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Publications (57)
A fiber optic dual-cavity Fabry–Perot interferometer (DFPI) for simultaneous high- temperature and high-gas-pressure measurements is proposed and experimentally demonstrated. The proposed sensing structure consists of an extrinsic Fabry–Perot interferometer (EFPI) with a short piece of hollow core fiber (HCF) for gas pressure sensing, and an intrin...
A phase demodulator for fiber optic extrinsic Fabry-Perot interferometric (EFPI) sensors is proposed for dynamic signal (vibration, acoustic, etc.) measurements. Three interferometric signals with phase differences are introduced by three lasers with different wavelengths. The tangent of the desired dynamic signal is extracted from the three interf...
An on-fiber extrinsic Fabry–Perot interferometric (EFPI) vibration sensor based on micro-cantilever beam is proposed and experimentally demonstrated. The micro-cantilever beam, with a cantilever length of 80μm and a cantilever thickness of 5μm, is created perpendicular to the fiber axis by using the femtosecond laser micro-machining technique. The...
A self-temperature-calibrated gas pressure sensor with a sandwich structure made of single-mode fiber (SMF)-hollow core fiber (HCF)-SMF is proposed and experimentally demonstrated. A Fabry–Perot interferometer (FPI) is formed by the SMF-HCF-SMF structure along the axial direction, and an antiresonant reflecting optical waveguide (ARROW) is formed b...
A fiber optic dual-ring Michelson interferometer (DRMI) based detection scheme for the measurement of dynamic signals is proposed and experimentally demonstrated. The fiber optic sensor is a single mode fiber between two broadband fiber Bragg gratings (FBGs) with different center wavelengths. The two FBGs are connected to two output ports of a
$3...
A symbiosis-Michelson interferometer (SMI)-based detection scheme is proposed and experimentally demonstrated. The SMI comprises a
$3\times 3$
coupler, two FBGs with different center wavelengths, and a common reference arm. Two MIs share a
$3\times 3$
coupler and a reference arm. The sensing part is the fiber between the two FBGs. The sensitivi...
A three-wavelength passive demodulation technique to interrogate extrinsic Fabry-Perot interferometric (EFPI) sensors with arbitrary cavity length has been developed. The DC component is obtained online, then the applied dynamic signal is recovered by using three new signals without the DC component. The performance of the technique is demonstrated...
An extrinsic Fabry-Pérot interferometric (EFPI) sensor created at the tip of an optical fiber is presented for high-pressure measurement. The sensor, with a diameter of 125 μm, is fabricated exclusively in pure silica fiber, which makes it suitable for applications in high-temperature environments. The EFPI cavity of the sensor is formed by fusion...
In this paper, the thermo-optic coefficient of silica fiber is analyzed and measured within a wide temperature range of 0-1200 °C for the first time. To obtain the thermo-optic coefficient, experiments were carried out by using fiber optic extrinsic Fabry-Perot interferometers (EFPIs) embedded in silica fiber. The optical cavity lengths of the EFPI...
A fiber-optic dual-cavity Fabry-Perot interferometric sensor for the simultaneous measurement of temperature and pressure is proposed and experimentally demonstrated. The sensor cascades a fiber-optic intrinsic Fabry–Perot interferometer (IFPI) and an extrinsic Fabry–Perot interferometer (EFPI). The IFPI is used as the temperature sensor and the EF...
Fiber-optic micro vibration sensors fabricated by a femtosecond laser are proposed and experimentally demonstrated. The proposed sensor is an extrinsic Fabry–Perot interferometer (EFPI), which is the three-section structure sandwiched by a single mode fiber (SMF), a hollow core fiber (HCF) and a coreless silica fiber (CF). A femtosecond laser is em...
A fiber-optic hybrid sensor based on dual-cavity Fabry-Perot interferometers is proposed and demonstrated for the simultaneous measurement of high temperature and high pressure. The proposed sensor is fabricated by fusion splicing of two single mode fibers (SMFs), a hollow core fiber (HCF), and a coreless fiber (CF), forming a four-section structur...
A micro all-glass fiber-optic accelerometer based on the extrinsic Fabry-Perot interferometer (EFPI) is developed. A microcantilever beam is fabricated using a femtosecond laser and assembled with a silica tube and a silica inertial mass. Two mirrors, the end face of the leading single-mode fiber and the inner glass/air interface of the cantilever...
