Special Issue "Design, Manufacturing and Measurement of Optical Film Coatings"

A special issue of Coatings (ISSN 2079-6412).

Deadline for manuscript submissions: 31 July 2019

Special Issue Editor

Guest Editor
Prof. Yi-Jun Jen

Department of Electro-Optical Engineering, National Taipei University of Technology, Taipei, Taiwan
Website | E-Mail
Interests: optical coatings of metamaterials; dielectric anisotropic thin films; novel polarization devices; surface plasmon resonance; 2-D and 3-D nanosculptured thin film

Special Issue Information

Dear Colleagues,

Optical coatings have been widely applied in various optical devices to perform antireflection, high reflection, beam splitting, and bandpass filtering. Due to rapid progress of science and engineering, optical coatings are desired that offer more advanced performances, such as ultra-thin perfect absorption, perfect phase retardation, and wide angle bandpass filtering. It is expected that diverse nanostructures and more materials appear in coatings to support various needs. In order to detect the optical properties of thin films, new techniques for measuring complex structured thin films have also been developed.

Potential topics for this Special Issue include, but are not limited to:

(1) Novel applications in light harvest, lighting, 3D recognition, bio-sensing and display

(2) Design, fabrication and application for layered metamaterials

(3) New measurement and analysis for nanostructured thin films

(4) Novel function prediction based on precise simulations

(5) Bio-mimic and bio-inspired optical coatings

Contributions to this Special Issue are welcomed on all subjects related to including design, manufacturing and measurement of manufacturing of optical thin film coatings. Especially, welcome are papers that raise new questions and new possibilities or examine old problems from a new angle.

Prof. Yi-Jun Jen
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (7 papers)

