Suppression of Amplified Spontaneous Emission in Erbium Doped Fiber with Long Period Grating written in it

In this paper we have studied the effect on amplified spontaneous emission (ASE) in erbium doped fiber (EDF) with long period grating (LPG) written in it. Since an LPG is a phase sensitive device, we have added the generated spontaneous emission amplitude with a random phase at each section of the EDF. In order to validate this approach, we have compared the results obtained for the EDF in absence of LPG using our approach with those obtained by the standard power coupled equations. In the presence of the grating in addition to usual gain flattening and enhancement in average gain in the 1540-1560 nm band, there is a significant suppression in backward ASE, and flattening of forward ASE spectrum.