Abstract
Present work deals with the analytical study of spectral and dispersion properties of long period fiber grating (LPFG) under linear regime. The standard parameters in the understanding of the optical features of an LPFG have been analyzed using the linear coupling processes such that one can appreciate without going through the cumbersome mathematical treatment of coupled mode equations the basic characteristics of the grating. We have analyze transmittance, phase factor, group delay and group velocity dispersion (GVD) of the LPFG as functions of physical parameters like operating wavelength, grating length, induced index change, and detuning parameter. Special attention is paid to the study of GVD with second and third order dispersion contribution as well as the filter characteristics and delay response of the grating. In case of strong grating, we find that at a particular grating strength the resonance band splits into two bands. Negative group delay for certain values of coupling strength suggested that an LPFG can also be used as dispersion compensator in optical fiber communication.
Highlights
In the era of light wave technology, long period fiber gratings (LPFGs) have attracted a great deal of interest because of their importance in designing new optical devices for future need of optical communication and sensing systems
For the first time Vengsarkar et al [1] proposed a new class of fiber grating called long period fiber grating (LPFG) that functions as spectrally selective loss element and acted as inline, low-loss and band-rejection filter
In order to examine the characteristics of the co- propagating core and cladding modes coupled by the grating, following pair of linear coupled mode equations (LCMEs) have been used. [34, 35]
Summary
In the era of light wave technology, long period fiber gratings (LPFGs) have attracted a great deal of interest because of their importance in designing new optical devices for future need of optical communication and sensing systems. The doping metal ion change the effective indices of cladding modes and subsequently the phase matching condition for coupling with the core modes in a long period fiber grating. This technique is applicable in novel filters for a wide band optical communication system. The Introduce of p-phase shift in the middle of the grating opens a band pass within the core-cladding mode resonance peaks These all-fiber filters have the advantages of low insertion loss (
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