Article Article
Demonstration of a Spectral Profile Multiplexing Algorithm to Demodulate Fiber Bragg Grating Strain Sensors with a Narrowband Light Source

Vertical cavity surface emitting laser (VCSEL) light sources are cheap, lightweight lasers with the potential to serve as light sources in fiber bragg grating (FBG) sensing systems. VCSEL sources are ideal for aerospace nondestructive evaluation applications, where available power may be limited. The drawback to using VCSEL sources for multiplexed sensor arrays is the narrow bandwidth of light that they produce. Currently, this narrow bandwidth limits the number of FBGs that can be multiplexed onto a single fiber. A new signal processing algorithm has been developed using spectral profile multiplexing. The algorithm identifies the wavelength location of individual sensors based on their unique spectral profiles and an evolutionary algorithm used to correlate the measured array spectrum with a predicted one. This work demonstrates the multiplexing of four FBG sensors using a single 0.5 mW VCSEL with modulated current to sweep a 6 nm bandwidth of light. Strain sensing results are also compared with those collected from a commercial high-power interrogator to provide the upper performance limit. The goal of this research was not to outperform the commercial interrogator, but instead to determine how much performance is lost in order to achieve a low-power system. The experimental results demonstrate the potential to use this approach when collecting data from a low-power strain sensor array for material testing; however, they also highlight the importance of noise levels on the quality of strain data obtained and the improved signal processing that would be required to achieve sufficient wavelength location accuracy.


Chapeleau, X, M. Drissi-Habti, and T. Tomonori, 2010, “Embedded Optical Fiber Sensors in Civil Engineering Composite Structures,” Materials Evaluation, Vol. 68, No. 4, pp. 408–415.

Derkevorkian, A., S. Masri, J. Alvarenga, H. Boussalis, J. Bakalyar, and L. Richards, 2013, “Strain-Based Deformation Shape-Estimation Algorithm for Control and Monitoring Applications,” AIAA Journal, Vol. 51, No. 9, pp. 2231–2240.

Duncan, R., B. Childers, D. Gifford, D. Pettit, A. Hickson, J. Duke, and T. Brown, 2003, Use of a Fiber Optic Distributed Sensing System for Nondestructive Testing of Aerospace Structures,” Materials Evaluation, Vol. 61, No. 7, pp. 838–843.

Duncan, R., M. Froggatt, S. Kreger, R. Seeley, D. Gifford, A. Sang, and M. Wolfe, 2007, “High-Accuracy Fiber-Optic Shape Sensing,” Proceedings of SPIE, Vol. 6530, pp. 65301S–65301S–11.

Ferdinand, P., S. Magne, V. Dewynter-Marty, S. Rougeault, and L. Maurin, 2002, “Applications of Fiber Bragg Grating Sensors in the Composite Industry,” MRS Bulletin, Vol. 27, No. 5, pp. 400–407.

Guo, G., D. Hackney, M. Pankow, and K. Peters, 2017, “Interrogation of a Spectral Profile Division Multiplexed FBG Sensor Network using a Modified Particle Swarm Optimization Method,” Measurement Science and Technology, Vol. 28, No. 5, doi: 10.1088/1361-6501/aa637f.

Hackney, D., 2014, “Characterization of Fiber Bragg Gratings as Thermal Sensors in Complex Environments,” Dissertation, North Carolina State University.

Lowder, T., R. Selfridge, and S. Schultz, 2007, “Surface Relief D-Fiber Bragg Gratings for High-Temperature and Multidimensional Bend Sensing,” Materials Evaluation, Vol. 65, No. 10, pp. 1042–1047.

Measures, R., 2001, Structural Monitoring with Fiber Optic Technology, Academic Press, Oxford, UK.

Mizunami, T., S. Hirose, T. Yoshinaga, and K. Yamamoto, 2013, “Power-Stabilized Tunable Narrow-Band Source using a VCSEL And an EDFA for FBG Sensor Interrogation,” Measurement Science and Technology, Vol. 24, No. 9, doi: 10.1088/0957-0233/24/9/094017.

Peters, K., 2009, “Fiber Bragg Grating Sensors,” in C. Boller, F.K. Chang, and Y. Fujino, (eds.), Encyclopedia of Structural Health Monitoring, Vol. 3, Ch. 61, pp. 1097–1112, John Wiley & Sons, Hoboken, NJ.

Schröder, K., W. Ecke, M. Kautz, S. Willett, H. Unterwaditzer, T. Bossel-mann, and M. Rothhardt, 2013, “Smart Current Collector-Fibre Optic Hit Detection System for Improved Security on Railway Tracks,” Measurement Science and Technology, Vol. 24, No. 11, doi: 10.1088/0957-0233/24/11/115104.

Stewart, W., B. Van Hoe, G. Van Steenberge, S. Schultz, and K. Peters, 2015, “Spectral Profile Tracking of Multiplexed Fiber Bragg Grating Sensors,” Optics Communications, Vol. 357, pp. 113–119.

Van Hoe, B., G. Lee, E. Bosman, J. Missinne, S. Kalathimekkad, O. Maskery, D. Webb, K. Sugden, P. Van Daele, and G. Van Steenberge, 2012, “Ultra Small Integrated Optical Fiber Sensing System,” Sensors, Vol. 12, No. 9, pp. 12052–12069.

Yan, L., Z. Wu, Z. Zhang, W. Pan, B. Luo, and P. Wang, 2013, “High-Speed FBG-Based Fiber Sensor Networks for Semidistributed Strain Measure-ments,” IEEE Photonics Journal, Vol. 5, No. 2, doi:10.1109/JPHOT.2013.2258143.

Usage Shares
Total Views
162 Page Views
Total Shares
0 Tweets
0 PDF Downloads
0 Facebook Shares
Total Usage