Mode Dependence of Refractive Index Sensitivity of Long-Period Fiber Gratings Induced by Periodically Embedded Multimode Fiber

In this article, we present and verify the mode dependence of refractive index (RI) sensitivity of long-period fiber grating induced by periodically embedded multimode fiber (PEM-LPFG). The PEM-LPFG is first fabricated by periodically embedding multimode fiber (MMF) into the single mode fiber (SMF). The resonant mode is translated by reducing the cladding. Numerical simulations based on beam propagation method (BPM) are applied to calculate the transmission spectrum, mode distribution, and RI sensitivities of the PEM-LPFG. The cladding diameter after etching is determined to be 89 and 68 $\mu \text{m}$ , which corresponds to the mode translated from LP012 to LP07 and LP05, respectively. The experimental results indicate that the maximum RI sensitivity of 1322.26 nm/RIU in the range of 1.333–1.437 RIU is achieved when the resonant mode is LP07, which is four times as large as the original one (325.58 nm/RIU @ LP012 mode). PEM-LPFG working at LP05 mode exhibits a lower sensitivity of 844.72 nm/RIU. All of the experimental results are in good agreement with the simulation. The RI sensitivity optimization of PEM-LPFG is able to realize by mode converting. Furthermore, the temperature responses are measured to be 13 pm/°C and 4 pm/°C. This work provides a theoretical reference and experimental evidence for the dependence of the PEM-LPFG RI sensitivity on the resonant mode for the first time.

[1]  Koustav Dey,et al.  Analyzing spectral properties and sensing performance of multi-single-multi mode fiber combination , 2022, Physica Scripta.

[2]  Koustav Dey,et al.  Detailed investigation of spectral properties of SMS fiber segment and its sensing performance under varying multimode fiber lengths , 2022, Infrared Physics & Technology.

[3]  Yulong Li,et al.  Intensity-modulated refractive index sensor based on the side modes of fiber Bragg grating , 2021, Optics Communications.

[4]  C. Chan,et al.  Enhanced Sensitivity Refractometer Based on Spherical Mach–Zehnder Interferometer With Side-Polished Structure , 2021, IEEE Sensors Journal.

[5]  Q. Ling,et al.  Simultaneous SRI and temperature measurement of FM-LPFG written by CO2 laser , 2020 .

[6]  Libo Yuan,et al.  A miniature ultra long period fiber grating for simultaneous measurement of axial strain and temperature , 2020 .

[7]  Libo Yuan,et al.  A Compact Refractometer With High Sensitivity Based on Multimode Fiber Embedded Single Mode-No Core-Single Mode Fiber Structure , 2020, Journal of Lightwave Technology.

[8]  Ying Wang,et al.  Recent Progress in Fabrications and Applications of Heating-Induced Long Period Fiber Gratings , 2019, Sensors.

[9]  Y. Libo,et al.  A miniature SMS-LPG bending sensor with high sensitivity based on multimode fiber embedded-LPG , 2019, Sensors and Actuators A: Physical.

[10]  Libo Yuan,et al.  Optimization and experiment of a miniature multimode fiber induced-LPG refractometer , 2019, OSA Continuum.

[11]  S. Dai,et al.  All-optical switching in long-period fiber grating with highly nonlinear chalcogenide fibers. , 2018, Applied optics.

[12]  Yong Zhao,et al.  Sensitivity-optimized long-period fiber gratings for refractive index and temperature sensing , 2018 .

[13]  S. Idris,et al.  Modal Interferometer Structures and Splicing Techniques of Fiber Optic Sensor , 2018 .

[14]  Stephen W. James,et al.  Sensitivity Enhancement in Low Cutoff Wavelength Long-Period Fiber Gratings by Cladding Diameter Reduction , 2017, Italian National Conference on Sensors.

[15]  Tingyun Wang,et al.  Mode converter based on the long-period fiber gratings written in the six-mode fiber , 2017, 2017 16th International Conference on Optical Communications and Networks (ICOCN).

[16]  Ignacio Del Villar,et al.  Sensitivity optimization with cladding-etched long period fiber gratings at the dispersion turning point. , 2016, Optics express.

[17]  Jose Luis Santos,et al.  Characterization of zinc oxide coated optical fiber long period gratings with improved refractive index sensing properties , 2016 .

[18]  Fang Liu,et al.  Compact Long Period Fiber Grating Based on Periodic Micro-Core-Offset , 2013, IEEE Photonics Technology Letters.

[19]  Weigang Zhang,et al.  Asymmetrically Corrugated Long-Period Gratings by Burning Fiber Coating and Etching Cladding , 2013, IEEE Photonics Technology Letters.

[20]  Predrag Mikulic,et al.  Long period grating based biosensor for the detection of Escherichia coli bacteria. , 2012, Biosensors & bioelectronics.

[21]  Kai Xian Liu,et al.  Technology for EDFA Gain Flattening Based on Long Period Fiber Grating , 2012 .

[22]  Sailing He,et al.  Simultaneous Measurement of Refractive Index and Temperature by Using Dual Long-Period Gratings With an Etching Process , 2007, IEEE Sensors Journal.

[23]  Xiaoming Liu,et al.  Investigation of Acoustooptic Mode Coupling on a Long-Period Fiber Grating , 2006, IEEE Photonics Technology Letters.

[24]  Yiping Wang,et al.  Asymmetric long period fiber gratings fabricated by use of CO2 laser to carve periodic grooves on the optical fiber , 2006 .

[25]  Stephen W James,et al.  Optical fiber long-period gratings with Langmuir-Blodgett thin-film overlays. , 2002, Optics letters.

[26]  Gia-Wei Chern,et al.  Corrugated long-period fiber gratings as strain, torsion, and bending sensors , 2001 .

[27]  Thomas K. Gaylord,et al.  Long-period fibre grating fabrication with focused CO2 laser pulses , 1998 .

[28]  John E. Sipe,et al.  Long-period fiber gratings as band-rejection filters , 1995 .

[29]  Krishna Thyagarajan,et al.  Long period fiber grating based temperature-compensated high performance sensor for bio-chemical sensing applications , 2013 .

[30]  Yi-Ping Wang,et al.  A novel long period fiber grating sensor measuring curvature and determining bend-direction simultaneously , 2005, IEEE Sensors Journal.

[31]  Sang Bae Lee,et al.  Spectral shape tunable band-rejection filter using a long-period fiber grating with divided coil heaters , 2003, IEEE Photonics Technology Letters.