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):

Report Date:

1991-06-01

Pagination or Media Count:

396.0

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.

Subject Categories:

  • Test Facilities, Equipment and Methods
  • Fiber Optics and Integrated Optics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE