Compact in-reflection fiber interferometer using thermally expanded core fiber and single-mode fiber and its applications as temperature and refractive index sensors

2009 ◽  
Author(s):  
Linh Viet Nguyen ◽  
Youngjoo Chung
Keyword(s):  
Refractive Index ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Core Fiber ◽  
Refractive Index Sensors

Temperature-insensitive intensity-modulation liquid refractive index sensor based on fiber-optic Michelson probe structure

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Chen Zheng ◽  
Wenlin Feng ◽  
Xiaozhan Yang ◽  
Guojia Huang ◽  
Lian Wang ◽  
...  
Keyword(s):  
Refractive Index ◽  
Beam Propagation Method ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Intensity Change ◽  
Refractive Index Sensor ◽  
Silver Mirror ◽  
Core Fiber ◽  
Core Modes ◽  
Theoretical Results

Abstract A novel liquid refractive index sensor based on the connected single-mode fiber (SMF), no-core fiber (NCF), four-core fiber (FCF), and silver mirror (SM) to form an SMF–NCF–FCF–SM Michelson probe structure is proposed and fabricated. The change of light field in the probe structure has been simulated by the light-beam propagation method. The theoretical results show that light is excited in the NCF and couples into the cores and cladding of FCF at the junction of NCF and FCF. The interference fringes are generated between the cladding modes and core modes of FCF. The sensitivities of the probe in NaCl, sucrose, and glycerol are 171.75 dB/RIU, 121.41 dB/RIU, and 207.50 dB/RIU, respectively. The temperature sensitivity is 0.05 nm/°C, and the intensity change of temperature (≤0.046 dB/°C) is very small and has little effect on the liquid refractive index. Thus, the cross-sensitivity of temperature for the liquid refractive index can be removed. The proposed probe structure has the advantages of easy fabrication, good stability, and linear response, having potential application in the liquid refractive index monitoring environments.

scholarly journals Dual Demodulation of Temperature and Refractive Index Using Ring Core Fiber Based Mach-Zehnder Interferometer

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 258
Author(s):  
Weihao Yuan ◽  
Changyuan Yu
Keyword(s):  
Refractive Index ◽  
Extinction Ratio ◽  
Linear Equations ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Zehnder Interferometer ◽  
Wavelength Shift ◽  
Core Fiber ◽  
Ring Core ◽  
Mach Zehnder Interferometer

We report the ring core fiber spliced with single mode fiber and no core fiber which is used for temperature and refractive index (RI) sensing. The Mach-Zehnder interferometer (MZI) is formed with this kind of sandwich fiber structure and the maximum extinction ratio of the interference spectra reaches 27 dB with the free spectra range of 12 nm. The MZI fiber sensor is applied for temperature sensing with the sensitivity of 69 pm/°C and 0.051 dB/°C. The RI sensitivity reaches 182.07 dB/RIU and −31.44 nm/RIU with the RI ranging from 1.33 to 1.38. The RI value can be directly demodulated with the interference dip intensity which shows insensitivity to temperature. The demodulation of temperature can be achieved by using the linear equations between dip wavelength shift with the variation of temperature and RI.

scholarly journals Optimization Design of SNS Sensor Structural Parameters for Battery Expansion Monitoring

2021 ◽  
Vol 9 ◽  
Author(s):  
Shibo Xu ◽  
Zhe Wang ◽  
Hanrui Yang ◽  
Shengxi Jiao ◽  
Jien Liu ◽  
...  
Keyword(s):  
Refractive Index ◽  
Electrolyte Solution ◽  
Optimization Design ◽  
Structural Parameters ◽  
Single Mode ◽  
Measurement Range ◽  
Single Mode Fiber ◽  
Fiber Sensor ◽  
Sensor Structure ◽  
Core Fiber

In this article, a method to improve refractive index (RI) sensitivity of single‐mode–no core–single‐mode fiber (SNS) sensor structure is addressed by optimization of geometric parameters of no-core fiber (NCF), which could be used to accurately measure the irreversible deformation of the battery expansion state caused by temperature change. From the perspective of temperature changing RI of the electrolyte solution, the impacts of diameter, length, and waveband on the performance of the fiber sensor have been discussed as RI measurement range is 1.340–1.390. After optimization, RI sensitivity can reach approximately 2,252.7 and 2037.3 nm/RIU with the length of 6.55 and 6.75 mm when the RI is from 1.380 to 1.390.

Strain, torsion and refractive index sensors based on helical long period fibre grating inscribed in small-core fibre for structural condition monitoring

2021 ◽  
Vol 24 (6) ◽  
pp. 1248-1255
Author(s):  
Cailing Fu ◽  
Yi-Qing Ni ◽  
Tong Sun ◽  
Yiping Wang ◽  
Siqi Ding ◽  
...  
Keyword(s):  
Refractive Index ◽  
High Sensitivity ◽  
Single Mode ◽  
Structural Condition ◽  
Core Diameter ◽  
Small Core ◽  
Long Period ◽  
Sensing Applications ◽  
Core Fibre ◽  
Refractive Index Sensors

This study is intended to develop long period fibre grating sensors for potential applications in environmental and durability monitoring of coastal structures. High-quality helical long period fibre gratings (HLPFGs) are inscribed in different types of small-core single mode fibre (SMF) by use of hydrogen-oxygen flame heating technique. A detailed investigation of the effect of core diameter on their transmission spectrum and optimum length of the HLPFG has been pursued. A longer length is required to achieve the same coupling attenuation in a smaller-core SMF than that of a larger-core fibre. The strain, torsion and refractive index (RI) properties of the HLPFG is investigated experimentally to develop a high-sensitivity sensor. The experimental results show that the strain sensitivity could be enhanced by means of employing a larger-core diameter SMF. Moreover, the HLFPGs are also sensitive to the torsion and external RI. Hence, such HLFPGs have great potential for sensing applications.

Fiber-optic Michelson interferometer based on α-Fe2O3/ZrO2 sensing membrane and its application in trace fluoride-ion detection

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Zizheng Yue ◽  
Wenlin Feng
Keyword(s):  
Silver Film ◽  
Fiber Optic ◽  
Michelson Interferometer ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Ion Concentration ◽  
Fluoride Ion ◽  
Ion Detection ◽  
Core Fiber ◽  
Sensing Membrane

Abstract In this work, a fiber-optic fluoride-ion-detection Michelson interferometer based on the thin-core fiber (TCF) and no-core fiber (NCF) coated with α-Fe2O3/ZrO2 sensing film is proposed and presented. The single-mode fiber (SMF) is spliced with the TCF and NCF in turn, and a waist-enlarged taper is spliced between them. Then, a silver film is plated on the end face of NCF to enhance the reflection. After the absorption of fluoride ion by the sensing film, the effective refractive index (RI) of the coated cladding will change, which leads to the regular red shift of the interference dip with the increasing fluoride-ion concentration. Thus, the fluoride-ion concentrations can be determined according to the corresponding dip wavelength shifts. The results show that the sensor has an excellent linear response (R 2 = 0.995) with good sensitivity (8.970 nm/ppm) when the fluoride-ion concentration is in the range of 0–1.5 ppm. The response time is about 15 s. The sensor has the advantage of good selectivity, good temperature and pH stabilities, and can be applied to detect fluoride ion effectively.

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