Abstract

The turning point of the refractive index (RI) sensitivity based on the multimode microfiber (MMMF) in-line Mach–Zehnder interferometer (MZI) is observed. By tracking the resonant wavelength shift of the MZI generated between the ${\mathrm{HE}}_{11}$ and ${\mathrm{HE}}_{12}$ modes in the MMMF, the surrounding RI (SRI) could be detected. Theoretical analysis demonstrates that the RI sensitivity will reach $\pm \infty$ on either side of the turning point due to the group effective RI difference $(G)$ approaching zero. Significantly, the positive sensitivity exists in a very wide fiber diameter range, while the negative sensitivity can be achieved in a narrow diameter range of only 0.3 μm. Meanwhile, the experimental sensitivities and variation trend at different diameters exhibit high consistency with the theoretical results. High RI sensitivity of 10777.8 nm/RIU (RI unit) at the fiber diameter of 4.6 μm and the RI around 1.3334 is realized. The discovery of the sensitivity turning points has great significance on trace detection due to the possibility of ultrahigh RI sensitivity.

© 2015 Optical Society of America

Simultaneous measurement of refractive index and temperature using multimode microfiber-based dual Mach–Zehnder interferometer

Haipeng Luo, Qizhen Sun, Zhilin Xu, Deming Liu, and Lin Zhang
Opt. Lett. 39(13) 4049-4052 (2014)

Highly sensitive vibration sensor based on the dispersion turning point microfiber Mach-Zehnder interferometer

Kaijun Liu, Junhao Fan, Binbin Luo, Xue Zou, Decao Wu, Xianglong Zou, Shenghui Shi, Yufeng Guo, and Mingfu Zhao
Opt. Express 29(21) 32983-32995 (2021)

Refractive index sensor using microfiber-based Mach–Zehnder interferometer

Jianghai Wo, Guanghui Wang, Ying Cui, Qizhen Sun, Ruibing Liang, Perry Ping Shum, and Deming Liu
Opt. Lett. 37(1) 67-69 (2012)

Ultra-high sensitivity of dual dispersion turning point taper-based Mach-Zehnder interferometer

Li-Peng Sun, Tiansheng Huang, Zihao Yuan, Wenfu Lin, Peng Xiao, Mingjin Yang, Jun Ma, Yang Ran, Long Jin, Jie Li, and Bai-Ou Guan
Opt. Express 27(16) 23103-23111 (2019)

Highly sensitive gas refractometers based on optical microfiber modal interferometers operating at dispersion turning point

Nancy Meng Ying Zhang, Kaiwei Li, Nan Zhang, Yu Zheng, Ting Zhang, Miao Qi, Ping Shum, and Lei Wei
Opt. Express 26(22) 29148-29158 (2018)