Interrogation of a wavelength tunable fiber Bragg grating sensor based ring laser for dynamic strain monitoring

Oluwaseyi Balogun*, Yinian Zhu, Sridhar Krishnaswamy

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


Fiber Bragg gratings (FBGs) are wavelength selective optical reflectors with excellent strain sensitivity and small sensing footprint, which makes them suitable as diagnostic sensors for structural health monitoring applications. In this work, we explore the narrowband wavelength selectivity of FBGs for optical feedback in a tunable fiber ring laser. The fiber ring laser consists of an erbium doped fiber laser that is pumped with a Raman laser (980 nm) to produce population inversion and amplified spontaneous emission (ASE) in the C-band. The ASE light is used to illuminate a FBG sensor connected to the ring, and the reflected light from the sensor is fed back into the laser cavity to produce stimulated emission at the instantaneous center wavelength of the sensor. As the wavelength of the sensor shifts due mechanical or thermal strains, the wavelength of the optical output from the ring laser shifts accordingly. By combining the ring laser with a dynamic spectral demodulator for optical readout, the instantaneous wavelength of the ring laser is tracked with high temporal resolution. The fiber ring laser system offers several potential advantages in the diagnostic sensing of mechanical strains for SHM applications including, fully integrated laser and sensor system, high source power levels at the sensor wavelength, narrow spectral line-width, coherent spectral demodulation, and low system costs. In this work, we present experimental results that detail the feasibility of dynamic spectral tuning of the fiber ring laser at frequencies up to hundreds of kilohertz using a single FBG sensing element. Using multiple sensing elements, the fiber ring laser system would allow for active monitoring of dynamic strains in a multi-point sensor array configuration, which is particularly suitable for the localization of high frequency mechanical strains produced by impact loading and cracking events in structures.

Original languageEnglish (US)
Title of host publicationSmart Sensor Phenomena, Technology, Networks, and Systems 2010
StatePublished - Jun 18 2010
EventSmart Sensor Phenomena, Technology, Networks, and Systems 2010 - San Diego, CA, United States
Duration: Mar 8 2010Mar 10 2010

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


OtherSmart Sensor Phenomena, Technology, Networks, and Systems 2010
CountryUnited States
CitySan Diego, CA


  • Dynamic Strain Monitoring
  • Path Imbalanced Optical Interferometer
  • Tunable Laser Source

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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