A liquid-level sensor based on the refractive-index sensitivity of long-period fiber-optic gratings is proposed and demonstrated. The form of the transmission spectrum of the long-period grating is dependent on the fraction of the length of the long-period grating that is surrounded by the liquid. The sensor shows a large linear range, with sensitivity of 4.8% change in transmission per millimeter, for a long-period grating with a length of 40 mm and a periodicity of 400mu;m .
© 2001 Optical Society of America
Sarfraz Khaliq, Stephen W. James, and Ralph P. Tatam, "Fiber-optic liquid-level sensor using a long-period grating," Opt. Lett. 26, 1224-1226 (2001)