We demonstrate an ultra-compact optical fiber thermo-hygrometer on the base of a bilayer OA (Optical Adhesive, a kind of polymer) micro-cap covering the entire SMF (Single-Mode-Fiber) facet. In fabrication, two types of OA are dispensed to fiber facet successively and stratified distinctly forming the bilayer micro-cap, which contains a flat and 2 spherical interfaces reflecting emitted light. Hence, hybrid interference would occur. The experimental results show that the sensitivity for humidity and temperature reach −3.641deg/%RH and −4.527deg/°C when demodulating interference phase shift, and dual-parameter measurement could also be achieved. The proposed optical fiber thermo-hygrometer is integrated, robust and with high sensitivity, making it satisfy lab-on-tip measuring requirement.

中文翻译：

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基于光纤端面双层微帽的超紧凑型光学温湿度计

我们展示了一种基于双层 OA（光学粘合剂，一种聚合物）微帽覆盖整个 SMF（单模光纤）面的超紧凑型光纤温湿度计。在制造过程中，两种类型的 OA 依次分配到纤维面并明显分层，形成双层微帽，其中包含一个平面和 2 个反射发射光的球形界面。因此，会发生混合干扰。实验结果表明，解调干扰相移时对湿度和温度的灵敏度分别达到-3.641deg/%RH和-4.527deg/°C，还可以实现双参数测量。所提出的光纤温湿度计集成、坚固且具有高灵敏度，使其满足实验室尖端测量要求。