We propose a real-time multi-monitoring interrogation technique based on Fourier domain mode-locked fiber laser for simultaneous measurement of radiation dose and multi-point strain. Radiation dose and multipoint strain can be monitored in real-time by measuring the variation of output power and detection time interval of the sensing signals. Since the operating wavelength of the FDML is continuously controlled as a function of time, it is possible to simultaneously measure the variation of radiation dose and multipoint strain in real time.
We propose a sensing scheme of an erbium-doped fiber (EDF) ring laser for multi-monitoring of radiation dose and strain simultaneously. The EDF and fiber Bragg grating (FBG) are exploited as sensing probes for simultaneous measurement of radiation dose and strain. The output power and the lasing wavelength of the proposed EDF laser are changed by increasing the radiation dose and strain, respectively. The radiation and strain sensitivities were measured to be 8.4 dB/km∙Gy and 0.81 pm/με, respectively.
We propose a sensing scheme of an erbium-doped fiber (EDF) ring laser for multi-monitoring of radiation dose and
strain simultaneously. The EDF and fiber Bragg grating (FBG) are exploited as sensing probes for simultaneous
measurement of radiation dose and strain. The output power and the lasing wavelength of the proposed EDF laser are
changed by increasing the radiation dose and strain, respectively. The radiation and strain sensitivities were measured to
be 8.4 dB/km•Gy and 0.81 pm/με, respectively.
A simple scheme for simultaneous measurement of bending and temperature based on a dualwavelength Raman
fiber laser at a long distance of more than 50 km is investigated without additional light sources.
A hybrid Sagnac interferometer with a D-shaped polarization maintaining fiber (PMF) and a fiber Bragg grating (FBG)
is proposed and experimentally demonstrated for simultaneous measurement of ambient index and temperature. Since
the core mode of the locally D-shaped PMF is directly interfaced to the external environment, the interference pattern of
the D-shaped-PMF-based Sagnac interferometer is immediately changed by the variation of external index and
temperature. The resonant wavelength of the FBG, however, responds only to the temperature change. Therefore, it is
possible to discriminate ambient index and temperature sensitivities by using the proposed hybrid Sagnac interferometer.
A simple and flexible sensing configuration for discrimination of temperature and strain is investigated by implementing
a PM-PCF-based Sagnac fiber loop mirror incorporating an EDF. The integration of an optical source and the sensing
probe can obviously simplify the overall system configuration without requiring any additional broadband light source.
Since the ASE of the EDF was reduced by the increase of temperature, the transmission peak power of the proposed
sensor decreased as the temperature increased. The temperature sensitivity of the transmission peak power was estimated
to be -0.04 dB/°C. When the strain was applied to the proposed sensing head, the transmission peak power was not
changed by the applied strain because the ASE power of the EDF was independent of the strain. However, the peak
wavelength shifted into the longer wavelength because the variation of the peak wavelength was directly proportional to
the applied strain. The strain sensitivity was measured to be 1.3 pm/με
A Sagnac loop interferometer based on a hybrid polarization maintaining fiber (PMF) is proposed and experimentally
demonstrated for measurement of ambient index. The hybrid PMF consists of the PMF and the locally D-shaped PMF.
The important key component is the locally D-shaped PMF. Since the core mode of the locally D-shaped PMF is directly
interfaced to the external environment, the core mode is immediately changed by the variation of external index. The
birefringence of the locally D-shaped PMF can generate the interference patterns. Consequently, the flexibility and
simplicity in the sensing scheme can be provided by the ambient index change can be measured simply and flexibly
since the peak wavelength shift is only monitored by changing the ambient index. The sensitivity of ambient index was
measured to be -30 nm/RIU.
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