We demonstrate the operation of a quadrature phase-shifted extrinsic Fabry–Perot fiber-optic sensor for the detection of the amplitude and the relative polarity of dynamically varying strain. Two laterally displaced single-mode fibers inserted within a hollow silica tube form the 90° phase-shifted sensing system. A multimode fiber, placed in the tube facing the two fibers, acts as a reflector, thereby creating an air gap that acts as a Fabry–Perot cavity. A theoretical description of the sensor is given, and its operation as a dynamically varying strain sensor is described. Strain sensitivities of 5.54° phase shift/microstrain cm−1 are obtained.
© 1991 Optical Society of America
Original Manuscript: August 9, 1990
Manuscript Accepted: November 28, 1990
Published: February 15, 1991
Kent A. Murphy, Michael F. Gunther, Ashish M. Vengsarkar, and Richard O. Claus, "Quadrature phase-shifted, extrinsic Fabry–Perot optical fiber sensors," Opt. Lett. 16, 273-275 (1991)