Junfeng Jiang

Tianjin University, T’ien-ching-shih, Tianjin Shi, China

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Publications (42)43.75 Total impact

  • 04/2014; 26(10).
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    ABSTRACT: We present a high precision and fast speed demodulation method for a polarized low-coherence interferometer with location-dependent birefringence dispersion. Based on the characteristics of location-dependent birefringence dispersion and five-step phase-shifting technology, the method accurately retrieves the peak position of zero-fringe at the central wavelength, which avoids the fringe order ambiguity. The method processes data only in the spatial domain and reduces the computational load greatly. We successfully demonstrated the effectiveness of the proposed method in an optical fiber Fabry-Perot barometric pressure sensing experiment system. Measurement precision of 0.091 kPa was realized in the pressure range of 160 kPa, and computation time was improved by 10 times compared to the traditional phase-based method that requires Fourier transform operation.
    Optics Letters 04/2014; 39(7):1827-30. · 3.39 Impact Factor
  • Mali Zhao, Tiegen Liu, Junfeng Jiang, Meng Wang
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    ABSTRACT: Defocusing distance plays a key role in laser cleaning result and can be either positive or negative, depending on the focus position relative to the sample surface. In this paper, we investigate the effect of the defocusing distance on the cleaning efficiency of oxidized brass surface. The oxide layer from the surface of a brass ring was processed with a three dimensional (3-D) dynamically focused laser galvanometer scanning system. The relationship between removal efficiency of the oxide layer and the defocusing distance was analyzed. The sample surface topography, element content before and after the laser cleaning were analyzed by a scanning electron microscope (SEM) and Energy-dispersive X-ray spectroscopy (EDS), the surface quality after laser cleaning was analyzed by a Atomic Force Microscope (AFM), the chemical constituents of the oxide layer on the sample surface after being processed with different defocusing distances were examined by x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The results show that the ratios of Cu/O and Zn/O reach the maximum of 53.2 and 27.78 respectively when the defocusing distance is +0.5 mm. The laser pulses will lose the ability to remove the oxide layer from the substrate surface when the defocusing distance is larger than ±2 mm.
    Optics and Lasers in Engineering 01/2014; 59:11–18. · 1.92 Impact Factor
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    ABSTRACT: We propose and simulate an on-chip mid-IR frequency comb generator based on the four-wave mixing (FWM) effect in a coupled silicon microring resonator. The resonator is formed by suspended ridge waveguides that are designed to have low group-velocity dispersion. A continuous-wave pump laser coupled into the resonator excites other longitudinal modes of the resonator through FWM-based parametric oscillations. In comparison with the device based on a single-ring resonator, we numerically demonstrate that the pump threshold can be dramatically reduced by introducing an auxiliary ring resonator to compensate the phase mismatch between the pump and the generated comb components. The proposed frequency comb generator has a low pump threshold of ~40 mW and a high efficiency of ~25% at the pump power of 100 mW.
    Optics Communications 01/2014; 332:125–131. · 1.44 Impact Factor
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    ABSTRACT: We investigated the fiber Bragg grating (FBG) thermal response in space vacuum thermal environment. The FBGs were packaged with 6061-T6 aluminum. The liquid nitrogen immersion experiment results show that its wavelength shift standard deviation is 0.76 pm for 217 h. The combination effect of vacuum and cryogenic temperature was studied by thermal cycling process in space environment simulator. The FBG sensors show accuracy better than 2% full scale, and the hysteresis errors are below 1%. It proves that these metal packaged FBG sensors can survive and meet the requirement of space measurement.
    The Review of scientific instruments 12/2013; 84(12):123107. · 1.52 Impact Factor
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    ABSTRACT: We present an effective method to compensate the spatial-frequency nonlinearity for polarized low-coherence interferometer with location-dependent dispersion element. Through the use of location-dependent dispersive characteristics, the method establishes the exact relationship between wave number and discrete Fourier transform (DFT) serial number. The jump errors in traditional absolute phase algorithm are also avoided with nonlinearity compensation. We carried out experiments with an optical fiber Fabry-Perot (F-P) pressure sensing system to verify the effectiveness. The demodulated error is less than 0.139kPa in the range of 170kPa when using our nonlinearity compensation process in the demodulation.