A dual-wavelength DC compensation technique for the demodulation of extrinsic Fabry-Perot interferometric (EFPI) fiber sensors is developed. The technique can overcome two problems in the measurement: the cavity length of the EFPI and wavelengths of light sources must be matched, and the DC component of the interferometric fringe must be eliminated...
Five-step phase-shifting white-light interferometry is presented for interrogating the absolute cavity length of the fiber optic extrinsic Fabry–Perot interferometer (EFPI). It combines ideas of phase-shifting interferometry and white-light interferometry (WLI) to extend the measurement range of fiber optic WLI. Five sub-interferograms intercepted...
A compact optical fiber sensor based on a Fabry–Perot interferometer with an integrated fiber Bragg grating is proposed to measure pressure and temperature simultaneously. The light reflectors of the proposed FPI comprise a graphene film and a fiber end face. The sensitivities of the FPI sensor for measuring pressure and temperature are 501.4 nm/kP...
A compact microhole-induced fiber optic inline Mach-Zehnder interferometer (MZI) is demonstrated for measurements of refractive index (RI) and magnetic field. Inline MZIs with different etched diameters, different interaction lengths and different sizes of microholes are fabricated and assessed. The optical transmission spectra of the inline MZIs i...
A compact temperature-compensated fibre optic magnetic field sensor based on a self-referenced anti-resonant reflecting optical waveguide is proposed and experimentally demonstrated. Two hollow holes in the air ring cladding of the hollow core photonic crystal fibre (HCPCF) are infiltrated with magnetic fluid and ethanol. A self-referenced anti-res...
A magnetic fluid (MF)-infiltrated antiresonant reflecting optical waveguide has been fabricated for the magnetic field sensing based on resonant leaky modes. In a hollow core photonic crystal fiber, the MF is selectively infiltrated into one hollow hole in the air cladding. A Fabry-Perot resonator can be formed between the MF and the silica claddin...
To measure the temperature of micro-sized metal film bridge under constant current excitations, by the Fabry-Perot interferometric technology, a new optical fiber sensor was designed for high temperature measurements and quick temperature response. A matched spectrum demodulation system was independently designed and manufactured, including advanta...
A novel humidity sensor based on power leakage at resonance wavelength in a reduced graphene oxide coated hollow core fiber is demonstrated. The reduced graphene oxide is deposited on the outer surface of the hollow core fiber, and a Fabry-Perot resonator is formed in the cladding region. The leaky mode of the guided light can be achieved at resona...
A capillary covered silica hollow core fiber (HCF) has been designed and tested for the measurement of displacement based on antiresonant reflecting optical waveguide. A section of the silica HCF was inserted into a silver coated capillary. A Fabry-Perot resonator can be formed in the silica cladding. The leaky mode of the guided light can be achie...
A compact optical fiber sensor for simultaneous measurement of strain and temperature is designed and experimentally investigated. The proposed sensor consists of a two-peanut-taper Mach–Zehnder interferometer (MZI) and in-line embedded fiber Bragg grating (FBG). The sensor at a length of 35 mm presents strain sensitivities 1.07 pm / με and 0.891 p...
A photonic crystal fiber
(PCF) based high-temperature fiber-optic sensor is proposed and experimentally demonstrated. The sensor head is a Fabry-Perot cavity manufactured with a short section of endless single-mode photonic crystal fiber (ESM PCF). The interferometric spectrum of the Fabry-Perot interferometer is collected by a charge coupled devic...
A high-finesse extrinsic Fabry–Perot interferometric sensor for the measurement of weak dc magnetic fields is demonstrated. The Fabry–Perot cavity is formed by aligning the fiber end-face and the TbDyFe rod end-face, and each end-face is coated by a mirror with a micro-lens. The length of the TbDyFe rod is changed by the variation of an applied dc...
An all-fiber magnetic field sensor by using a TbDyFe rod as the sensing element for the measurement of the weak alternating magnetic field is presented and experimentally demonstrated. The sensor is constructed with a 3 × 3 coupler based Mach–Zehnder interferometer, and the time-varying phase shift induced by the applied magnetic field is recovered...
A sandwich structure between two fiber cores and the magnetic fluid has been designed and tested for the magnetic field detection. The magnetic fluid is clamped between two parallel cores in the photonic crystal fiber. The broadband light is propagated longitudinally with periodical coupling between two parallel cores. Even and odd supermodes with...
