Fiber Bragg grating strain modulation based on nonlinear string transverse-force amplifier.

The only effective method of fiber Bragg grating (FBG) strain modulation has been by changing the distance between its two fixed ends. We demonstrate an alternative that is more sensitive to force based on the nonlinear amplification relationship between a transverse force applied to a stretched string and its induced axial force. It may improve the sensitivity and size of an FBG force sensor, reduce the number of FBGs needed for multiaxial force monitoring, and control the resonant frequency of an FBG accelerometer.