scholarly journals Sensing Characteristics of Tilted Long Period Fiber Gratings Inscribed by Infrared Femtosecond Laser

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3003 ◽  
Author(s):  
Jian Tang ◽  
Cailing Fu ◽  
Zhiyong Bai ◽  
Changrui Liao ◽  
Yiping Wang
Keyword(s):  
Refractive Index ◽  
Fiber Grating ◽  
Fiber Gratings ◽  
Long Period Fiber Grating ◽  
Long Period ◽  
Long Period Fiber Gratings ◽  
Fs Laser ◽  
Period Fiber Grating ◽  
Application Fields ◽  
Sensing Characteristics

We propose a novel tilted long period fiber grating (TLPFG) design, inscribed using a line-by-line inscription technique and an infrared femtosecond (Fs) laser. The responses of this TLPFG to external refractive index, temperature, torsion, and strain were systematically investigated to determine its sensing characteristics. The external refractive index (RI) was measured to be −602.86 nm/RIU at an RI of ~1.432. The TLPFG was used to accurately measure temperatures up to 450 °C with a sensitivity of 103.8 pm/°C. The torsion and strain sensitivity of the device were 48.94 nm/(rad/mm) and −0.63 pm/µε, respectively. These results demonstrate that the proposed TLPFG could be used as sensors in a series of application fields including high temperatures and external environments.

scholarly journals Influence of InGaZnO Films with Different Ratios on Refractive Index Sensing Characteristics of LPFG

Coatings ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 978
Author(s):  
Huanhuan Yan ◽  
Li Wang ◽  
Shufeng Li ◽  
Huisong Zhang ◽  
Jin Wang ◽  
...  
Keyword(s):  
Refractive Index ◽  
High Sensitivity ◽  
Fiber Grating ◽  
Fiber Gratings ◽  
Long Period ◽  
Refractive Index Sensing ◽  
Long Period Fiber Gratings ◽  
Optical Fiber Sensing ◽  
Period Fiber Grating ◽  
Sensing Characteristics

Sensitive materials are widely used in the field of optical fiber sensing because of their unique advantages such as rich types, controllable composition ratio and diverse structure distribution. In this paper, the surface of long-period fiber gratings with InGaZnO [(In2O3):(Ga2O3):(ZnO)] nano films with different compositions were coated by pulse laser deposition (PLD) technology. The best sensing ratio and the high sensitivity sensing of the refractive index of long-period fiber grating (LPFG) were achieved through the analysis of the influence of different ratios of InGaZnO nano films on the refractive index sensing characteristics of grating. High sensitivities of 337 nm/RIU (refractive index unit) and 145 dB/RIU of the LPFG are achieved when the best doping ratio of InGaZnO is 7:1:2.

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.

scholarly journals Simulation of the Transmission Spectrum of Long-Period Fiber Gratings Structures with a Propagating Acoustic Shock Front

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7212
Author(s):  
Oleg V. Ivanov ◽  
Paulo Caldas ◽  
Gaspar Rego
Keyword(s):  
Shock Front ◽  
Transmission Spectrum ◽  
Fiber Grating ◽  
Modulation Amplitude ◽  
Fiber Gratings ◽  
Coupled Mode ◽  
Long Period Fiber Grating ◽  
Long Period ◽  
Long Period Fiber Gratings ◽  
Period Fiber Grating

In this paper, we investigate modification of transmission spectra of long-period fiber grating structures with an acoustic shock front propagating along the fiber. We simulate transmission through inhomogeneous long-period fiber gratings, π-shift and reflective π-shift gratings deformed by an acoustic shock front. Coupled mode equations describing interaction of co-propagating modes in a long-period fiber grating structures with inhomogeneous deformation are used for the simulation. Two types of apodization are considered for the grating modulation amplitude, such as uniform and raised-cosine. We demonstrate how the transmission spectrum is produced by interference between the core and cladding modes coupled at several parts of the gratings having different periods. For the π-shift long-period fiber grating having split spectral notch, the gap between the two dips becomes several times wider in the grating with the acoustic wave front than the gap in the unstrained grating. The behavior of reflective long-period fiber gratings depends on the magnitude of the phase shift near the reflective surface: an additional dip is formed in the 0-shift grating and the short-wavelength dip disappears in the π-shift grating.

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.

Potential-Scanning Sensing for Refractive Index Using an Indium Tin Oxide (ITO)-Coated Long-Period Fiber Grating (LPFG)

2021 ◽  
pp. 1-11
Author(s):  
Takuya Okazaki ◽  
Tatsuya Orii ◽  
Shin-Yinn Tan ◽  
Tomoaki Watanabe ◽  
Akira Taguchi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Fiber Grating ◽  
Long Period Fiber Grating ◽  
Long Period ◽  
Period Fiber Grating
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