Shifted Fiber

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Prem Kumar - One of the best experts on this subject based on the ideXlab platform.

Qi Wu - One of the best experts on this subject based on the ideXlab platform.

  • $\pi$ -Phase-Shifted Fiber Bragg Grating for Strain Measurement With High Spatial Resolution
    IEEE Photonics Technology Letters, 2019
    Co-Authors: Hongzhou Zhai, Qi Wu, Ke Xiong, Rong Wang
    Abstract:

    Because the static strain measured by a uniform Fiber Bragg grating is a mean value along the grating length, it is difficult to precisely measure a local strain when encountering nonuniformity. It is found that phase-Shifted Fiber Bragg gratings have short effective grating length and reflectivity approaching one at the central peak; these properties are beneficial for improving the spatial resolution. These advantages have been validated by calculating the light power distribution along the grating and by spectrum simulation using the transfer-matrix method integrated with finite element simulation. An interrogation system integrated with a newly designed algorithm has been used to automatically track the wavelength shift in the central peak. A set of comparison experiments that mimicked symmetrically parabolic strain and linearly increasing strain were conducted to demonstrate the advantage of the phase-Shifted Fiber Bragg grating over the conventional Fiber Bragg grating in static measurements.

  • Application of phase Shifted Fiber Bragg grating to advanced ultrasonic structural health monitoring
    Asia Pacific Optical Sensors Conference, 2016
    Co-Authors: Qi Wu, Fengming Yu, Yoji Okabe, Wensheng Kong
    Abstract:

    Several novel sensing systems based on phase-Shifted Fiber Bragg grating with high sensitivity and broad bandwidth were proposed and applied to acoustic emission detection and nonlinear ultrasonic detection, demonstrating their abilities in practical applications.

  • novel real time acousto ultrasonic sensors using two phase Shifted Fiber bragg gratings
    Journal of Intelligent Material Systems and Structures, 2014
    Co-Authors: Qi Wu, Yoji Okabe
    Abstract:

    A novel real-time acousto-ultrasonic sensor system using a phase-Shifted Fiber Bragg grating rather than a normal Fiber Bragg grating was investigated. The spectrum of the phase-Shifted Fiber Bragg grating was simulated and analyzed, which indicates that a phase-Shifted Fiber Bragg grating has superior properties when compared to a normal Fiber Bragg grating. Based on theoretical considerations, a novel real-time acousto-ultrasonic sensor system was proposed. Two identical 5-mm phase-Shifted Fiber Bragg gratings, with slightly different Bragg wavelengths, were used as the filter and the sensor. An amplified spontaneous emission light source and an apodized Fiber Bragg grating were connected to illuminate the phase-Shifted Fiber Bragg gratings. The design allows the strain resulting from the ultrasonic wave to be precisely received and converted to the fluctuation of the output voltage. An ultrasonic wave generated in a carbon Fiber–reinforced plastic plate using a macroFiber composite actuator was detecte...

  • Ultrasensitive Optical-Fiber Ultrasonic Sensor Based on Phase-Shifted Fiber Bragg Gratings
    Structural Health Monitoring 2013 Vols 1 and 2, 2013
    Co-Authors: Qi Wu, Fengming Yu, Yoji Okabe, Kazuya Saito
    Abstract:

    Using optical method in structural health monitoring (SHM) is getting more and more attentions recently due to the inherent advantages in Fiber optical method. In this research, we proposed an ultrasonic phase-Shifted Fiber Bragg grating (PS-FBG) sensor and demonstrated its application to ultrasonic SHM. Based on this sensor, two different demodulation systems were developed, named as cascaded PS-FBG sensing system and PS-FBG balanced sensing system, for acousto-ultrasonic detection and acoustic emission detection. The experimental results show that PS-FBG sensor with higher sensitivity compared to other existent FBG has a potential to replace traditional ultrasonic lead-zirconate-titanate sensors.

  • high sensitivity ultrasonic phase Shifted Fiber bragg grating balanced sensing system
    Optics Express, 2012
    Co-Authors: Qi Wu, Yoji Okabe
    Abstract:

    A high-sensitivity ultrasonic sensing system is proposed and demonstrated. In this system, a phase-Shifted Fiber Bragg grating (PS-FBG) is used as a sensor to achieve broadband and highly sensitive detection. The PS-FBG modulates the output of a tunable laser to detect the ultrasonic strain directly. Balanced photo-detector (BPD) is used for eliminating the DC component and further amplifying the AC component in the detected signal. Another major function of the BPD is to reject laser intensity noise. As a result, the minimum detectable strain is limited by the BPD’s noise and laser frequency noise. The sensitivity of the system is 9 ne/Hz1/2. Because of its high sensitivity, this system has the potential to be used in acousto-ultrasonic testing without amplifying the input signal and in practical acoustic emission detection.

Jun Chen - One of the best experts on this subject based on the ideXlab platform.

Gang-ding Peng - One of the best experts on this subject based on the ideXlab platform.

  • Study of a single longitudinal Fiber ring laser with a π phase-Shifted Fiber Bragg grating
    Optics Communications, 2017
    Co-Authors: Weitao Wang, Zhiqiang Song, Haifeng Qi, Xiaolei Zhang, Jiasheng Ni, Chang Wang, Gang-ding Peng
    Abstract:

    Abstract A single-longitudinal-mode Fiber laser is presented, which is composed of a ring cavity laser and a π phase-Shifted Fiber Bragg grating. The ring cavity structure can reduce the spatial hole burning, but the mode hopping and competition are still existing due to the long Fiber ring cavity length. The π phase-Shifted Fiber Bragg grating has very narrow transmittance spectrum width as a band-pass filter. Combined with a wavelength-matching Fiber Bragg grating, it is able to efficiently suppress the mode hopping and competition in the ring cavity. The single longitudinal mode lasing is verified using a scanning F-P interferometer. Its frequency noise is measured by the self-homodyne technology with a 3×3 optical Fiber coupler. The calculated linewidth from the frequency noise is about 21 kHz when the measurement time is 0.2 s.

