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A simple and robust refractive index (RI) sensor based on a Mach-Zehnder interferometer has been demonstrated. A section of optical microfiber drawn from silica fiber is employed as the sensing arm. Because of the evanescent field, a slight change of the ambient RI will lead to the variation of the microfiber propagation constant, which will further change(More)
We propose a novel fiber Fabry-Perot interferometer (FPI) that incorporates a length of microfiber as its cavity and two fiber Bragg gratings (FBGs) as reflectors. The microfiber FPI is simply fabricated by flame-heated taper-drawing the central spot of an FBG into a section of microfiber. Ambient refractive index (RI) influences the effective index of(More)
A highly sensitive liquid-level sensor based on dual-wavelength single-longitudinal-mode fiber laser is proposed and demonstrated. The laser is formed by exploiting two parallel arranged phase-shift fiber Bragg gratings (ps-FBGs), acting as ultra-narrow bandwidth filters, into a double-ring resonators. By beating the dual-wavelength lasing output, a stable(More)
A distributed Bragg reflector fiber laser-based respiration movement monitoring system has been proposed and experimentally demonstrated. To fabricate the sensing element for respiration monitoring, a fixture that consists of a plastic plate, a section of elastic textile is employed to experience and transfer the belly expansion induced pressure onto the(More)
A novel microstructure based temperature sensor system using hybrid wavelength-division-multiplexing /frequency-division-multiplexing (WDM/FDM) is proposed. The sensing unit is a specially designed microstructure sensor both frequency and wavelength encoded, as well as low insertion loss which makes it have the potential to be densely multiplexed along one(More)
A novel fiber-optic twist sensor based on a dual-polarization distributed Bragg reflector (DBR) fiber grating laser is proposed and experimentally demonstrated. By beating the signal between the two polarizations of the laser which operates at 1543.154 nm, a signal of 30.78 MHz in frequency domain is observed. The twist will change the fiber birefringence,(More)
An improved algorithm named "twice-FFT" for multi-point intrusion location in distributed Sagnac sensing system is proposed and demonstrated. To find the null-frequencies more accurately and efficiently, a second FFT is applied to the frequency spectrum of the phase signal caused by intrusion. After Gaussian fitting and searching the peak response frequency(More)
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