<title>Heterodyne interferometer for film thickness and refractive index measurements of optical thin film</title>

Abstract Extracting optical parameters from spectrophotometric measurements is a challenging task. In a photometric setup, an unknown thin-film is subjected to an incident light beam for a range of admissible wavelengths, which outputs reflectance and transmittance spectra. The current work attempts to solve an inverse problem of extracting thin-film thickness and complex refractive index from reflectance and transmittance spectra for an incident angle of light. The film thickness is a scalar quantity, and the complex refractive index is composed of real and imaginary parts as functions of wavelengths. We leverage evolutionary optimization techniques to solve the underlying inverse problem, which determines the desired parameters associated with two optical dispersion models: ensemble of Tauc-Lorentz (TL) and ensemble of Gaussian oscillators, such that the generated spectra accurately fit the input data. The optimal parameters involved in the adopted models are determined using efficient evolutionary algorithms (EAs). Numerical results validate the effectiveness of the proposed approach in estimating the optical parameters of interest.

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Design of Optical Thin Film Filter for Sensor Network

Journal of Network and Information Security ◽

10.21863/jnis/2015.3.1.002 ◽

2015 ◽

Vol 3 (1) ◽

Author(s):

Vahideh Khadem Hosseini ◽

Mohammad Taghi Ahmadi

Keyword(s):

Thin Film ◽

Refractive Index ◽

Silicon Dioxide ◽

Human Body ◽

High Refractive Index ◽

Structural Factors ◽

Optical Thin Film ◽

Fabry Perot ◽

Detection Of Objects ◽

Low Refractive Index

Human body detection is very important especially in the countries prone to earthquakes. Fabry-Perot filter as an ideal option in this field needs to be explored. This filter is useful for detection of objects that have temperature around that of the human body. In the presented research, an optical thin film Fabry-Perot filter (FPF) at the wavelength about 8 um to 14 um is investigated. The important factors on transmission spectrum and the band width of filter are discussed. Additionally structural factors such as layers material and their thickness are explored. Various materials with high and low refractive index are examined by TFCalc3.5 for thin film layers. Germanium (Ge) with the refractive index 4.20 is selected for layer with high refractive index and Silicon Dioxide (SiO2) with the refractive index 1.46 is selected for low refractive index layer. Our simulation results lead to optimum parameters as: Germanium layer with 196nm thickness and Silicon Dioxide layer with 451nm thickness. Simulation of proposed filter indicated that the transfer coefficient is more than 90% in desired spectrum. Filter structure can be used on Infrared detectors to improve their resolutions and detection.

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Bare and thin-film-coated substrates with null reflection for p- and s-polarized light at the same angle of incidence: reflectance and ellipsometric parameters as functions of substrate refractive index and film thickness

Applied Optics ◽

10.1364/ao.55.008464 ◽

2016 ◽

Vol 55 (30) ◽

pp. 8464

Author(s):

R. M. A. Azzam

Keyword(s):

Thin Film ◽

Refractive Index ◽

Film Thickness ◽

Polarized Light ◽

Angle Of Incidence

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A NOVEL METHOD FOR PRODUCING NANOSTRUCTURED CdSe THIN FILM

Surface Review and Letters ◽

10.1142/s0218625x19501750 ◽

2019 ◽

Vol 27 (07) ◽

pp. 1950175 ◽

Cited By ~ 1

Author(s):

İSHAK AFŞIN KARİPER

Keyword(s):

Thin Film ◽

Thin Films ◽

Refractive Index ◽

Film Thickness ◽

Sem Analysis ◽

Optical Bandgap ◽

Cdse Thin Film ◽

Glass Substrates ◽

Commercial Glass ◽

Ph Level

In this study, we produced Cadmium selenide (CdSe) crystalline thin film on commercial glass substrates via chemical bath deposition. Transmittance, absorbance, refractive index and optical bandgap of thin films were examined by UV/vis spectrum. XRD revealed a hexagonal form. The pH level of the baths in which CdSe thin films were deposited varied and optical and structural properties of the resulting thin films were analyzed. SEM analysis was used for surface analysis. Some features of the films were supposed to change with pH and these properties were investigated by testing different pH levels, which were 8, 9, 10 and 11. The variation of the optical bandgap changed between 1.60 and 1.75[Formula: see text]eV, according to the pH of deposition bath. Film thickness varied from 60[Formula: see text]nm to 93[Formula: see text]nm, with the variation of deposition bath’s pH. Moreover, it has been found that refractive index values were also changed with film thickness; these were calculated as 2.28, 2.19, 2.22 and 2.36 for 93.27, 60.97, 61.09 and 60.18[Formula: see text]nm, respectively. Dielectric constant also varied with refractive index, taking values 0.85, 0.75, 0.78, 0.93 for refractive indexes 2.28, 2.19, 2.22 and 2.36, respectively.

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