Nano-strain resolution fiber-optic Fabry-Perot sensors compatible with moderate/low resolution VIS-NIR spectrometers

This paper reports on nano-strain resolution fiber-optic Fabry-Perot sensors produced by an improved selective etching method. The presented sensors exhibit high spectral sensitivity, low intrinsic temperature response, small size and mounting comparable to conventional Fiber Bragg gratings. Furthermore, the proposed sensors can be read-out by a combination of cost-efficient and widely available VIS/NIR spectrometers and LEDs used in lighting/automotive applications. A strain resolution of 1 nɛ was demonstrated when using a high-end FBG signal interrogator, while the application of a cost-efficient VIS spectrometer still yielded a strain resolution of about 20-70 nɛ. When applying suitable temperature compensation, absolute measurements with the nano-strain range are also plausible.