Optical Sensing Device Containing Fiber Bragg Gratings

Abstract

A new optical sensing device containing fiber Bragg gratings: a scanning bandpass filter, an interferometer and multiple photodetectors is disclosed. The present invention also describes a new system and method for fibre Bragg grating (FBG) sensor interrogation and multiplexing. The new system combines a scanning Fabry-Perot (SEP) bandpass filter used to wavelength-multiplex multiple gratings in a single fiber, and an unbalanced Mach-Zehnder fibre interferometer made with a 3 x 3 coupler to detect strain-induced wavelength shifts. A passive technique for interferometer drift compensation using non-sensing FBGs is included in the system. A complete prototype system interrogates four gratings in a single fiber at a Nyquist sampling rate up to 10 kHz, with a noise floor measured near 4 nEpsilon Hz-"2 above 0.1 Hz. The inclusion of the interferometer drift compensation technique is shown to make quasi-static measurements feasible.

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Document Details

Document Type
Technical Report
Publication Date
Aug 01, 2000
Accession Number
ADD019963

Entities

People

  • Michael D Todd

Organizations

  • United States Department of the Navy

Tags

Communities of Interest

  • Sensors

DTIC Thesaurus Topics

  • Bandwidth
  • Bragg Gratings
  • Compensation
  • Demodulators
  • Detection
  • Detectors
  • Fiber Bragg Gratings
  • Filters
  • Interferometers
  • Inventions
  • Measurement
  • Multiplexing
  • Optical Detection
  • Optical Detectors
  • Optical Fibers
  • Photodetectors
  • Strain Gages

Fields of Study

  • Physics

Readers

  • Optical Fiber Sensing and Electromagnetic Propagation.
  • Optical Physics and Photonics.