Tran, Tuan A.2014-03-142014-03-141991etd-10242009-020318http://hdl.handle.net/10919/45312A surface acoustic wave sensor based on an extrinsic Fabry-Perot interferometer is described. A single-mode fiber, used as the input/output fiber, and a multimode fiber, used mainly as a reflector, form an air-gap that acts as a low-finesse Fabry-Perot cavity. The Fresnel reference reflection from the glass/air interface at the front of the air-gap interferes with the sensing reflection from the air/glass interface at the far end of the air-gap in the input/output fiber. Strains in the silica tube housing the two fibers change the air-gap length, thereby altering the phase difference between the reference and sensing reflections and modulating the output intensity. A theoretical analysis of the interaction between the strain induced by the acoustic fields and the fiber sensor is presented. Because signal drifting in interferometric sensors is common, a dual optical wavelength stabilization technique is also incorporated into the sensor to minimize the effect. Signal to noise ratios (SNR’s) on the order of 39 dB are obtained with a strain sensitivity of 4°/ μstrain cm⁻¹.viii, 76 leavesBTDapplication/pdfenIn CopyrightLD5655.V855 1991.T736Fabry-Perot interferometersInterferometers -- ResearchThesishttp://scholar.lib.vt.edu/theses/available/etd-10242009-020318/