial and residential local-area networks, home and office applications [10]. However particularly in such local area networks (LANs), many fiber bendings and junctions are inevitable [11]. This result in radiation losses occur at bends in the fiber path. At a bend, the geometry of the core-cladding interface changes and some of the guided light is transmitted from the core into the cladding [12-13]. Zubia and Arrue studied the effects of bending on the power attenuation of POFs and found that the radiation losses observed in bent fibers are a result primarily of refraction of the meridional rays [14]. The average plastic-energy density (APED) accumulated in a deformed POF could result in radiation loss and scattering loss. However it provides a key index for evaluating the power loss in the deformed fiber [14]. Furthermore due to plastic optical fiber advantages it is being considered for use in many systems. Many of these applications require operation in nuclear radiation environments. That is commonly known as it introduces a highly damaging to optical waveguides [15]. Furthermore radiation induced effects in materials and devices are evaluated based on the energy losses resulting upon the interaction between highly energetic radiation and matter [16-18]. Thus when the polymer is subjected to ionizing radiation, it undergoes several changes in its physical and chemical structures induced by radiation, leading to cross linking and scission of molecules phenomena that occur simultaneously, and one of them prevails over the other depending on various factors, such as, material type, irradiation dose and irradiation atmosphere [19-23]. Such polymers are known as degrading polymer [1]. In addition to these effects ionizing radiation will be absorbed, reflected and transmitted in varying degrees, according to the physical properties of the materials on which it falls. The portion which is absorbed will cause a rise in temperature [24]. which plays a significant role in the number of reactions that take place during/after irradiation