A white-light interferometry based on the Fourier transform method is proposed to measure the optical path difference (OPD) of the high-finesse fiber optic extrinsic Fabry–Pérot interferometric (EFPI) sensor. The Fourier spectrum of the transmission spectrum signal consists of multiple frequency components because of the multiple-beam interference...
An in-line photonic crystal fibre-based Mach–Zehnder interferometer (PCF-MZI) with temperature compensation has been proposed and experimentally demonstrated. The in-line PCF-MZI is fabricated by splicing a section of photonic crystal fibre between two single mode fibers. The temperature compensation of the in-line PCF-MZI is realized by using mate...
We present, and experimentally demonstrate, a fiber optic magnetic field sensor for the measurement of a weak alternating magnetic field, based on a TbDyFe rod. The fiber optic magnetic field sensor is constructed in a Michelson interferometer configuration, and the phase-generated carrier demodulation is used to obtain the time-varying phase shift...
The measurement of the diameter change of a piezoelectric transducer (PZT) cylinder with the white-light interferometry is proposed and experimentally demonstrated. One arm of a Mach–Zehnder interferometer (MZI) is wrapped on the PZT cylinder, and the phase change of the interferogram of the MZI is used to determine the diameter change when a DC vo...
An Agarose gel filled photonic crystal fiber in-line interferometric sensor for the measurement of relative humidity is proposed and experimentally demonstrated. The sensor is constructed by filling the Agarose gel between the aligned single mode fiber (SMF) and the photonic crystal fiber (PCF). A fiber in-line interferometer is fabricated by splic...
A miniature fiber-optic temperature sensor that can measure high temperature in a small volume is proposed and experimentally demonstrated. The sensor head is fabricated by splicing a small segment of photonic crystal fiber to the single mode fiber, forming a fiber Fabry-Perot interferometer. A high-speed signal processing method is adopted to meas...
A fiber optic white-light interferometry based on cross-correlation calculation is presented. The detected white-light spectrum signal of fiber optic extrinsic Fabry-Perot interferometric (EFPI) sensor is firstly decomposed by discrete wavelet transform for denoising before interrogating the cavity length of the EFPI sensor. In measurement experime...
Fourier transform white-light interferometry possesses high resolution and wide dynamic range for the absolute measurement of fiber optic interferometric sensors. However, the white-light optical spectrum distributed along wavelength is a chirp signal because the phase of the optical spectrum has a nonlinear relationship with the scanning wavelengt...
A filmed extrinsic Fabry–Pérot interferometric (FEFPI) sensor for the measurement of arbitrary refractive index (RI) is experimentally demonstrated. The FEFPI sensor was constructed by aligning two fiber endfaces, on which the multilayer dielectric mirrors are deposited. There is a fixed reflection at the filmed fiber endface no matter how much the...
A novel method for the measurement of chromatic dispersion (CD) profiles of photonic crystal fibers (PCFs) by using a tip interferometer is presented. A PCF tip interferometer is formed by splicing a short section of the PCF to a single mode fiber. The CD coefficient of the PCF is measured from 1525 to 1565 nm by using the white-light interferometr...
A fibre optic extrinsic Fabry–Perot interferometric (EFPI) displacement sensor for fault measurement in geomechanics is experimentally demonstrated. By using a metal tube and metal bars the EFPI displacement sensor can demonstrate high strength and high stability, as the effects of the harsh environment are mitigated. The sensor is fixed to a long...
A distributed fiber optic pressure sensor based on a piece of the photonic crystal fiber (PCF) is proposed and
experimentally demonstrated. The sensor is fabricated by splicing the PCF with a single-mode fiber (SMF), and the free
end face of the PCF is filmed with a reflectivity of 99%. A Michelson interferometer is formed in the PCF. The pressure...
Fourier transform white-light interferometry recovers the optical path difference of an interferometer by measuring the phase change caused by scanning wavelength. However, the optical spectrum, obtained by wavelength scanning method ( λ -method), contains a chirp in period. The chirp would induce deviation and decrease the measurement accuracy. An...
A novel distributed fiber optic pressure sensor based on an all-solid photonic band gap fiber is proposed and experimentally demonstrated. The sensor is fabricated by splicing a piece of the photonic crystal fiber (PCF) with a single-mode fiber (SMF), and the free end face of the PCF is filmed with a reflectivity of 99%. The cladding mode is excite...
