The Fourier transform relationship between the reflected light from a Bragg grating and the complex spatial modulation of the Bragg grating is used to produce a distributed strain sensing system. A tunable external cavity diode laser along with a reference reflector in an optical fiber are used to produce a measurement of the phase and amplitude of the reflected light from the modulated Bragg grating as a function of wavelength. The system is demonstrated with 22 Bragg gratings in a single fiber on a cantilever beam and compared with foil strain gauge readings.
© 1998 Optical Society of America
Mark Froggatt and Jason Moore, "Distributed Measurement of Static Strain in an Optical Fiber with Multiple Bragg Gratings at Nominally Equal Wavelengths," Appl. Opt. 37, 1741-1746 (1998)