scholarly journals Humidity Sensor Based on a Long-Period Fiber Grating Coated with Polymer Composite Film

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2263 ◽  
Author(s):  
Yunlong Wang ◽  
Yunqi Liu ◽  
Fang Zou ◽  
Chen Jiang ◽  
Chengbo Mou ◽  
...  
Keyword(s):  
Composite Films ◽  
Resonance Wavelength ◽  
Fiber Grating ◽  
Surface Absorption ◽  
Long Period Fiber Grating ◽  
Long Period ◽  
Compact Size ◽  
Wide Range ◽  
Strong Surface ◽  
Period Fiber Grating

We demonstrate a simple and highly sensitive optical fiber relative humidity (RH) sensor based on a long-period fiber grating (LPFG) coated with polyethylene glycol (PEG)/polyvinyl alcohol (PVA) composite films. The resonance wavelength of the LPFG is sensitive to environmental humidity due to the change in effective refractive index caused by the strong surface absorption and desorption of the porous PEG/PVA coatings. The sensor is sensitive in a wide range from 50% to 95% RH, with a highest sensitivity of 2.485 nm/%RH in the range 50–75% RH. The proposed RH sensor has the advantages of compact size, good reversibility, and stability, which makes it attractive for high-humidity environments.

Research on Temperature Compensation for Long-Period Fiber Grating with Strain Property

2011 ◽  
Vol 340 ◽  
pp. 378-382
Author(s):  
Zhi Wei Hou ◽  
Y. Wang ◽  
B. Zhou
Keyword(s):  
Temperature Compensation ◽  
Resonance Wavelength ◽  
Temperature Characteristic ◽  
Resonant Wavelength ◽  
Experimental Result ◽  
Fiber Grating ◽  
Strain Property ◽  
Long Period Fiber Grating ◽  
Long Period ◽  
Period Fiber Grating

In this paper, we demonstrate an effective method to compensate the temperature effect of long period fiber grating (LPFG). First it is found that the resonant wavelength of LPFG showes a right shift when the temperature increases while it has an opposite shift when the applied strain increases. On the basis of the characteristic, plexiglass is used to compensate the shift of the resonant wavelength induced by the tempera-ture change. The temperature characteristic of compensated LPFG has been performed. And the compensa-tion experimental result shows the temperature sensitivity of the resonance wavelength of LPFG is reduced from 55.71pm/°C to 3.7pm/°C. It is found that the method to compensate temperature is effective and prac-tical.

Intensity dependent spectral properties of long-period fiber grating for applications in lightwave communication

2019 ◽  
Vol 28 (02) ◽  
pp. 1950010
Author(s):  
Vishal Jain ◽  
Santosh Pawar ◽  
Shubhada Kumbhaj ◽  
Pranay Kumar Sen
Keyword(s):  
Spectral Properties ◽  
Resonance Wavelength ◽  
Optical Nonlinearity ◽  
Excitation Intensity ◽  
Fiber Grating ◽  
Coupled Mode ◽  
Long Period Fiber Grating ◽  
Long Period ◽  
Cladding Mode ◽  
Period Fiber Grating

Using nonlinear coupled mode equations, the spectral properties of long-period fiber grating are studied analytically taking into account the Kerr type optical nonlinearity in the medium. The nonlinear coupled-mode equations were solved for co-propagating core and cladding mode amplitudes and expressions for transmittivity and phase factor at high excitation intensity are obtained. It is observed that the resonance wavelength of grating shifts towards higher wavelength side with increasing excitation intensity. Also, the minimum transmittivity of the grating shows oscillating behavior with increasing grating length, whereas the phase of the transmitted wave increases monotonically with length at high input intensities.

A Demodulation Scheme for High-Sensitivity Temperature Sensing Based on Long Period Fiber Grating

2011 ◽  
Vol 216 ◽  
pp. 523-527
Author(s):  
Hong Xia Zhao ◽  
Li Wei ◽  
Zhi Qun Ding
Keyword(s):  
Low Cost ◽  
High Sensitivity ◽  
Pulse Interval ◽  
Fiber Grating ◽  
Practical Applications ◽  
Long Period Fiber Grating ◽  
Long Period ◽  
Wide Range ◽  
Signal Demodulation ◽  
Period Fiber Grating

Long Period Fiber Grating (LPFG) sensors have wide range of potential applications; low-cost and high-sensitivity demodulation technology is the key of its practical applications. In this paper, an interferometer is comprised of an all-fiber loop mirror and two identical LPFGs, a tunable F-P filter is used to perform wavelength scanning one of the interference peaks, two negative pulse interval formed by signal light in the drive signal period are measured by means of detector and oscilloscope to realize signal demodulation. This demodulation system was used to detect the temperature parameter. The results showed that the sensing sensitivity of this system was demonstrated to be 0.08349 ms/°C, experimentally, which was 2.3 times higher than a single LPFG using the same demodulation technology.

Simultaneous Measurement of Torsion and Temperature Based on π-Phase-Shifted Long-Period Fiber Grating Inscribed on Double-Clad Fiber

2021 ◽  
Vol 21 (8) ◽  
pp. 4243-4251
Author(s):  
Jinsil Han ◽  
Jihoon Kim ◽  
Seul-Lee Lee ◽  
Sungwook Choi ◽  
Yong Wook Lee
Keyword(s):  
Simultaneous Measurement ◽  
Room Temperature ◽  
Twist Angle ◽  
Optical Fiber Sensor ◽  
Resonance Wavelength ◽  
Fiber Grating ◽  
Long Period Fiber Grating ◽  
Long Period ◽  
Period Fiber Grating ◽  
Temperature Responses

In this work, we experimentally demonstrated an optical fiber sensor capable of performing simultaneous measurement of torsion and temperature using a π-phase-shifted long-period fiber grating (LPFG) inscribed on double-clad fiber (DCF), referred to as a PS-DC-LPFG. The fabricated PSDC- LPFG showed split attenuation bands near its resonance wavelength, and the two dips in these bands were selected as sensor indicators, denoted as Dips A and B, for the simultaneous measurement of torsion and temperature. The torsion and temperature responses of the two indicators were investigated in a twist angle range from −360° to 360° and a temperature range from 30 to 120 °C, respectively. When the twist angle increased from 0° to 360° (clockwise) at room temperature, both Dips A and B showed redshifts. On the contrary, when the twist angle decreased from 0° to −360° (counterclockwise), the two dips showed blueshifts. In terms of temperature responses, both dips showed redshifts with increasing ambient temperature while the sensor head (i.e., the PS-DC-LPFG) remained straight without any applied torsion. Owing to their linear and independent responses to torsion and temperature, the changes in torsion and temperature applied to the PSDC- LPFG could be simultaneously estimated from the measured wavelength shifts and calculated sensitivities of the two indicator dips.

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