Comparing modal noise and FRD of circular and non-circular cross-section fibres
Comparing modal noise and FRD of circular and non-circular cross-section fibres
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比较圆形和非圆形横截面光纤的模态噪声和 FRD
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
A. Jarvinen
中科院分区：
文献类型：
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作者：
D. Sablowski;D. Pluschke;M. Weber;K. Strassmeier;A. Jarvinen
模式噪声是由光纤引入测量的常见噪声源，对于光纤馈电的光谱仪器，特别是高分辨率测量，模式噪声尤为重要。这种噪声源会限制信噪比，危害有限的光子噪声数据。本工作的主题是比较几种常用纤维的模式噪声和焦比退化(FRD)的测量结果。研究了一种简单的机械加扰方法(离中心加扰)对FRD和模式噪声的影响。使用Polymicro Technology(FBP系列)直径为100、200和300μm的圆形和八角形纤维以及CeramOptec的方形和矩形纤维等进行测量。对同一光纤样品的FRD测量是作为波长的函数进行的。此外，我们用八角形代替了特内里费的Stella-Elhelle光谱仪(SES)的环形纤维，发现在678 nm处信噪比增加了1.6倍。实验表明，大幅值低频偏心不会对FRD产生影响，但能有效地降低模态噪声，最高可达180%。(2016Wiley-VCH Verlag GmbH&Co.KGaA，Weinheim)
Modal noise is a common source of noise introduced to the measurements by optical fibres and is particularly important for fibre-fed spectroscopic instruments, especially for high-resolution measurements. This noise source can limit the signal-to-noise ratio and jeopardize photon-noise limited data. The subject of the present work is to compare measurements of modal noise and focal-ratio degradation (FRD) for several commonly used fibres. We study the influence of a simple mechanical scrambling method (excenter) on both FRD and modal noise. Measurements are performed with circular and octagonal fibres from Polymicro Technology (FBP-Series) with diameters of 100, 200, and 300μm and for square and rectangular fibres from CeramOptec, among others. FRD measurements for the same sample of fibres are performed as a function of wavelength. Furthermore, we replaced the circular fibre of the STELLA-echelle-spectrograph (SES) in Tenerife with an octagonal and found a SNR increase by a factor of 1.6 at 678 nm. It is shown in the laboratory that an excenter with a large amplitude and low frequency will not influence the FRD but will reduce modal noise rather effectively by up to 180%. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)