Abstract: As we already know that optical fiber communication is now a days used in the world’s communication network. Optical fiber can be used as a medium for telecommunication over long distances and networking of respective signals as it is light weight and can be bundled in the form of cables. Fiber optics is the only technique known today to have the power to meet the strong demands for flexibility and high bandwidth posed by the rapidly growing communication networks. The optical systems were primarily used in point-to-point long distance links [10]. As long period grating (LPG) is an important component of optical fiber communication system, thus, long period grating can be designed in a effective manner to use it as a important tool to sense the refractive index of any medium. In this paper we have studied about in depth concepts of Long period grating (LPG) and coupled mode equations have been solved for long period grating to analyze the grating structures that exhibit attractive optical properties that make them suitable for optical communication system as a wavelength filter. At the end, we have studied the effect of coupling length on exchange of power and its variation between the core mode and different cladding modes at =1.55µm for a specific set of parameters defined under the observation for a fiber.

Keywords: Optical Fiber, Communication network, Long Period Grating, Coupled Mode analysis, cladding modes, coupling length.