Accession Number : ADA240062


Title :   Recovering Signals from Optical Fiber Interferometric Sensors


Descriptive Note : Doctoral thesis


Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF ELECTRICAL AND COMPUTER ENGINEERING


Personal Author(s) : Cameron, Charles B


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a240062.pdf


Report Date : Jun 1991


Pagination or Media Count : 396


Abstract : This dissertation examines three methods of recovering signals cheaply from one class of highly sensitive Optical Fiber Interferometric Sensors (OFIS). This class of sensors consists of a laser light source; a 2x2 optical fiber coupler to split the beam in two; a differential transducer which converts a signal of interest into optical phase shift in the laser light transmitted through the two optical fibers in the interferometer; and a 3x3 optical fiber coupler which recombines the two beams, producing interference which can be detected electronically. The three outputs can be operated on symmetrically or asymmetrically to recover the signal of interest. The use of the 3x3 coupler permits Passive Homodyne Demodulation of the phase-modulated signals provided by the interferometer without feedback control or modulation of the laser itself and without requiring the use of electronics within the interferometer. One of the three methods discussed in this dissertation performs symmetric demodulation with analog electronics. Another uses analog-to-digital conversion of the signals and performs asymmetric demodulation in digital hardware. The third method discussed uses asymmetric fringe-rate demodulation. The three methods are characterized by their harmonic distortion, minimum detectable signal, bandwidth, dynamic range, noise, complexity, and approximate cost.


Descriptors :   *ANALOG SYSTEMS , HOMODYNE RADIO RECEIVERS , CONTROL , DIGITAL SYSTEMS , ELECTRONICS , OPTICAL PROPERTIES , DETECTORS , PRESSURE TRANSDUCERS , HARMONICS , PASSIVE SYSTEMS , LASERS , LASER BEAMS , COSTS , LIGHT SOURCES , INTERFEROMETRY , ASYMMETRY , FEEDBACK , SIGNALS , MODULATION , ANALOG TO DIGITAL CONVERTERS , DEMODULATION , DISTORTION , DIFFERENTIAL ANALYZERS , DYNAMIC RANGE , PHASE MODULATION , INTERFEROMETERS , PHASE SHIFT , FIBER OPTICS , OUTPUT


Subject Categories : Test Facilities, Equipment and Methods
      Fiber Optics and Integrated Optics


Distribution Statement : APPROVED FOR PUBLIC RELEASE