An all-fiber 3x3 coupler based phase-shifted white-light interferometry is
presented, with which the absolute optical path difference (OPD) of a
Mach–Zehnder interferometer can be measured automatically. The
continuous test shows that the variation is ±0.5 µm when measuring a beam length of ~10 m with an OPD of 1847 µm. The technique is successfull...
The precise phase difference in a 3×3 coupler is calculated by using Fourier transform based white-light interferometry. The phase relationships between any two of the three outputs are directly measured, and the result is in agreement with the ideal value. The phase difference of two re-constructed signals in a 3×3 coupler is also measured. In a p...
A phase compensation technique in the fiber optical quadrature passive demodulation scheme is presented. The phase error between the two interferometric signals is calculated first, and a new signal is generated which has an accurate phase difference of 90 degrees with respect to another one. The experimental results show that the distortion in the...
Recent developments in spectral white-light interferometry (WLI) are reviewed. Firstly, the techniques for obtaining optical
spectrum are introduced. Secondly, some novel measurement techniques are reviewed, including the improved peak-to-peak WLI,
improved wavelength-tracking WLI, Fourier transform WLI, and 3 × 3 coupler based WLI. Furthermore, a...
The effect of nonlinear wavelength scanning to Fourier transform white-light interferometry was examined. A Mach-Zehnder interferometer was interrogated, and the absolute optical path difference was measured. The experimental results show that the nonlinearity of the Fabry-Perot tunable filter has no effect on the measurement. A measuring discrimin...
Fiber optic Fourier transform white-light interferometry is presented to interrogate the absolute optical path difference of an Mach-Zehnder interferometer. The phase change of the interferometer caused by scanning wavelength can be calculated by a Fourier transform-based phase demodulation technique. A linear output is achieved.
We have investigated the multiplexing technique of Fourier transform white-light interferometry recently reported by [Jiang IEEE Photon. Technol. Lett. 20, 75 (2008)]. Two extrinsic Fabry-Perot interferometric sensors are spatially frequency-division multiplexed, and no cross talk is found in the experiment. Besides, an improvement was made to achi...
A Fourier-transform phase comparator is developed to measure fiber optic extrinsic Fabry-Perot interferometric sensors. The phase comparator is realized by comparing the phases of two white-light spectra, which are obtained by scanning the wavelength of the light source. The changes of a cavity length, which are concerned in most applications, can...
A four-element fiber Bragg grating acceleration sensor array is presented in this paper. The system combines an unbalanced Mach–Zehnder interferometer and three coarse wavelength division multiplexers (WDMs). The totally passive scheme has the advantages of high operation frequency and loose requirements for the working environment. An acceleration...
A novel optical fiber Fabry-Perot filter (FFPF) based on two microlenses is proposed and demonstrated. The microlens is produced by forming a droplet with UV-curing adhesive on the mirror of the filter. An FFPF with a finesse of 65 was obtained in the experiment. The advantages of the high-finesse FFPF are the low cost and ease of construction. © 2...
A novel white-light interferometry capable of retrieving the absolute optical path difference is presented, in which a 3x3 coupler-based interferometer is employed. The measured phase change is in agreement with that obtained by Fourier transform white-light interferometry. The linear property is also experimentally demonstrated.
Micro-lenses are produced on two mirror-coated fiber ends in an extrinsic Fabry–Perot interferometer (EFPI) by curing epoxy droplets to obtain a high-finesse resonator. The high-finesse resonator is easy to construct, and can be used as a highly sensitive sensor at a low cost. The experimental results show that a temperature resolution of 0.025 °C...
An optical fiber methane sensing system utilizing a super-luminescent diode (SLD) in the 1.33-μm band and a fiber Fabry–Perot tunable filter (FFP-TF) is developed. A two-step reference measuring method, which is based on differential absorption technique, is employed; a reference channel is introduced to eliminate the fluctuation of the illuminant...
An improved peak-to-peak method is developed for interrogating the absolute cavity length of fiber optic extrinsic Fabry-Perot interferometric (EFPI) sensors with high resolution. A fiber Fabry-Perot tunable filter (FFP-TF) is used to scan the optical spectrum of an EFPI, and the problems caused by the nonlinear performance and poor repeatability o...
A four-element hydrophone array system using a fiber Bragg grating laser system is described. The demodulation technique for the array combines a 3x3 coupler-based interferometer and three wavelength division multiplexers (WDMs). It is believed to be a new passive approach to use a WDM and a unique arithmetic method. The operational frequency limit...