scholarly journals Ultrashort Long-Period Fiber Gratings Inscribed on a Single-Mode Fiber for Torsion Sensing Applications

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Marta Nespereira ◽  
João M. P. Coelho ◽  
José Manuel Rebordão
Keyword(s):  
Single Mode ◽  
Single Mode Fiber ◽  
Wavelength Shift ◽  
Fiber Grating ◽  
Long Period ◽  
Sensing Applications ◽  
High Tension ◽  
Long Period Fiber Gratings ◽  
Order Of Magnitude ◽  
Period Fiber Grating

The response of ultrashort-length CO2-induced long-period fiber grating (LPFG) sensors to torsion is reported. While engraving using CO2 laser radiation, the fiber is submitted to high tension allowing the obtainment of gratings with shorter lengths, down to 2.4 mm, which is almost one order of magnitude lower than the usual. Also, the fiber is only irradiated in one side, creating an asymmetrical profile leading to highly birefringent gratings. Sensitivity to axial twists is demonstrated, with values up to 0.15 nm/(rad/m) for the resonant wavelength shift and higher than 0.03 dBm/(rad/m) for the variation in the intensity (attenuation). Discrimination between rotation directions, clockwise and counterclockwise, was observed.

scholarly journals Helically twisted long-period fiber gratings of YOFC single-mode fiber with optical fiber welding machine

2021 ◽  
Vol 51 (3) ◽  
Author(s):  
Yunfeng Bai ◽  
Zelong He ◽  
Jiyuan Bai ◽  
Suihu Dang
Keyword(s):  
Single Mode ◽  
Resonance Wavelength ◽  
Single Mode Fiber ◽  
Resonant Peak ◽  
Fiber Grating ◽  
Fiber Gratings ◽  
Long Period ◽  
Welding Machine ◽  
Long Period Fiber Gratings ◽  
Period Fiber Grating

The single-mode fiber provided by YOFC inc is employed for spiral processing by commercial welding machine. It can clearly see the periods structure under the light, but there is no obvious deformation of the fiber core, cladding and surface morphology under a microscope. There is an obvious resonant peak near 1560 nm, half peak width is about 25 nm, the depth of the resonant peak closed to –26 dB, when the period is about 411 μm. It agrees with theoretical calculation results according to the long-period fiber grating coupled-mode theory. The resonance wavelength is caused by coupling between the fundamental mode and the LP14 mode. The responsivities of the helically twisted long-period fiber gratings (H-LPFG) for the temperature is measured, the resonance wavelength is linear with temperature, the slope is 86 pm/℃. Because it is easy to inscribe by commercial welding machine, and has a strong resonance peak, it has potential applications as the temperature sensor.

scholarly journals Ultrashort Long-Period Fiber Grating Sensors Inscribed on a Single Mode Fiber Using CO2 Laser Radiation

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Marta Nespereira ◽  
João M. P. Coelho ◽  
Manuel Abreu ◽  
José Manuel Rebordão
Keyword(s):  
Laser Radiation ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Fiber Grating ◽  
Fiber Gratings ◽  
Long Period Fiber Grating ◽  
Long Period ◽  
Long Period Fiber Gratings ◽  
Co2 Laser Radiation ◽  
Period Fiber Grating

Sensing performances of ultrashort (as low as 2.4 mm) long-period fiber gratings fabricated with CO2 laser radiation using commercial single mode fibers are presented. These lengths are, to our knowledge, the shortest of those found in the literature for this kind of sensors, approaching those typical in fiber Bragg gratings. Sensitivity to temperature and refractive index are demonstrated, with performances within the range expected for a single LPFG written on a single mode fiber without any enhancing technique. Analysis on results is made based on both theoretical and experimental data.

