Ultrahigh-resolution interrogation of a fiber Bragg grating sensor based on higher order four-wave mixing

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.

Theoretical Investigation of an Alcohol-Filled Tellurite Photonic Crystal Fiber Temperature Sensor Based on Four-Wave Mixing

For this study, a temperature sensor utilizing a novel tellurite photonic crystal fiber (PCF) is designed. In order to improve the sensor sensitivity, alcohol is filled in the air holes of the tellurite PCF. Based on the degenerate four-wave mixing theory, temperature sensing in the mid-infrared region (MIR) can be achieved by detecting the wavelength shift of signal waves and idler waves during variations in temperature. Simulation results show that at a pump wavelength of 3550 nm, the temperature sensitivity of this proposed sensor can be as high as 0.70 nm/°C. To the best of our knowledge, this is the first study to propose temperature sensing in the MIR by drawing on four-wave mixing (FWM) in a non-silica PCF.