This paper presents experiment and analysis on variation of temperature sensitivity of resonant modes of a long period grating (LPG) with change in temperature. The theoretical analysis explains the corresponding experimental data on temperature sensitivity of LPGs written in house in Ge-B codoped and H 2 -loaded telecom fiber. The LPGs were first annealed for thermal stability. The average temperature sensitivity of annealed gratings investigated in range 50–300 °C for LPGs in Ge-B codoped fiber and in the range 50–500 °C for LPGs in hydrogenated SMF-28 fiber. The temperature sensitivity increased with temperature. However, the absolute value of temperature sensitivity decreased for LPGs in Ge-B fiber. The analysis shows that the temperature dependence of nonlinear evolution of resonant wavelength is due to second order partial derivatives of differential effective refractive index of a resonant mode with respect to temperature and wavelength. The linearity of temperature sensitivity depends on first and second order partial derivatives of effective refractive indices of core and cladding modes coupled. The study will help in design and development of LPG based devices and sensors operating at elevated temperature.

中文翻译：

---

长周期光纤光栅谐振模式温度灵敏度的温度依赖性

本文对长周期光栅（LPG）谐振模式的温度灵敏度随温度变化的变化进行了实验和分析。理论分析解释了在Ge-B共掺杂和H 2 负载电信光纤中自制LPG的温度敏感性的相应实验数据。液化石油气首先进行退火以获得热稳定性。退火光栅的平均温度灵敏度在 Ge-B 共掺杂光纤中的 LPG 的 50-300 °C 范围内和氢化 SMF-28 光纤中的 LPG 的 50-500 °C 范围内进行研究。温度敏感性随温度升高而增加。然而，Ge-B 光纤中 LPG 的温度敏感性绝对值下降。分析表明，谐振波长非线性演化的温度依赖性是由于谐振模式的微分有效折射率相对于温度和波长的二阶偏导数。温度灵敏度的线性取决于耦合的纤芯和包层模式的有效折射率的一阶和二阶偏导数。该研究将有助于设计和开发在高温下运行的基于液化石油气的设备和传感器。