scholarly journals A Fiber-Optic Gas Sensor and Method for the Measurement of Refractive Index Dispersion in NIR

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3717 ◽  
Author(s):  
Matej Njegovec ◽  
Denis Donlagic
Keyword(s):  
Refractive Index ◽  
Optical Fibers ◽  
Near Infrared ◽  
Optical Design ◽  
Infrared Region ◽  
Refractive Index Dispersion ◽  
Measurement Resolution ◽  
Fabry Perot ◽  
Good Potential ◽  
Cost Efficient

This paper presents a method for gas concentration determination based on the measurement of the refractive index dispersion of a gas near the gas resonance in the near-infrared region (NIR). The gas refractive index dispersion line shape is reconstructed from the variation in the spectral interference fringes’ periods, which are generated by a low-finesse Fabry-Perot interferometer during the DFB diode’s linear-over-time optical frequency sweep around the gas resonance frequency. The entire sensing system was modeled and then verified experimentally, for an example of a low concentration methane-air mixture. We demonstrate experimentally a refractive index dispersion measurement resolution of 2 × 10−9 refractive index units (RIU), which corresponds to a change in methane concentration in air of 0.04 vol% at the resonant frequency of 181.285 THz (1653.7 nm). The experimental and modeling results show an excellent agreement. The presented system utilizes a very simple optical design and has good potential for the realization of cost-efficient gas sensors that can be operated remotely through standard telecom optical fibers.

scholarly journals Wide Range Refractive Index Sensor Using a Birefringent Optical Fiber

2021 ◽  
Author(s):  
Moutusi De ◽  
Vinod Kumar Singh
Keyword(s):  
Refractive Index ◽  
Near Infrared ◽  
High Sensitivity ◽  
Infrared Region ◽  
Device Fabrication ◽  
Refractive Index Sensor ◽  
Potential Candidate ◽  
Wide Range ◽  
Analyte Detection ◽  
Birefringent Optical Fiber

Abstract In this article, an efficient high birefringent D-shaped photonic crystal fiber (HB-D-PCF) plasmonic refractive index sensor is reported. It is able to work over a long low refractive index (RI) analyte range from 1.29 to 1.36. This modified simple structured hexagonal PCF has high birefringence in the near-infrared region. A thin gold film protected by a titanium dioxide (TiO2) layer is deposited on the D-surface of the PCF which acts as surface plasmon active layer. The sensor consists of an analyte channel on the top of the fiber. The performance of the HB-D-PCF is analyzed based on finite element method (FEM). Both wavelength and amplitude interrogation techniques are applied to study the sensing performance of the optimized sensor. Numerical results show wavelength and amplitude sensitivity of 9245nm/RIU and 1312 RIU-1 respectively with high resolution. Owing to the high sensitivity, long range sensing ability as well as spectral stability the designed HB-D-PCF SPR sensor is a potential candidate for water pollution control, glucose concentration testing, biochemical analyte detection as well as portable device fabrication.

Refractive Index Dispersion of Hexagonal Boron Nitride in the Visible and Near‐Infrared

2018 ◽  
Vol 256 (6) ◽  
pp. 1800417 ◽  
Author(s):  
Seong‐Yeon Lee ◽  
Tae‐Young Jeong ◽  
Suyong Jung ◽  
Ki‐Ju Yee
Keyword(s):  
Refractive Index ◽  
Boron Nitride ◽  
Near Infrared ◽  
Hexagonal Boron Nitride ◽  
Refractive Index Dispersion

Non-Destructive Spectroscopic Investigations on Paintings Using Optical Fibers

1992 ◽  
Vol 267 ◽  
Author(s):  
M. Bacci ◽  
S. Baronti ◽  
A. Casini ◽  
F. Lotti ◽  
M. Picollo ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Near Infrared ◽  
Far Infrared ◽  
Infrared Region ◽  
Infrared Range ◽  
Color Analysis ◽  
Near Infrared Spectra ◽  
Renaissance Period ◽  
Band Pass ◽  
Non Destructive

ABSTRACTThe main objective of our research is the development of totally non-destructive methodologies for the investigation of art works. We propose the use of fiber optic reflectance spectroscopy (FORS) in the visible and near-infrared region as a tool for the identification of the pigments used in painting. We have considered several representative inorganic artists' pigments (mainly till the Renaissance period); powder X-ray diffractograms and diffuse reflectance spectra in the visible, near-, middle- and far-infrared range were recorded for pure pigments. Then we prepared suitable samples with the same pigments using fresco, tempera and oil techniques. The visible and near-infrared spectra of these samples were recorded using an optical fiber spectrum analyzer; color analysis (chromaticity, dominant wavelength and purity) was also performed. The obtained results were used in the interpretation of the spectra obtained from some paintings collected in the Uffizi Gallery, Florence (Giotto and Luca Signorelli). The pointwise information obtained by FORS analysis was also used to calibrate and tune an image spectroscopy system, based on sequences of band-pass filtered images in the near infrared range.

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