Miniature refractometer based on Mach–Zehnder interferometer with waist-enlarged fusion bitaper

• Main Authors: Ni, Kai, Dong, Xinyong, Chan, Chi Chiu, Li, Tao, Hu, Limin, Qian, Wenwen
• Other Authors: School of Chemical and Biomedical Engineering
• Format: Article
• Language: English
• Published: 2013
• Online Access: https://hdl.handle.net/10356/97467; http://hdl.handle.net/10220/10598
• Institution: Nanyang Technological University

A miniature refractometer by using a Mach–Zehnder interferometer (MZI) in a standard single mode fiber (SMF) with two waist-enlarged fusion bitapers is proposed and experimentally demonstrated. Such an all-fiber SMF-MZI incorporates an intermodal interference between the core mode and cladding modes. Because the cladding modes are sensitive to the external environment, the SMF-MZI is exploited for refractive index measurement. Experimentally, high sensitivity of 266.5 nm/RIU and resolution of 3.75×10^−5 RIU are achieved within a range from 1.346 to 1.4412. The temperature effect of the proposed refractometer is also analyzed.