scholarly journals In-Fiber Closed Cavity Interferometric High-Resolution Aqueous Solution and Alcohol Gas Refractometer

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2319 ◽  
Author(s):  
Lijun Li ◽  
Tianzong Xu ◽  
Yinming Liu ◽  
Zhaochuan Zhang ◽  
Qian Ma ◽  
...  
Keyword(s):  
Refractive Index ◽  
Single Mode ◽  
Air Cavity ◽  
Closed Cavity ◽  
Gas Concentration ◽  
Cavity Structure ◽  
Single Cavity ◽  
Index Unit ◽  
Measured Sensitivity ◽  
Low Refractive Index

An optical fiber interferometric refractometer for alcohol gas concentration and low refractive index (RI) solution (with 1.33–1.38 RI range) measurement is theoretically and experimentally demonstrated. The refractometer is based on a single-mode thin-core single-mode (STS) interferometric structure. By embedding a suitably sized air cavity at the splicing point, high-order cladding modes are successfully excited, which makes the sensor more suitable for low RI solution measurement. The effect of the air cavity’s diameter on the sensitivity of alcohol gas concentration was analyzed experimentally, which proved that RI sensitivity will increase with an enlarged diameter of the air cavity. On this basis, the air cavity is filled with graphene in order to improve the sensitivity of the sensor; and the measured sensitivity of the alcohol gas concentration is −1206.1 pm/%. Finally, the characteristics of the single-cavity structure, graphene-filled structure and double-cavity structure sensors are demonstrated, and the linear RI sensitivities are −54.593 nm/RIU (refractive index unit), −85.561 nm/RIU and 359.77 nm/RIU, respectively. Moreover, these sensor structures have the advantages of being compact and easily prepared.

scholarly journals Fiber Optic Refractive Index Sensors Based on a Ball Resonator and Optical Backscatter Interrogation

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6199
Author(s):  
Madina Shaimerdenova ◽  
Takhmina Ayupova ◽  
Marzhan Sypabekova ◽  
Daniele Tosi
Keyword(s):  
Refractive Index ◽  
Reflection Spectrum ◽  
Return Loss ◽  
Fiber Optic ◽  
Single Mode ◽  
Wavelength Shift ◽  
Amplitude Change ◽  
Highly Sensitive ◽  
Refractive Index Sensors ◽  
Index Unit

In this work, we introduced fabrication and interrogation of simple and highly sensitive fiber-optic refractive index (RI) sensors based on ball resonators built on the tip of single-mode fibers. The probes have been fabricated through a CO2 fiber splicer, with a fast (~600 s) and repeatable method. The ball resonator acted as a weak interferometer with a return loss below −50 dB and was interrogated with an optical backscatter reflectometer measuring the reflection spectrum. The ball resonators behaved as weak interferometers with a shallow fringe and a spectrum that appeared close to a random signal, and RI sensitivity could be measured either through wavelength shift or amplitude change. In this work, we reported four samples having sensitivity ranges 48.9–403.3 nm/RIU and 256.0–566.2 dB/RIU (RIU = refractive index unit). Ball resonators appeared as a sensitive and robust platform for RI sensing in liquid and can be further functionalized for biosensing.

scholarly journals Birefringent Bragg Grating in C-Shaped Optical Fiber as a Temperature-Insensitive Refractometer

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3285 ◽  
Author(s):  
Rex Tan ◽  
Daryl Ho ◽  
Chun Tse ◽  
Yung Tan ◽  
Seong Yoo ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Fiber ◽  
Ambient Temperature ◽  
Fiber Bragg Gratings ◽  
Temperature Fluctuations ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Refractive Index Sensitivity ◽  
Index Sensitivity ◽  
Index Unit

We demonstrate a simple-to-fabricate refractometer based on the inscription of fiber Bragg gratings in a special C-shaped optical fiber. The C-shaped fiber was drawn into shape using a quarter cladding removed preform of a commercial standard single-mode fiber by simple machining. The sensor did not suffer from cross-sensitivity of the refractive index with ambient temperature fluctuations, commonly occurring with many optical fiber refractometers. A refractive index sensitivity of 1300 pm per refractive index unit (RIU) was achieved without employing any additional sensitization techniques such as tapering or etching.

