Evaluation of Refractive Index from Interference-Fringe Transmission Spectra

AbstractThe growth of AlN layers on glass substrates using magnetron sputtering method was performed and the grown layers were subjected to optical measurements. Transmission spectra of the layers grown at different content of N2 in the atmosphere were obtained. The transmission spectra as well as energy gap depended on N2 content. The annealing of the layers in air led to transmission changes and influenced energy gap and refractive index values.

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Спектроскопия слоев на плоскопараллельных подложках

Журнал технической физики ◽

10.21883/os.2020.08.49711.79-20 ◽

2020 ◽

Vol 128 (8) ◽

pp. 1133

Author(s):

А.Б. Сотский ◽

С.С. Михеев ◽

Н.И. Стаськов ◽

Л.И. Сотская

Keyword(s):

Zinc Oxide ◽

Refractive Index ◽

Thin Layers ◽

Transmission Spectra ◽

Coherent Light ◽

Polarized Waves ◽

Partially Coherent Light ◽

Aluminum Doped Zinc Oxide ◽

Analytical Formulae ◽

Oblique Illumination

Integral expressions for the reflectance and transmittance spectra of the structure consisted of two thin layers deposited on opposite faces of a plane-parallel substrate at oblique illumination of the structure with partially coherent light are obtained. As a result of the asymptotic analysis of the integrals, approximate analytical formulae are established for calculating the indicated spectra, convenient for use in solving inverse spectrophotometry problems. An aluminum doped zinc oxide layer deposited on a glass substrate is studied. The spectra of the refractive index and absorption coefficient of the layer and the substrate, as well as the thickness of the layer, are determined by processing the reflectance and transmission spectra of the structure, measured for s- and p- polarized waves at two angles of light incidence. The found parameters are used in computational experiments to estimate the applicability limits of the formulated approximations.

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Automatic Characterization of the Refractive Index Profile of Fibers by Interferometry

International Nonwovens Journal ◽

10.1177/1558925002os-01100106 ◽

2002 ◽

Vol os-11 (1) ◽

pp. 1558925002OS-01

Author(s):

Han Seong Kim ◽

Behnam Pourdeyhimi

Keyword(s):

Refractive Index ◽

Interference Fringe ◽

Axial Direction ◽

Refractive Index Profile ◽

Path Difference ◽

Fringe Field ◽

Index Profile ◽

Degree Of Orientation ◽

Non Destructive

Interferometry provides a non-destructive method for examining the refractive index profile or the radial birefringence distribution within fibers. The key step in the interference data reduction involves the extraction of the refractive index profile along the axial direction of the fiber. The profile is due to the path difference between the fiber and the immersion liquid when a fiber is oriented perpendicular to the fringe field in an interference microscope. The refractive index provides a measure of the degree of optical anisotropy and is indicative of the degree of orientation of the structure. This is of particular interest to nonwovens because in thermally bonded nonwovens, the orientation plays a major role in how well the fibers are bonded and the ultimate properties of the fabric. Despite its long history, however, the interpretation of the interference fringe shift is not precisely defined. Consequently, the data are not reproducible from one laboratory to the next. We outline below an objective and quantitative method for precisely measuring a fiber's refractive index profile from a digitized image of the interference fringe. This new algorithm uses the Fast Fourier Transform (FFT) to remove the inherent noise present in the fiber interferogram and to aid in extracting the profile.

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Research on Fused Tapered Photonic Crystal Fiber Sensor Based on the Method of Intermittent Cooling

Journal of Sensors ◽

10.1155/2016/7353067 ◽

2016 ◽

Vol 2016 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Guangwei Fu ◽

Xinghu Fu ◽

Peng Guo ◽

Yushen Ji ◽

Weihong Bi

Keyword(s):

Refractive Index ◽

Photonic Crystal ◽

Photonic Crystal Fiber ◽

Glycerol Solution ◽

Transmission Spectra ◽

Refractive Index Sensitivity ◽

Fringe Contrast ◽

Crystal Fiber ◽

Heating And Cooling ◽

Index Sensitivity

Based on the intermittent cooling method, a fused tapered Photonic Crystal Fiber (PCF) interferometer is proposed. In the process of tapering, stop heating and wait for cooling at different taper length. Repeat heating and cooling, until taper goes to the expected length. Compared with the ordinary fused tapered method, the fringe contrast of the transmission spectra of this sensor is 15.06 dB. The transmission spectra in different concentrations of glycerol solution are obtained, and the temperature cross-sensitivity of the sensor is studied. The experimental results show that as the external refractive index increases, the transmission spectra of the sensor shift to longer wavelength. In the measuring glycerol solution, the refractive index sensitivity of the sensor can achieve 797.674 nm/RIU, and the temperature sensitivity is only 0.00125 nm/°C.

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