Open AccessHigh-quality Mach–Zehnder interferometer based on a microcavity in single-multi-single mode fiber structure for refractive index sensing
Author(s) -
Yi Liu,
Guoqiang Wu,
Ruifeng Gao,
Shiliang Qu
Publication year - 2017
Publication title -
applied optics
Language(s) - English
Resource type - Journals
ISSN - 0003-6935
DOI - 10.1364/ao.56.000847
Subject(s) - optics , refractive index , mach–zehnder interferometer , materials science , interferometry , femtosecond , graded index fiber , optoelectronics , single mode optical fiber , optical fiber , interference (communication) , fiber optic sensor , laser , physics , telecommunications , channel (broadcasting) , computer science
A fiber inline Mach-Zehnder interferometer (MZI) based on a microcavity with two symmetric openings in single-multi-single mode fiber (SMSF) structure is proposed. By using the finite difference beam propagation method (FD-BPM), the interference spectrum simulation result shows that the MZI can still have high-quality interference even if the microcavity deviates along the radial direction for 3 μm. Therefore, it allows a larger fabrication tolerance and tremendously decreases the fabrication difficulty. Then a microcavity with two symmetric openings in SMSF was fabricated by using femtosecond laser-induced water breakdown. The insertion loss of the microcavity immerged in water is only -8 dB, and the MZ interference peak contrast in the transmission spectrum reaches more than 30 dB. The MZI based on the microcavity in SMSF can be used as a practical liquid refractive index sensor as its high-quality interference spectrum, ultrahigh sensitivity (9756.75 nm/RIU), high refractive index resolution (2×10 -5 RIU), good linearity (99.93%), and low-temperature crosstalk (0.04 nm/°C).