scholarly journals High Sensitivity Refractometer Based on a Tapered-Single Mode-No Core-Single Mode Fiber Structure

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1722 ◽  
Author(s):  
Yang ◽  
Zhang ◽  
Geng ◽  
Li ◽  
Li ◽  
...  
Keyword(s):  
Refractive Index ◽  
Contrast Ratio ◽  
High Sensitivity ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Experimental Investigations ◽  
Multimode Interference ◽  
Fiber Structure ◽  
Index Unit ◽  
Good Agreement

We have proposed a novel tapered-single mode-no core-single mode (TSNS) fiber refractometer based on multimode interference. The TSNS structure exhibits a high contrast ratio (＞15 dB) and a uniform interference fringe. The influence of different lengths and diameters of the TSNS on the refractive index unit (RIU) sensitivity was investigated. The experimental investigations indicated a maximum sensitivity of 1517.28 nm/RIU for a refractive index of 1.417 and low-temperature sensitivity (＜10 pm/ºC). The experimental and simulation results are also in good agreement.

Xylene-Cellulose Caprate as a Histologic Mounting Medium of Low Refractive Index

1955 ◽  
Vol 30 (3) ◽  
pp. 133-134 ◽  
Author(s):  
R. D. Lillie ◽  
J. P. Greco Henson
Keyword(s):  
Refractive Index ◽  
Low Refractive Index

scholarly journals Giant refractometric sensitivity by combining extreme optical Vernier effect and modal interference

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
André D. Gomes ◽  
Jens Kobelke ◽  
Jörg Bierlich ◽  
Jan Dellith ◽  
Manfred Rothhardt ◽  
...  
Keyword(s):  
State Of The Art ◽  
Single Mode ◽  
High Magnification ◽  
Magnification Factor ◽  
Detection Systems ◽  
Current State ◽  
Modal Interference ◽  
Vernier Effect ◽  
Index Unit ◽  
Conventional Detection

Abstract The optical Vernier effect consists of overlapping responses of a sensing and a reference interferometer with slightly shifted interferometric frequencies. The beating modulation thus generated presents high magnified sensitivity and resolution compared to the sensing interferometer, if the two interferometers are slightly out of tune with each other. However, the outcome of such a condition is a large beating modulation, immeasurable by conventional detection systems due to practical limitations of the usable spectral range. We propose a method to surpass this limitation by using a few-mode sensing interferometer instead of a single-mode one. The overlap response of the different modes produces a measurable envelope, whilst preserving an extremely high magnification factor, an order of magnification higher than current state-of-the-art performances. Furthermore, we demonstrate the application of that method in the development of a giant sensitivity fibre refractometer with a sensitivity of around 500 µm/RIU (refractive index unit) and with a magnification factor over 850.

scholarly journals A Highly Sensitive SPR Sensors Based on Two Parallel PCFs for Low Refractive Index Detection

2018 ◽  
Vol 10 (4) ◽  
pp. 1-10 ◽  
Author(s):  
Famei Wang ◽  
Chao Liu ◽  
Zhijie Sun ◽  
Tao Sun ◽  
Banghua Liu ◽  
...  
Keyword(s):  
Refractive Index ◽  
Highly Sensitive ◽  
Low Refractive Index ◽  
Refractive Index Detection

scholarly journals Air-trench splitters for ultra-compact ring resonators in low refractive index contrast waveguides

2008 ◽  
Vol 16 (1) ◽  
pp. 456 ◽  
Author(s):  
Nazli Rahmanian ◽  
Seunghyun Kim ◽  
Yongbin Lin ◽  
Gregory P. Nordin
Keyword(s):  
Refractive Index ◽  
Ring Resonators ◽  
Compact Ring ◽  
Refractive Index Contrast ◽  
Index Contrast ◽  
Low Refractive Index
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