将向列相液晶(E7)与光纤U型腔相结合,通过外加电场对液晶分子进行取向,分别获得了寻常光和非寻常光的干涉光谱,并获得了其不同的温度系数特性。实验发现:在液晶清亮点以下时,随着温度的升高,非寻常光的干涉光谱向短波长方向移动,而寻常光干涉光谱则一般向长波长方向移动;当接近清亮点时,光谱的移动速度加快;在液晶清亮点以上时,偏振相关干涉消失,干涉光谱随温度升高而发生蓝移。进一步推导了液晶的温度系数,理论分析与实验结果一致。该系统具有结构紧凑、集成度高和稳定性好等优点,在液晶的温度效应表征、偏振光学以及光传感等领域中具有良好的应用前景。

Herein, two sets of interference spectra corresponding to the ordinary and extraordinary waves are obtained by combining the nematic E7 liquid crystal (LC) with a U-shaped optical fiber cavity and applying an external electric field to the LC. In particular, their differing temperature characteristics are investigated. Experimental results show that when the temperature is below the LC’s clearing point, the interference spectrum of the extraordinary wave blue-shifts, whereas the spectrum of the ordinary wave generally red-shifts with the increasing temperature. As the temperature approaches the LC’s clearing point, these shifts become increasingly faster. However, when the temperature is above the clearing point, the polarization dependence of the structure vanishes; further, the interference spectrum blue-shifts as the temperature increases. Then, the temperature coefficients of the refractive index in case of the LC are theoretically analyzed, which is consistent with the experimental results. The proposed system is compact, highly integrated, and stable, denoting its considerable potential in fields such as LC temperature characterization, polarization optics, and optical sensing.