In this letter, an enhanced thermally tunable filter design based on a stack of three layers and a long external sleeve at the tip of a single mode fiber is presented. Here, two of these layers and the sleeve are thermo-sensitive. Moreover, it is shown that by using the sleeve with a large length compared with the thicknesses of the layers, the thermal tuning mechanism can be considerably enhanced. Furthermore, the mathematical model of the enhanced filter is presented and it is experimentally supported. Finally, a tunable single-wavelength erbium doped fiber laser based on this filter was implemented. This laser can be tuned ~19 nm by applying a temperature change of just 2.7°C achieving a resolution of 6.89 nm/°C.

中文翻译：

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增强型热调谐滤光片及其在掺铒光纤激光器中的应用

在这封信中，介绍了一种基于三层堆叠和单模光纤尖端的长外套管的增强型热可调滤波器设计。这里，这些层中的两层和套管是热敏的。此外，表明通过使用与层的厚度相比具有较大长度的套筒，可以显着增强热调谐机制。此外，还提出了增强滤波器的数学模型，并得到了实验支持。最后，实现了基于该滤波器的可调谐单波长掺铒光纤激光器。通过仅施加 2.7°C 的温度变化，该激光器可以调谐 ~19 nm，从而实现 6.89 nm/°C 的分辨率。