Long Period Grating-Based Fiber Coupling to WGM Microresonators for Sensing Applications

A comprehensive model for designing robust all-in-fiber microresonator-based optical sensing setups is illustrated. The investigated all-in-fiber setups allow light to selectively excite high-Q whispering gallery modes (WGMs) into optical microresonators, thanks to a pair of identical long period gratings (LPGs) written in the same optical fiber. Microspheres and microbubbles are used as microresonators and evanescently side-coupled to a thick fiber taper, with a waist diameter of about 18 µm, in-between the two LPGs. The model is validated by comparing the simulated results with the experimental data. A good agreement between the simulated and experimental results is obtained. As an application example, the sensing of the concentration of an aqueous glycerol solution is demonstrated. The model is general and by exploiting the refractive index and/or absorption characteristics at suitable wavelengths, the sensing of other substances or pollutants can be also predicted.

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Long Period Grating-Based Fiber Coupling to WGM Microresonators

Micromachines ◽

10.3390/mi9070366 ◽

2018 ◽

Vol 9 (7) ◽

pp. 366 ◽

Cited By ~ 8

Author(s):

Francesco Chiavaioli ◽

Dario Laneve ◽

Daniele Farnesi ◽

Mario Falconi ◽

Gualtiero Nunzi Conti ◽

...

Keyword(s):

Whispering Gallery Modes ◽

Long Period Grating ◽

High Q ◽

Optical Microresonators ◽

Whispering Gallery ◽

Long Period ◽

Thick Fiber ◽

Long Period Gratings ◽

Fiber Taper ◽

Good Agreement

A comprehensive model for designing robust all-in-fiber microresonator-based optical sensing setups is illustrated. The investigated all-in-fiber setups allow light to selectively excite high-Q whispering gallery modes (WGMs) into optical microresonators, thanks to a pair of identical long period gratings (LPGs) written in the same optical fiber. Microspheres and microbubbles are used as microresonators and evanescently side-coupled to a thick fiber taper, with a waist diameter of about 18 µm, in between the two LPGs. The model is validated by comparing the simulated results with the experimental data. A good agreement between the simulated and experimental results is obtained. The model is general and by exploiting the refractive index and/or absorption characteristics at suitable wavelengths, the sensing of several substances or pollutants can be predicted.

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Temperature compensated long-period gratings for biochemical sensing applications

Optical Sensors and Biophotonics ◽

10.1364/acp.2011.83110a ◽

2011 ◽

Author(s):

Shaorui Gao ◽

Yebin Zhang ◽

A. Ping Zhang

Keyword(s):

Long Period ◽

Biochemical Sensing ◽

Sensing Applications ◽

Long Period Gratings

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

Advances in Materials Science and Engineering ◽

10.1155/2013/850293 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 4

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.

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Microfiber Mach-Zehnder interferometer based on long period grating for sensing applications

Optics Express ◽

10.1364/oe.21.000154 ◽

2013 ◽

Vol 21 (1) ◽

pp. 154 ◽

Cited By ~ 67

Author(s):

Yanzhen Tan ◽

Li-Peng Sun ◽

Long Jin ◽

Jie Li ◽

Bai-Ou Guan

Keyword(s):

Zehnder Interferometer ◽

Long Period Grating ◽

Long Period ◽

Sensing Applications ◽

Mach Zehnder Interferometer

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The study of long period gratings for improved refractive index sensing applications

10.32657/10356/61307 ◽

2013 ◽

Author(s):

Anthony Lim

Keyword(s):

Refractive Index ◽

Long Period ◽

Refractive Index Sensing ◽

Sensing Applications ◽

Long Period Gratings

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Optical Fiber Interferometers Based on Arc-Induced Long Period Gratings at INESC TEC

Sensors ◽

10.3390/s21217400 ◽

2021 ◽

Vol 21 (21) ◽

pp. 7400

Author(s):

Paulo Caldas ◽

Gaspar Rego

Keyword(s):

Refractive Index ◽

Optical Fiber ◽

Cavity Length ◽

Fiber Optic ◽

Fiber Diameter ◽

Long Period Grating ◽

Long Period ◽

Long Period Gratings ◽

Cladding Mode ◽

Mode A

In this work, we review the most important achievements of an INESC TEC long-period-grating-based fiber optic Michelson and Mach–Zehnder configuration modal interferometer with coherence addressing and heterodyne interrogation as a sensing structure for measuring environmental refractive index and temperature. The theory for Long Period Grating (LPG) interferometers and coherence addressing and heterodyne interrogation is presented. To increase the sensitivity to external refractive index and temperature, several LPG interferometers parameters are studied, including order of cladding mode, a reduction of the fiber diameter, different type of fiber, cavity length and the antisymmetric nature of cladding modes.

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