Combined long-period grating and micro-cavity in-line Mach-Zehnder interferometer for refractive index sensing

2017 ◽  
Author(s):  
Monika Janik ◽  
Marcin Koba ◽  
Predrag Mikulic ◽  
Wojtek J. Bock ◽  
Mateusz Śmietana
Keyword(s):  
Refractive Index ◽  
Zehnder Interferometer ◽  
Long Period Grating ◽  
Long Period ◽  
Refractive Index Sensing ◽  
Micro Cavity ◽  
Mach Zehnder Interferometer

scholarly journals Combined Long-Period Fiber Grating and Microcavity In-Line Mach–Zehnder Interferometer for Refractive Index Measurements with Limited Cross-Sensitivity

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2431 ◽  
Author(s):  
Monika Janik ◽  
Marcin Koba ◽  
Krystian Król ◽  
Predrag Mikulic ◽  
Wojtek J. Bock ◽  
...  
Keyword(s):  
Refractive Index ◽  
High Efficiency ◽  
Single Mode ◽  
Zehnder Interferometer ◽  
Fiber Grating ◽  
Long Period Grating ◽  
Cross Sensitivity ◽  
Long Period ◽  
Period Fiber Grating ◽  
Mach Zehnder Interferometer

This work discusses sensing properties of a long-period grating (LPG) and microcavity in-line Mach–Zehnder interferometer (µIMZI) when both are induced in the same single-mode optical fiber. LPGs were either etched or nanocoated with aluminum oxide (Al2O3) to increase its refractive index (RI) sensitivity up to ≈2000 and 9000 nm/RIU, respectively. The µIMZI was machined using a femtosecond laser as a cylindrical cavity (d = 60 μm) in the center of the LPG. In transmission measurements for various RI in the cavity and around the LPG we observed two effects coming from the two independently working sensors. This dual operation had no significant impact on either of the devices in terms of their functional properties, especially in a lower RI range. Moreover, due to the properties of combined sensors two major effects can be distinguished—sensitivity to the RI of the volume and sensitivity to the RI at the surface. Considering also the negligible temperature sensitivity of the µIMZI, it makes the combination of LPG and µIMZI sensors a promising approach to limit cross-sensitivity or tackle simultaneous measurements of multiple effects with high efficiency and reliability.

scholarly journals Up-down Taper Based In-Fiber Mach-Zehnder Interferometer for Liquid Refractive Index Sensing

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5440 ◽  
Author(s):  
Xiaopeng Han ◽  
Chunyu Liu ◽  
Shengxu Jiang ◽  
Shuo Leng ◽  
Jiuru Yang
Keyword(s):  
Refractive Index ◽  
Temperature Fluctuation ◽  
Extinction Ratio ◽  
Single Mode ◽  
Zehnder Interferometer ◽  
Structure Parameters ◽  
Refractive Index Sensing ◽  
Polarization Maintaining Fiber ◽  
Polarization Maintaining ◽  
Mach Zehnder Interferometer

A novel in-fiber Mach-Zehnder interferometer based on cascaded up-down-taper (UDT) structure is proposed by sandwiching a piece of polarization maintaining fiber between two single-mode fibers (SMF) and by utilizing over-fusion splicing method. The dual up tapers respectively act as fiber splitter/combiner, the down taper acts as an optical attenuator. The structure parameters are analyzed and optimized. A larger interference fringe extinction ratio ~15 dB is obtained to achieve refractive index (RI) sensing based on intensity demodulation. The experimental results show that the RI sensitivity is −310.40 dB/RIU with the linearity is improved to 0.99 in the range of 1.3164–1.3444. The corresponding resolution can reach 3.22 × 10−5 RIU, which is 6.8 times higher than wavelength demodulation. The cross sensitivity which caused by temperature fluctuation is less than 1.4 × 10−4.

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