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实验制备了基于细芯光纤(TCF)的马赫-曾德尔干涉仪(MZI)并进行了多参数测量传感研究。传感器采用两段单模光纤(SMF)进行腰椎放大连接细芯光纤,形成MZI结构。利用TCF与SMF的纤芯直径不匹配,在第1个接点激发出包层模式,包层模在第2个接点耦合进纤芯与纤芯模产生干涉,利用干涉条纹的波长漂移实现对外界环境参量的测量。实验所用的TCF纤芯的掺Ge浓度较高(约为38mol.%),相对折射率和热光系数较普通SMF大,所以在保证适当的自由光谱范围(FSR)的前提下,TCF的长可以减小到2 mm,传感头尺寸较小,且传感结构对于温度的变化十分敏感。实验结果表明,在30~250℃的温度范围内,其温度灵敏度为70.2pm/℃,并具有较好的线性响应度。测试了传感器对折射率、应变和弯曲的响应,获得的灵敏度分别为-8.12nm/RIU、1.8pm/με和2.07nm/m-1。
The Mach-Zehnder interferometer (MZI) based on the fine-core fiber (TCF) was experimentally fabricated and the multi-parameter measurement sensing was carried out. The sensor uses two sections of single-mode fiber (SMF) for lumbar enlargement to connect the fine core fiber to form MZI structure. Using the core diameter of TCF and SMF mismatch, the cladding mode is excited at the first junction, the cladding mode is coupled into the core at the second junction to interfere with the core mode, and the wavelength drift of the interference fringe is utilized to achieve the external Measurement of environmental parameters. The TCF core used in the experiment has a higher doping concentration of Ge (about 38 mol.%) And a higher relative refractive index and thermal coefficient than the conventional SMF. Therefore, the TCF length Can be reduced to 2 mm, sensing head size is small, and the sensing structure is very sensitive to temperature changes. The experimental results show that the temperature sensitivity is 70.2pm / ℃ in the range of 30 ~ 250 ℃, and has a good linear response. The sensors’ response to refractive index, strain and bending were tested and the sensitivities obtained were -8.12nm / RIU, 1.8pm / με and 2.07nm / m-1, respectively.