  • Polarization-Dependent Phase-Shifted Fiber Bragg Gratings Inscribed by Femtosecond Laser Overexposure
    2016 Asia Communications and Photonics Conference (ACP), 2016
    Co-Authors: Jun He, Yiping Wang, Changrui Liao, Ying Wang, Kai Ming Yang, Gang-ding Peng
    Abstract:

    Polarization dependent phase-Shifted Fiber Bragg gratings (PS-FBGs) were fabricated with 800 nm femtosecond laser overexposure and a uniform phase mask. Negative index change created in the center was responsible for the PS-FBG formation.

  • performance enhancement of vibration sensing employing multiple phase Shifted Fiber bragg grating
    Journal of Lightwave Technology, 2011
    Co-Authors: Asrul Izam Azmi, Wenjuan Sheng, John Canning, Gang-ding Peng
    Abstract:

    Multiple phase-Shifted Fiber Bragg gratings (MPS-FBGs) are proposed for a novel intensity-type vibration sensing scheme with broadband source based interrogation. In this scheme, the collective and simultaneous operation of the subchannels of MPS-FBG multiplies the total acquired signal power change at a particular channel, considerably enhancing sensitivity. Compared to a standard FBG scheme, our experiment scheme attained significant sensitivity enhancement of nearly 20 dB using 17 phase-Shifted FBG. These experimental results agree with the theoretical prediction based on cross-correlation relations. The sensitivity enhancement while retaining the system simplicity would be an attractive option for an economical coarse wavelength division multiplexed (CWDM) vibration sensing system based on a single broadband source.

Yoji Okabe - One of the best experts on this subject based on the ideXlab platform.

  • Application of phase Shifted Fiber Bragg grating to advanced ultrasonic structural health monitoring
    Asia Pacific Optical Sensors Conference, 2016
    Co-Authors: Qi Wu, Fengming Yu, Yoji Okabe, Wensheng Kong
    Abstract:

    Several novel sensing systems based on phase-Shifted Fiber Bragg grating with high sensitivity and broad bandwidth were proposed and applied to acoustic emission detection and nonlinear ultrasonic detection, demonstrating their abilities in practical applications.

  • novel real time acousto ultrasonic sensors using two phase Shifted Fiber bragg gratings
    Journal of Intelligent Material Systems and Structures, 2014
    Co-Authors: Qi Wu, Yoji Okabe
    Abstract:

    A novel real-time acousto-ultrasonic sensor system using a phase-Shifted Fiber Bragg grating rather than a normal Fiber Bragg grating was investigated. The spectrum of the phase-Shifted Fiber Bragg grating was simulated and analyzed, which indicates that a phase-Shifted Fiber Bragg grating has superior properties when compared to a normal Fiber Bragg grating. Based on theoretical considerations, a novel real-time acousto-ultrasonic sensor system was proposed. Two identical 5-mm phase-Shifted Fiber Bragg gratings, with slightly different Bragg wavelengths, were used as the filter and the sensor. An amplified spontaneous emission light source and an apodized Fiber Bragg grating were connected to illuminate the phase-Shifted Fiber Bragg gratings. The design allows the strain resulting from the ultrasonic wave to be precisely received and converted to the fluctuation of the output voltage. An ultrasonic wave generated in a carbon Fiber–reinforced plastic plate using a macroFiber composite actuator was detecte...

  • Ultrasensitive Optical-Fiber Ultrasonic Sensor Based on Phase-Shifted Fiber Bragg Gratings
    Structural Health Monitoring 2013 Vols 1 and 2, 2013
    Co-Authors: Qi Wu, Fengming Yu, Yoji Okabe, Kazuya Saito
    Abstract:

    Using optical method in structural health monitoring (SHM) is getting more and more attentions recently due to the inherent advantages in Fiber optical method. In this research, we proposed an ultrasonic phase-Shifted Fiber Bragg grating (PS-FBG) sensor and demonstrated its application to ultrasonic SHM. Based on this sensor, two different demodulation systems were developed, named as cascaded PS-FBG sensing system and PS-FBG balanced sensing system, for acousto-ultrasonic detection and acoustic emission detection. The experimental results show that PS-FBG sensor with higher sensitivity compared to other existent FBG has a potential to replace traditional ultrasonic lead-zirconate-titanate sensors.

  • high sensitivity ultrasonic phase Shifted Fiber bragg grating balanced sensing system
    Optics Express, 2012
    Co-Authors: Qi Wu, Yoji Okabe
    Abstract:

    A high-sensitivity ultrasonic sensing system is proposed and demonstrated. In this system, a phase-Shifted Fiber Bragg grating (PS-FBG) is used as a sensor to achieve broadband and highly sensitive detection. The PS-FBG modulates the output of a tunable laser to detect the ultrasonic strain directly. Balanced photo-detector (BPD) is used for eliminating the DC component and further amplifying the AC component in the detected signal. Another major function of the BPD is to reject laser intensity noise. As a result, the minimum detectable strain is limited by the BPD’s noise and laser frequency noise. The sensitivity of the system is 9 ne/Hz1/2. Because of its high sensitivity, this system has the potential to be used in acousto-ultrasonic testing without amplifying the input signal and in practical acoustic emission detection.

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