scholarly journals Sensitivity Characterization of Cascaded Long-Period Gratings Operating near the Phase-Matching Turning Point

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 5978
Author(s):  
Wei Zhou ◽  
Yanli Ran ◽  
Zhijun Yan ◽  
Qizhen Sun ◽  
Chen Liu ◽  
...  
Keyword(s):  
Refractive Index ◽  
Temperature Sensitivity ◽  
Turning Point ◽  
Phase Matching ◽  
Long Period ◽  
Long Period Gratings ◽  
High Measurement ◽  
Surrounding Refractive Index ◽  
Wavelength Resolution ◽  
Quality Factor Q

We characterized a cascaded long-period gratings (LPGs)-based sensor that was operating at the phase-matching turning point (PMTP). The cascaded LPGs constructed an in-fiber Mach–Zehnder interferometer (MZI), which exhibited a series of high-quality-factor (Q) narrow-bandwidth resonance peaks. As the LPG operated at the PMTP, the proposed sensor showed an ultrahigh refractive index (RI) and temperature sensitivity, and high measurement precision. In this study, we took an in-depth look at the effects of grating separation on Q-factor and sensitivity. The results showed that the sensitivity to the surrounding refractive index (SRI) reached 4741.5 nm/RIU at 1.4255 and 2138 nm/RIU, over the range of 1.335–1.373. In addition, the temperature sensitivity was around 4.84 nm/°C. With a 0.02 nm wavelength resolution, the RI and temperature sensing limits were 9.3 × 10−6 RIU and 5.5 × 10−3 °C.

scholarly journals Sensing Features of Arc-induced Long Period Gratings

Proceedings ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 29
Author(s):  
Esposito ◽  
Srivastava ◽  
Campopiano ◽  
Iadicicco
Keyword(s):  
Refractive Index ◽  
Systematic Investigation ◽  
Proper Selection ◽  
Long Period ◽  
Long Period Gratings ◽  
Surrounding Refractive Index ◽  
Fabrication Parameters ◽  
Selection Of

In this work, we report a systematic investigation about the sensitivity of arc-induced Long Period Gratings in standard SMF28 fiber. Several gratings were fabricated with period Λ in range 330–630 µm and characterized towards changes in the surrounding refractive index (SRI), temperature and strain conditions. Wide tuning of the sensitivities is reported, with maximum values of -6391.7 nm/RIU, 95.5 pm/°C and 2.0 pm/με, respectively, for SRI, temperature and strain. These results permit the proper selection of the fabrication parameters in order to have the desired sensing features for a specific application.

scholarly journals Sensing Characteristics of Side-Hole Fiber-Based Long-Period Grating

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Yi Xin ◽  
Xinyong Dong ◽  
Junwei Yuan ◽  
Yi Li ◽  
Shangzhong Jin ◽  
...  
Keyword(s):  
Refractive Index ◽  
Blue Shift ◽  
Effective Index ◽  
Long Period Grating ◽  
Side Hole ◽  
Long Period ◽  
Long Period Gratings ◽  
Laser Sensing ◽  
Surrounding Refractive Index ◽  
Sensing Characteristics

Long-period gratings (LPGs) have been fabricated in a side-hole fiber (SHF) by using a pulsed CO2laser. Sensing characteristics of this SHF-LPG to temperature surrounding refractive index and bend have been investigated. Experimental results show that resonant wavelength of the SHF-LPG has a blue shift with temperature with sensitivity of −0.11 nm/°C, a blue shift with increasing sensitivity with surrounding refractive index ranging from 1.335 to 1.44 (the maximum sensitivity is achieved when the surrounding refractive index reaches the effective index of the fiber cladding), and a red shift with bend-direction-dependent sensitivity up to 9.36 nm/m−1.

scholarly journals Fabrication of fiber optic long period gratings operating at the phase matching turning point using an ultraviolet laser

2014 ◽  
Vol 53 (21) ◽  
pp. 4669 ◽  
Author(s):  
Rebecca Y. N. Wong ◽  
Edmond Chehura ◽  
Stephen E. Staines ◽  
Stephen W. James ◽  
Ralph P. Tatam
Keyword(s):  
Turning Point ◽  
Fiber Optic ◽  
Phase Matching ◽  
Ultraviolet Laser ◽  
Long Period ◽  
Long Period Gratings

pH Value Detection with CLPFG Sensor

2013 ◽  
Vol 284-287 ◽  
pp. 2157-2161 ◽  
Author(s):  
Chia Chin Chiang ◽  
Cheung Hwa Hsu ◽  
Chao Hui Ou
Keyword(s):  
Refractive Index ◽  
Optical Fiber ◽  
Ph Value ◽  
Ph Sensor ◽  
Fiber Grating ◽  
Long Period ◽  
Systems Chemistry ◽  
Long Period Gratings ◽  
Surrounding Refractive Index ◽  
Target Molecules

Detection of pH value plays an important role in many fields; the precise measurement of pH value is very useful in Living systems, Chemistry and Biochemistry. The purpose of this paper is to measure pH value in solution by using Corrugated Long Period Fiber Grating (CLPFG). The CLPFG element is highly sensitive to refractive index changes, and with appropriate design geometry; a variety of target molecules can then be detected. Optical fiber Corrugated Long Period Gratings are designed to act as spectral loss elements that couple with a discrete wavelength out of the optical fiber as a function of the surrounding refractive index. By applying special coating that change refractive index with absorption of target molecules to the CLPFG surface, it became a transducer for chemical measurement. In this paper, it has shown the incorporation of Polyvinyl Alcohol and Polycyclic Acid (PVA-PAA) with Corrugated Long Period Gratings for the development of a fiber optic-based pH sensor with the detection of pH range from 3 to 6. Optical fiber-based pH sensors offer numerous advantages in wastewater monitoring, remote blood diagnostics, bioremediation, as well as chemical and food processing.

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