Two liquid level sensors based on different long-period fiber gratings are proposed and compared. The long-period gratings have the same characteristics (length, grating period) but are fabricated in different optical fibers (photosensitive B-Ge codoped optical fibers with different dopants concentrations). The principle of this type of sensor is based on the refractive index sensitivity of long-period fiber gratings. By monitoring the resonant wavelength shifts of a given attenuation band, one can measure the immersed lengths of long-period fiber gratings and then the liquid level. The levels of two different solutions are measured. The maximum shift (7.69 nm) of the investigated resonance wavelength was observed in LPG1 (fabricated in Fibercore PS1250/1500). By controlling the fiber dopants concentrations one can improve the readouts of a fiber-optic liquid level sensor based on long-period fiber gratings.

Date Published: 29 November 2011
PDF: 6 pages
Proc. SPIE 8307, Passive Components and Fiber-Based Devices VIII, 83070W (29 November 2011); doi: 10.1117/12.904611

Published in SPIE Proceedings Vol. 8307:
Passive Components and Fiber-Based Devices VIII
Bishnu P. Pal, Editor(s)