We demonstrated a highly sensitive evanescent-wave-based water salinity sensor using a rectangular optical microfiber Sagnac interferometer. The microfiber has a rectangular cross-section with widths of 4.0 μm by 2.5 μm and total length of 36 mm. For water salinity from 0‰ to 40‰, a high sensitivity of 1.95 nm/(1‰) was achieved at the wavelength of 1550 nm, indicating a detection limit of 0.01‰. The proposed sensor has advantages of high sensitivity, compact size, ease for fabrication, and potentially low-cost. It is very useful for undersea applications and manufacture process controlling where monitoring small change in water salinity is required.

Date Published: 2 June 2014
PDF: 4 pages
Proc. SPIE 9157, 23rd International Conference on Optical Fibre Sensors, 915758 (2 June 2014); doi: 10.1117/12.2059626

Published in SPIE Proceedings Vol. 9157:
23rd International Conference on Optical Fibre Sensors
José M. López-Higuera; Julian D. C. Jones; Manuel López-Amo; José Luis Santos, Editor(s)