Liu Yuhui, Lin Weihao, Hu Jie, Zhao Fang, Yu Feihong, Liu Shuaiqi, Chen Jinna, Liu Huanhuan, Shum Perry Ping, Zhang Xuming
Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
Department of Applied Physics, Hong Kong Polytechnic University, Hongkong 999077, China.
Sensors (Basel). 2023 Jul 24;23(14):6632. doi: 10.3390/s23146632.
The Vernier effect created using an incorporated Lyot-Sagnac loop is used to create an ultra-high sensitivity temperature sensor based on a ring laser cavity. Unlike standard double Sagnac loop systems, the proposed sensor is fused into a single Sagnac loop by adjusting the welding angle between two polarization-maintaining fibers (PMFs) to achieve effective temperature sensitivity amplification. The PMFs are separated into two arms of 0.8 m and 1 m in length, with a 45° angle difference between the fast axes. The sensor's performance is examined both theoretically and experimentally. The experimental results reveal that the Vernier amplification effect can be achieved via PMF rotating shaft welding. The temperature sensitivity in the laser cavity can reach 2.391 nm/°C, which is increased by a factor of more than eight times compared with a single Sagnac loop structure (0.298 nm/°C) with a length of 0.8 m without the Vernier effect at temperatures ranging from 20 °C to 30 °C. Furthermore, unlike traditional optical fiber sensing that uses a broadband light source (BBS) for detection, which causes issues such as low signal-to-noise ratio and broad bandwidth, the Sagnac loop can be employed as a filter by inserting itself into the fiber ring laser (FRL) cavity. When the external parameters change, the laser is offset by the interference general modulation, allowing the external temperature to be monitored. The superior performance of signal-to-noise ratios of up to 50 dB and bandwidths of less than 0.2 nm is achieved. The proposed sensor has a simple structure and high sensitivity and is expected to play a role in biological cell activity monitoring.
利用集成的利奥-萨尼亚克环产生的游标效应来创建基于环形激光腔的超高灵敏度温度传感器。与标准的双萨尼亚克环系统不同，所提出的传感器通过调整两根保偏光纤（PMF）之间的焊接角度融合到单个萨尼亚克环中，以实现有效的温度灵敏度放大。保偏光纤被分成两个长度分别为0.8米和1米的臂，快轴之间的角度差为45°。从理论和实验两方面对该传感器的性能进行了研究。实验结果表明，通过保偏光纤旋转轴焊接可以实现游标放大效应。在20℃至30℃的温度范围内，激光腔内的温度灵敏度可达2.391纳米/℃，与长度为0.8米且无游标效应的单个萨尼亚克环结构（0.298纳米/℃）相比，提高了八倍多。此外，与传统的使用宽带光源（BBS）进行检测的光纤传感不同，宽带光源会导致诸如信噪比低和带宽宽等问题，萨尼亚克环可以通过插入光纤环形激光器（FRL）腔中用作滤波器。当外部参数变化时，激光会因干涉通用调制而偏移，从而可以监测外部温度。实现了高达50 dB的卓越信噪比和小于0.2纳米的带宽。所提出的传感器结构简单、灵敏度高，有望在生物细胞活性监测中发挥作用。