    11/2013;
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    ABSTRACT: We fabricated MEMS-based optical fiber pressure sensor with anodic bonding. The vacuum-sealed microcavity with a thin silicon diaphragm is used as sensing element and its deformation characteristics determine the pressure measurement performance. Considering residual gas inside Fabry-Perot cavity and the thermal properties of material, we established a sensor's temperature response mathematical model based on ideal gas equation and elastic theory. Temperature experiment of this sensor was carried out under vacuum. This work will provide a guide of temperature compensation process for achieving high precision pressure measurement.
    11/2013;
  • Xuezhi Zhang, Tiegen Liu, Junfeng Jiang, Kun Liu
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    ABSTRACT: A demodulation algorithm for Low-coherence Interferometry is proposed. The demodulation includes a Lithium Niobate wedge, which index is tunable via optics-electric property. This method is based on the theorem that second harmonic term is orthogonal with the fundamental term in Fourier transform. An alternative external electric field is imposed on the wedge and tune the position of Low-coherence Interferometry is proposed. For every point on the CCD camera, the variation of the detected light power is Fourier transformed and obtains the ratio between second-harmonic term and fundamental term. This paper demonstrate theoretically that proposed demodulation method can enhance the accuracy of pressure sensing for more than 35 times.
    11/2013;
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    ABSTRACT: Optical fiber sensor has great advantage for applications dealing with extreme environment. We developed a high precision optical pressure sensor for aviation industry. The optical pressure sensor is based on two-beam interference of microcavity and is fabricated with Micro-electromechanical systems (MEMS) and laser fusion technology. The cavity length variation resulting from external pressure is demodulated with spatial polarization low coherence interference unit and a high stable phase demodulation algorithm. The effect of light source output parameter is also investigated. We carried out research on optical fiber strain, temperature and acoustic vibration sensor for aerospace application. The optical fiber sensors for strain and temperature measurement are based on fiber Bragg grating(FBG).Both bare FBG and packaged FBG performances under cryogenic temperature and high vacuum are investigated. An eight-channel parallel FBG wavelength interrogator is developed. The optical fiber acoustic vibration sensor is based on two-beam interference of microcavity and use intensity demodulation method for high speed response. The mutiple-parameter and multiplepoint measurement instrument is successfully applied to status monitoring of water sublimator.
    11/2013;
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    ABSTRACT: A simple photonic approach to generate ultrawideband (UWB) pulse signals utilizing a gain-switched semiconductor laser with optical feedback is proposed and demonstrated. The RF spectrum of the generated chaotic UWB signals has a -10 dB bandwidth of 9 GHz and central frequency of 6.6 GHz (fractional bandwidth of 155%), which is consistent with the Federal Communications Commission indoor mask. The central frequency and -10 dB bandwidth can be tuned by adjusting the bias current and feedback strength of the semiconductor laser. After transmission through a 30 km single-mode fiber, the spectrum shape of the chaotic UWB signals is almost unaffected by the chromatic dispersion of the fiber.
    Applied Optics 11/2013; 52(31):7512-6. · 1.69 Impact Factor
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    ABSTRACT: We propose a new wavelength-division-multiplexing method for extrinsic fiber Fabry-Perot interferometric (EFPI) sensing in a polarized low-coherence interferometer configuration. In the proposed method, multiple LED sources are used with different center wavelengths, and each LED is used by a specific sensing channel, and therefore the spatial frequency of the low-coherence interferogram of each channel can be separated. A bandpass filter is used to extract the low-coherence interferogram of each EFPI channel, and thus the cavity length of each EFPI channel can be identified through demultiplexing. We successfully demonstrate the simultaneous demodulation of EFPI sensors with same nominal cavity length while maintaining high measurement precision.