Resin Made Long-Period Fiber Grating Structure for Tunable Optical Filter inside Single-Mode Fiber

2020 ◽  
Vol 861 ◽  
pp. 259-263
Author(s):  
Ravivudh Khun-In ◽  
Yuji Usuda ◽  
Yuttapong Jiraraksopakun ◽  
Apichai Bhatranand ◽  
Hideki Yokoi
Keyword(s):  
Optical Filter ◽  
Single Mode ◽  
Grating Period ◽  
Single Mode Fiber ◽  
Fiber Axis ◽  
Wavelength Shift ◽  
Fiber Grating ◽  
Long Period Fiber Grating ◽  
Long Period ◽  
Period Fiber Grating

The rectangular-structured resin with one of its triangular long-period fiber grating surface is designed and printed out by using a high resolution 3D printer, so called long-period fiber grating (LPFG) resin. This LPFG resin is directly pressed on the bare single-mode fiber by a digital force meter to filter out partial band of light inside the fiber. The grating period is expanded by tilting the resin from the initial fiber axis. The optical filter is observed as resonant wavelengths from the broadband wavelength. The results show that the resonant wavelength shift is a linear function of the grating period with the coefficient of determination over 0.99. The proposed scheme has a great potential to be employed as a sensor such as a selective optical filter and a buried intrusion sensor.

scholarly journals Sensing and Demodulation of Special Long-Period Fiber Gratings Induced by ScanningCO2Laser Pulses

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Tao Zhu ◽  
Leilei Shi ◽  
Min Liu ◽  
Wei Huang
Keyword(s):  
Single Mode ◽  
Laser Pulses ◽  
Single Mode Fiber ◽  
Wavelength Shift ◽  
Refractive Index Sensor ◽  
Fiber Gratings ◽  
Long Period ◽  
Investigation Methods ◽  
Long Period Fiber Gratings ◽  
Sensor Strain

A review of long-period fiber gratings (LPFGs) with special structures induced by scanning CO2laser pulses in single mode fiber (SMF) is presented in this paper. In the first part, the special structures and fabrication methods of LPFGs are demonstrated in detail. Next, the special LPFG-based sensors are demonstrated, such as refractive index sensor, strain sensor with temperature compensation, and torsion sensor without temperature crosstalking. Finally, several investigation methods including intensity, wavelength shift, and fiber ring laser demodulation are discussed.

scholarly journals Transverse Load and Temperature Sensing Using Multiplexed Long-Period Fiber Gratings

Photonics ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 1
Author(s):  
Ismael Torres-Gómez ◽  
Alejandro Martínez-Rios ◽  
Gilberto Anzueto-Sánchez ◽  
Daniel. E. Ceballos-Herrera ◽  
Guillermo Salceda-Delgado
Keyword(s):  
Simultaneous Measurement ◽  
Room Temperature ◽  
Transverse Load ◽  
Fiber Grating ◽  
Fiber Gratings ◽  
Long Period Fiber Grating ◽  
Long Period ◽  
Sensing Applications ◽  
Long Period Fiber Gratings ◽  
Period Fiber Grating

The simultaneous measurement of transverse load and temperature using two long-period fiber gratings multiplexed in the wavelength domain is presented experimentally. For this, a mechanically induced long-period fiber grating (MI-LPFG) and a long-period fiber grating inscribed by a continuous-wave CO2 laser (CO2 LPFG) are connected in cascade. First, the transverse load and the temperature measurements were individually performed by the multiplexed long-period fiber gratings configuration. The MI-LPFG is subject to a transverse load variation from 0–2000 g with steps of 500 g, whereas the CO2 LPFG is unloaded and they are kept at room temperature. Similarly, the CO2 LPFG is subject to a temperature variation from 30 to 110 °C by increments of 20 °C, while the MI-LPFG with a constant transverse load of 2000 g is kept at room temperature. Subsequently, the simultaneous measurement of the transverse load and the temperature is performed by the multiplexed long-period fiber grating following the steps outlined above. According to the experimental results, the transverse load and temperature measurement present high repeatability for the individual and simultaneous process. Moreover, the multiplexed LPFGs exhibit low cladding-mode crosstalk of transverse load and temperature. The coarse wavelength-division multiplexing (CWDM) of long-period fiber gratings is an attractive alternative technique in optical fiber distributed sensing applications.

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