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Research

Open AccessArticle
Study of Birefringence and Stress Distribution of SiO2 Film Optical Waveguide on Silicon Wafer
Coatings 2019, 9(5), 316; https://doi.org/10.3390/coatings9050316
Received: 10 April 2019 / Revised: 5 May 2019 / Accepted: 8 May 2019 / Published: 10 May 2019
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Abstract
Silica waveguide planar lightwave circuit (PLC) technology is driving the broad applications of various functional components to meet the increasing demands of the industry due to its advanced performance in large-scale wafer mass production. Despite the intense research interests in understanding and relaxing [...] Read more.
Silica waveguide planar lightwave circuit (PLC) technology is driving the broad applications of various functional components to meet the increasing demands of the industry due to its advanced performance in large-scale wafer mass production. Despite the intense research interests in understanding and relaxing the stress causing the optical birefringence, not much research has been devoted to investigating the stress distribution. In this article, the thermal stress, growth-caused stress, and structural stress are comparably studied. The birefringence distribution of a 6 μm-thick SiO2 film from the center to the edge on a 6-inch silicon wafer was measured to be 0.0006 to 0.0038, leading to an equivalent stress distribution cross the wafer from −170 to −1000 MPa. This implies that the compressive stress of the thick SiO2 film on the wafer was nonuniformly distributed; however, it gradually increased from the center to the edge. Meanwhile, the measured stress of a SiO2 film decreased with the flow rate of the doped GeH4 gas. The algebraic sum of the above three stresses reached excellent agreement with the measurement results in both distribution form and amplitude. In both research and production, the agreeable optical property distributions between the theoretical calculations and experimental measurements are more sustainable to further improving the yields of SiO2 thick film PLC products. Full article
(This article belongs to the Special Issue Design, Manufacturing and Measurement of Optical Film Coatings)
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Open AccessArticle
Development of Belt-Type Microstructure Array Flexible Mold and Asymmetric Hot Roller Embossing Process Technology
Coatings 2019, 9(4), 274; https://doi.org/10.3390/coatings9040274
Received: 18 March 2019 / Revised: 19 April 2019 / Accepted: 20 April 2019 / Published: 22 April 2019
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Abstract
This study proposed the belt-type microstructure array flexible mold designed hot roller embossing process technology. An extrusion molding system was integrated with belt-type hot roller embossing process technology and, deriving the asymmetric principle as the basis of prediction, designed a belt-type microstructure array [...] Read more.
This study proposed the belt-type microstructure array flexible mold designed hot roller embossing process technology. An extrusion molding system was integrated with belt-type hot roller embossing process technology and, deriving the asymmetric principle as the basis of prediction, designed a belt-type microstructure array hot roller embossing process system. This study first focused on the design and manufacturing of a belt-type hot roller embossing process system (roll to belt-type). It then carried out system integration and testing, along with the film extrusion system, to fabrication microstructure array production. Hot embossing was used to replicate the array of the plastic micro lens as the microstructure mold. The original master mold was fabricated with micro electromechanical technology and the PC micro lens array as the microstructure (inner layer) film using the gas-assisted hot embossing technology. A microstructure composite belt and magnetic belt were produced on the hot roller embossing by an innovated coated casting technique. The forming accuracy of the belt-type microstructure array flexible mold hot roller embossing process and the prediction precision of numerically simulated forming were discussed. The proposed process technology is expected to effectively reduce the process cycle time with the advantages of being a fast and continuous process. Full article
(This article belongs to the Special Issue Design, Manufacturing and Measurement of Optical Film Coatings)
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Open AccessArticle
Analysis of High-Efficiency Mo-Based Solar Selective Absorber by Admittance Locus Method
Coatings 2019, 9(4), 256; https://doi.org/10.3390/coatings9040256
Received: 28 February 2019 / Revised: 10 April 2019 / Accepted: 13 April 2019 / Published: 17 April 2019
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Abstract
High absorptivity and low emissivity are characteristics needed in an ideal solar selective absorber. In high-temperature applications, such as a solar concentration power system in which the solar surface works under a long-term high temperature (about 400 to 800 °C), the absorber material [...] Read more.
High absorptivity and low emissivity are characteristics needed in an ideal solar selective absorber. In high-temperature applications, such as a solar concentration power system in which the solar surface works under a long-term high temperature (about 400 to 800 °C), the absorber material has to maintain high absorption in the visible region, high reflectance in the infrared region, and excellent thermal stability at high temperature. In this research, the design of a molybdenum-based (Mo-based) solar selective absorber was analyzed by the admittance locus method, and the films were deposited by magnetron sputtering. The ratio of the extinction coefficient to the refractive index of the Mo layer was close to 1, so that the Mo-based solar selective absorber had a broad absorption band, high absorption, and good solar selectivity. Its average reflectance in the visible region was less than 0.4%. The experimental absorption was 97.1% (simulated absorption was 98%) and the emissivity was from 13% to 20% (simulated emissivity was 8% to 26%) as the temperature increased from 400 to 800 °C. Full article
