Interference of wave trains separated out in an inhomogeneous emission spectrum of a superluminescent erbium-doped fibre source has been studied by scanning the wavelength of a spectrum analyser. The results demonstrate that, as the spectral resolution of the spectrum analyser decreases to a level corresponding to a sharp drop in interference fringe visibility relative to its original level, near 100%, fringe visibility becomes dependent on the wavelength in the inhomogeneous spectrum of the source. The reason for this is that, at some characteristic resolution σλ (σλ > 0.5 nm in our case), the coherence time of wave trains is not limited by the spectral resolution of the spectrum analyser and is related to the inhomogeneous spectrum of the source, whose limiting width can be thought of as the homogeneous linewidth in the spectrum of the source. This feature can be used for evaluating homogeneous line broadening.

中文翻译：

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宽带掺fiber光纤光源光谱的均匀展宽

通过扫描光谱分析仪的波长，研究了在超发光掺-光纤源的不均匀发射光谱中分离出的波列的干扰。结果表明，随着频谱分析仪的光谱分辨率降低到与干涉条纹可见性相对于其原始水平的急剧下降相对应的水平，接近100％，条纹可见性变得取决于光源非均匀光谱中的波长。原因是，在某些特征分辨率σλ（在我们的情况下为σλ> 0.5 nm）下，波列的相干时间不受频谱分析仪的频谱分辨率的限制，并且与源的不均匀频谱有关，其极限宽度可以认为是源光谱中的均匀线宽。