    Optics Letters 10/2013; 38(19):3751-3753. · 3.39 Impact Factor
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    ABSTRACT: A demodulation algorithm based on the birefringence dispersion characteristics for a polarized low-coherence interferometer is proposed. With the birefringence dispersion parameter taken into account, the mathematical model of the polarized low-coherence interference fringes is established and used to extract phase shift information between the measured coherence envelope center and the zero-order fringe, which eliminates the interferometric 2π ambiguity of locating the zero-order fringe. A pressure measurement experiment using an optical fiber Fabry-Perot pressure sensor was carried out to verify the effectiveness of the proposed algorithm. The experiment result showed that the demodulation precision was 0.077 kPa in the range of 210 kPa, which was improved by 23 times compared to the traditional envelope detection method.
    Optics Letters 08/2013; 38(16):3169-3172. · 3.39 Impact Factor
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    ABSTRACT: A chaotic ultra-wideband (UWB) over fiber link based on optical feedback laser diode which generates the chaotic laser signals is proposed and demonstrated. Flexible generation of up to 1.44 Gb/s on-off keying chaotic-UWB signals is successfully achieved. Without utilizing any dispersion compensation module, the signals with bit rate of 1.44 Gb/s were detected using a digital signal processing receiver after 20-km optical fiber and 0.6-m wireless channel transmission. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1504–1507, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27615
    Microwave and Optical Technology Letters 07/2013; 55(7). · 0.59 Impact Factor
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    ABSTRACT: We present a simple and effective method to compensate the optical frequency tuning nonlinearity of a tunable laser source (TLS) in a long range optical frequency-domain reflectometry (OFDR) by using the deskew filter, where a frequency tuning nonlinear phase obtained from an auxiliary interferometer is used to compensate the nonlinearity effect on the beating signals generated from a main OFDR interferometer. The method can be applied to the entire spatial domain of the OFDR signals at once with a high computational efficiency. With our proposed method we experimentally demonstrated a factor of 93 times improvement in spatial resolution by comparing the results of an OFDR system with and without nonlinearity compensation. In particular we achieved a measurement range of 80 km and a spatial resolution of 20 cm and 1.6 m at distances of 10 km and 80 km, respectively with a short signal processing time of less than 1 s for 5 × 10<sup>6</sup> data points. The improved performance of the OFDR with a high spatial resolution, a long measurement range and a short process time will lead to practical applications in the real-time monitoring, test and measurement of fiber optical communication networks and sensing systems.
    Optics Express 02/2013; 21(3):3826-3834. · 3.55 Impact Factor
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    ABSTRACT: We proposed an improved polarization control method to reduce polarization-induced phase shift (PIPS) and polarization-induced fading (PIF) in a dual Mach-Zehnder interferometry (DMZI) disturbance sensing system. PIPS and PIF will seriously affect the positioning accuracy of the DMZI sensor. This polarization control method uses two PCs to control the state of polarization at the inputs of clockwise Mach-Zehnder interferometer and counter-clockwise Mach-Zehnder interferometer, respectively, based on chaotic particle swarm optimization algorithm, which has advantages of high speed and easy implementation. We experimentally demonstrated that the polarization method can overcome the effect of PIPS and PIF, improve the positioning accuracy of the DMZI sensor efficiently with positioning error of ±20 m after polarization control. Compared with the traditional polarization control method in DMZI based on the criterion of visibility, the positioning error of the sensor using our proposed method has been reduced at least an order of magnitude.
    Journal of Lightwave Technology 01/2013; 31(19):3135-3141. · 2.56 Impact Factor
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    ABSTRACT: We present a novel method to significantly extend the measurement range of an optical frequency domain reflectometry (OFDR) beyond the laser coherence length for both discrete reflection (such as Fresnel reflection) and Rayleigh backscattering measurements. A key to the method is to increase the laser frequency tuning speed while measuring the phase noise of the reflected optical signal that carries the location and reflectivity information. Using this technique in a conventional OFDR with a noise floor of -120 dB and a dynamic range of 53 dB, we achieved a measurable distance of 170 km for Fresnel reflection and 120 km for Rayleigh backscattering using a laser with a coherence length of only 13.6 km.
