Observation of Replica Holes in Erbium Doped Silica Fiber
Thiago P. Mayer Alegre, Gustavo S. Wiederhecker, Hugo L. Fragnito
Abstract
Abstract We observed for the first time to our knowledge the presence of replica holes in the fluorescencespectrum of EDFA. Saturating the Er 3+ transition at a single wavelength we noticed theappearance of spectral holes in the ASE other than the usual one around the saturating laser. Wequalitatively explain the effect and confront the experimental results with the homogeneouslybroadened model. Introduction One of the limiting factors to state-of-the-art DWDM systems is the effect of Spectral Hole Burning (SHB) inErbium Doped Fiber Amplifiers (EDFAs). It has been already observed that the presence of a saturating signal ina given wavelength induces a hole around the signal in the gain and Amplified Spontaneous Emission (ASE)spectra [1],[2]. These holes in EDFAs are typically between 2 and 8 nm width, which is enough to degrade theneighboring channels. The SHB effect is due to the inhomogeneous broadening of the Er 3+ transitions, causedby site-to-site variations of the local electric field in the silica based host, which induces different ions laser linesproperties.This work shows the existence of spectral holes burned at wavelengths far from the saturating laserline, called Spectral Replica Holes (SRHs). The physical background that explains SRHs is based on theinhomogeneously broadened two-level Stark Splitted