(This article belongs to the Special Issue Design, Manufacturing and Measurement of Optical Film Coatings)
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Open AccessArticle
The Fabrication of a UV Notch Filter by Using Solid State Diffusion
Coatings 2019, 9(3), 208; https://doi.org/10.3390/coatings9030208
Received: 26 February 2019 / Revised: 15 March 2019 / Accepted: 20 March 2019 / Published: 23 March 2019
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Abstract
One of the methods used to obtain notch filters involves one or several gradient index layers. In this method, the indices are decreased and then increased step by step to create a sinusoidal-like gradient layer. This paper reports a sinusoidal-like gradient layer fabrication [...] Read more.
One of the methods used to obtain notch filters involves one or several gradient index layers. In this method, the indices are decreased and then increased step by step to create a sinusoidal-like gradient layer. This paper reports a sinusoidal-like gradient layer fabrication method based on solid state diffusion. Al2O3/MgO/Al2O3 (AMA) was deposited by electron beam evaporation and then post-annealed at 800 °C for 4 h. Through inner diffusion, the MgO layers became a low refractive index material with a porous structure (the average refractive index was 1.55) such that the MgAl2O4 spinel was formed as an inhomogeneous layer with an average refractive index of 1.69. This allowed simply using a structured multilayer, (Al2O3/MgO)8 Al2O3, and post-annealing to form a sinusoidal-like gradient layer for a UV notch filter. Full article
(This article belongs to the Special Issue Design, Manufacturing and Measurement of Optical Film Coatings)
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Open AccessArticle
Comparison of the Optical and Electrical Properties of Al-Doped ZnO Films Using a Lorentz Model
Received: 29 October 2018 / Revised: 9 December 2018 / Accepted: 17 December 2018 / Published: 21 December 2018
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Abstract
In this research, zinc oxide (ZnO) films are doped with various amounts of Al dopants, from 0 to 13 at.%, using ion-beam co-sputtering for Zn and Al metallic targets at room temperature. The Al-doped ZnO (AZO) films appear to have lower transmittances in [...] Read more.
In this research, zinc oxide (ZnO) films are doped with various amounts of Al dopants, from 0 to 13 at.%, using ion-beam co-sputtering for Zn and Al metallic targets at room temperature. The Al-doped ZnO (AZO) films appear to have lower transmittances in the UV and near-IR ranges. The electrical and optical properties of each film are successfully analyzed by using the spectroscopic ellipsometry of two Lorentz oscillators for the two lower transmittances. The optimal AZO film is deposited with an Al-dopant of 1.5 at.% at an oxygen partial pressure of 0.12 mTorr; it has the smallest resistivity of 7.8 × 10−4 Ω cm and high transmittance of > 80% in the visible regions. The free carrier concentration and mobility evaluated using ellipsometry are different from those measured using the Hall effect. This phenomenon was the result of the grain boundary scattering due to the small ~20-nm grain size of the AZO film used in this study. Full article
(This article belongs to the Special Issue Design, Manufacturing and Measurement of Optical Film Coatings)
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Open AccessFeature PaperArticle
Extinction Properties of Obliquely Deposited TiN Nanorod Arrays
Coatings 2018, 8(12), 465; https://doi.org/10.3390/coatings8120465
Received: 3 November 2018 / Revised: 11 December 2018 / Accepted: 13 December 2018 / Published: 14 December 2018
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Abstract
Plasmonic titanium nitride (TiN) nanorod arrays (NRA) were fabricated by glancing angle deposition in a DC magnetron reactive sputtering system. The morphology of the TiN NRA was varied by collimating the vapor flux. The transmittance, reflectance, and extinctance of slanted TiN nanorods with [...] Read more.
Plasmonic titanium nitride (TiN) nanorod arrays (NRA) were fabricated by glancing angle deposition in a DC magnetron reactive sputtering system. The morphology of the TiN NRA was varied by collimating the vapor flux. The transmittance, reflectance, and extinctance of slanted TiN nanorods with different lengths as functions of wavelength and angle of incidence were measured and analyzed. The extinction peaks in the spectra reveal the transverse and longitudinal plasmonic modes of TiN NRA upon excitation by s-polarized and p-polarized light, respectively. The near-field simulation was performed to elucidate localized field enhancements that correspond to high extinction. The extension of the high extinction band with an increasing length of the nanorods results in broadband and wide-angle light extinction for a TiN NRA with a thickness greater than 426 nm. Full article
(This article belongs to the Special Issue Design, Manufacturing and Measurement of Optical Film Coatings)
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Open AccessArticle
Design and Fabrication of a Narrow Bandpass Filter with Low Dependence on Angle of Incidence
Coatings 2018, 8(7), 231; https://doi.org/10.3390/coatings8070231
Received: 31 May 2018 / Revised: 23 June 2018 / Accepted: 27 June 2018 / Published: 29 June 2018
Cited by 1 | PDF Full-text (2554 KB) | HTML Full-text | XML Full-text
Abstract
A multilayer narrow bandpass filter that consists of silver and silicon thin films is designed using the admittance tracing method. Owing to the low loss of silicon in the infrared range, the peak transmittance at a wavelength of 950 nm exceeds 85%. To [...] Read more.
A multilayer narrow bandpass filter that consists of silver and silicon thin films is designed using the admittance tracing method. Owing to the low loss of silicon in the infrared range, the peak transmittance at a wavelength of 950 nm exceeds 85%. To eliminate the sidebands that are adjacent to the passband, a compact four-layered structure is proposed to generate an angle-insensitive spectrum. In fabrication, a silver-silicon multilayer is deposited to approach the design. Full article
(This article belongs to the Special Issue Design, Manufacturing and Measurement of Optical Film Coatings)
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