    IEEE Photonics Technology Letters 01/2013; 25(2):202-205. · 2.04 Impact Factor
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    ABSTRACT: A simple and effective method for polarized low-coherence interference is proposed in this letter. Despite the need to extract the coherence envelope, it sets an appropriate threshold to retrieve valid peaks or troughs from various fluctuations. Subsequently, we can utilize any valid peak or trough for demodulation. Experiments were carried out to demonstrate the validity and exceptionally good performance of this method. Experimental results have shown that the proposed method can achieve higher accuracy and stability when compared with the envelope peak detection method.
    IEEE Photonics Technology Letters 08/2012; 24(16):1390-1392. · 2.04 Impact Factor
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    ABSTRACT: A demodulation algorithm based on absolute phase recovery of a selected monochromatic frequency is proposed for optical fiber Fabry-Perot pressure sensing system. The algorithm uses Fourier transform to get the relative phase and intercept of the unwrapped phase-frequency linear fit curve to identify its interference-order, which are then used to recover the absolute phase. A simplified mathematical model of the polarized low-coherence interference fringes was established to illustrate the principle of the proposed algorithm. Phase unwrapping and the selection of monochromatic frequency were discussed in detail. Pressure measurement experiment was carried out to verify the effectiveness of the proposed algorithm. Results showed that the demodulation precision by our algorithm could reach up to 0.15kPa, which has been improved by 13 times comparing with phase slope based algorithm.
    Optics Express 07/2012; 20(16):18117-26. · 3.55 Impact Factor
  • Junfeng Jiang, Tiegen Liu, Kun Liu, Yimo Zhang
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    ABSTRACT: A simple equation for peak wavelength detection of fiber Bragg grating (FBG) with three spectral data is proposed, which has almost the same order of computing load as the conventional maximum search algorithm and uncertainty as the least-squares fit algorithm. The factors effecting performance of the new technique was investigated by simulation. For FBG with spectral bandwidth 0.2 nm, simulation results show that sample resolution lying between 0.07 and 0.16 nm have small measure standard deviation, which is less than 1 pm for SNR greater than 20.75 dB. Experiments were carried out with FBG and interrogator based on InGaAs linear array, and the results verified the effectiveness of the new technique.
    Optical Engineering 03/2012; 51(3):4403-. · 0.88 Impact Factor
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    ABSTRACT: Detection of pollution, inflammable, explosive gases such as methane, acetylene, carbon monoxide and so on is very important for many areas, such as environmental, mining and petrochemical industry. Intra-cavity gas absorption sensing technique (ICGAST) based on Erbium-doped fiber ring laser (EDFRL) is one of novel methods for trace gas with higher precision. It has attracted considerable attention, and many research institutes focus on it. Instrumentation and optimization of ICGAST was reported in this paper. The system consists of five parts, which are variable gain module, intelligent frequency-selection module, gas cell, DAQ module and computer respectively. Variable gain module and intelligent frequency-selection module are combined to establish the intra-cavity of the ring laser. Gas cell is used as gas sensor. DAQ module is used to realize data acquisition synchronously. And gas demodulation is finished in the computer finally. The system was optimized by adjusting the sequence of the components. Take experimental simulation as an example, the absorptance of gas was increased five times after optimization, and the sensitivity enhancement factor can reach more than twenty. By using Fabry-Perot (F-P) etalon, the absorption wavelength of the detected gas can be obtained, with error less than 20 pm. The spectra of the detected gas can be swept continuously to obtain several absorption lines in one loop. The coefficient of variation (CV) was used to show the repeatability of gas concentration detection. And results of CV value can be less than 0.014.
    Proc SPIE 11/2011;