Browsing by Author "Ting, Chia-Jen"

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Antireflection subwavelength structures analyzed by using the finite difference time domain method
(2009)
Ting, Chia-Jen
;
Chen, Chi-Feng
;
Chou, C. P.
;
機械工程學系
;
Department of Mechanical Engineering
Antireflection subwavelength structures (ASSs) are analyzed by using the finite difference time domain (FDTD) method in the visible light spectrum. Low reflectance can be obtained by both the conical and pyramidal shapes over a broadband range. Comparing the reflectance of different structure shapes and aspect ratios by the FDTD method, it shows that the antireflection efficiencies of the pyramidal structures are better than that of the conical structures when the aspect ratio is up to 0.8. It is found that, for the conical structure surface, the average transmittance increases gradually with the aspect ratio and the average transmittance is about 99.6% with the aspect ratio of 2.0. However, for the pyramidal structure with the aspect ratio ranging from 1.0 to 2.0, the average transmittance is up to 99.7%. (C) 2008 Elsevier GmbH. All rights reserved.
Experimental study of a silver layer on an antireflection subwavelength-structured surface
(2008-07-01)
Ting, Chia-Jen
;
Chen, Chi-Feng
;
Chou, C. P.
;
機械工程學系
;
Department of Mechanical Engineering
The optical characteristics of a silver layer deposited on an antireflection subwavelength-structured surface are investigated. The experimental results of the reflectance and the transmittance of several different thicknesses of silver layer on the subwavelength-structured surface are carried out. A subwavelength structure with the spatial period and diameter of about 230 nm and height of about 150 nm on polyethylene terphthalate film is fabricated by microreplication process. It is shown that such an element with the suitable silver layer deposited on an antireflection subwavelength-structured surface has high transmittance and low glare in the visible spectral range and high reflectance in the infrared range. Obviously, the optical film with silver layer can not only obtain the high performance of heat insulation but also give an application in automobile and house windows.
Fabrication of an antireflective polymer optical film with subwavelength structures using a roll-to-roll micro-replication process
(2008-07-01)
Ting, Chia-Jen
;
Chang, Fuh-Yu
;
Chen, Chi-Feng
;
Chou, C. P.
;
機械工程學系
An antireflective optical film with subwavelength structures replicated by use of a roll-to-roll micro-replication process (RMRP) is investigated. Firstly, a single layer of a nanostructure on a polymer film is designed for an antireflection purpose by the finite difference time domain method in the visible light spectrum. Structures of a conical cylinder array, with spatial period of 400 nm, diameter of 200 nm and height of 350 nm, are numerically obtained. Then, such structures are fabricated by RMRP combining originated structure fabrication realized by deep ultra-violet lithography and dry etching, Ni mold electroplating and replication by using the roll-to-roll process imprinting into the flexible polyethylene terephthalate substrate. A nanostructure roller mold bonded with Ni molds has been successfully fabricated and coated with the self-assembly monolayer process for the purpose of fabricating an anti-adhesion film and improving the lifetime of the Ni molds. The duplicated nanostructure films show a good optical quality of antireflection (AR <= 2.45% in a 400-700 nm spectral range) and are in good agreement with the theoretical predictions. The experimental results show that the developed process is a promising and cost-effective method for the continuous duplication of flexible devices with nano-scaled feature sizes used in nanophotonics by RMRP.
Low cost fabrication of the large-area anti-reflection films from polymer by nanoimprint/hot-embossing technology
(2008-05-21)
Ting, Chia-Jen
;
Huang, Meng-Chi
;
Tsai, Hung-Yin
;
Chou, Chang-Pin
;
Fu, Chien-Chung
In this paper, we present a low cost approach to produce large-area polymer sheets with sub-wavelength nanostructures. The fabricated polymer films would have great potentials to attach to optical or solar-cell-related consumer products when anti-reflection/anti-glaring is mandatory. We employed a special electron cyclotron resonance (ECR) plasma process to fabricate the SWSs with large area directly on silicon substrates. Homogeneously distributed nanotips on the full 4 inch silicon substrate were fabricated by using gas mixtures of silane, methane, argon and hydrogen. An Ni-Co metal mold with a hardness of 550 HV was produced through the replication of the Si mold by electroplating. Afterwards, the molding process was applied to manufacture the nanostructures in PMMA plates in large volume. The nanostructures in PMMA plates with aspect ratios of 4 and diameters of 150 nm were fabricated. The fabricated PMMA sheets could generate the gradient of the refractive indices, absorb the light and greatly reduce the reflectivity. Compared with the PMMA without SWSs, the reflectivity of PMMA with SWSs decreased dramatically from 4.25% to 0.5% at the wavelength of light from 400 to 800 nm.
Sapphire surface patterning using femtosecond laser micromachining
(2012-11-01)
Chang, Cho-Wei
;
Chen, Chien-Yu
;
Chang, Tien-Li
;
Ting, Chia-Jen
;
Wang, Chien-Ping
This study presents an alternative method for micron-resolution patterning of a sapphire surface utilizing the characteristic of an ultra-short pulse (10(-15) s) from ytterbium (Yb) femtosecond laser (FS-laser) irradiation. Conventional processes often involve several steps, such as wet chemical or dry etching, for surface structuring of sapphire. In this study, two-dimensional array patterns on the sapphire surface with an area of 5x5 mm(2) and a depth of 1.2 +/- 0.1 mu m can be directly and easily fabricated by a single step of the FS-laser process, which involves 350-fs laser pulses with a wavelength of 517 nm at a repetition rate of 100 kHz. The measured ablation depths on the sapphire surface display that the proposed process can be under well-controlled conditions. Based on the design changes for being quickly implemented in the micromachining process, a FS laser can be a promising and competitive tool for patterning sapphire with an acceptable quality for industrial usage.
Study of Metals by Femtosecond Laser Processing for Electro-Optics Applications
(2012)
Chang, Cho-Wei
;
Chang, Tien-Li
;
Tsai, Ting-Kai
;
Ting, Chia-Jen
;
Wang, Chien-Ping
Femtosecond laser (FS-laser) microstructuring of metals has become a promising tool because of its non-contact nature, which allows the micromachining and direct processing of materials with a minimized volume of heat-affected zone for electro-optics applications such as light emitting diodes (LED) and solar photovoltaic (PV) lighting. This study presents ultra-short pulse (10(-15) sec) FS-laser processing. Through integrating the laser source, optical system and dynamic control modules, the materials of metals with micro-scale or nano-scale structures can be fabricated. In traditional processing such as semiconductor processing, development, exposure and etching necessitate expensive equipment and time-consuming tasks. With FS-laser processing, high-precision patterns are obtained, which will be a great benefit to keeping costs down. In this study, the wavelengths of FS-laser ablation are employed using visible and infrared light. To make a breakthrough in electro-optics processes, the CIGS thin-film of solar cells in metal process can be easily produced by the FS-laser. The ablation speed of the FS-laser for thin film layer CIGS solar cells can reach 2000 mm/s which is faster than the current Nd:YAG laser machine (similar to 1000 mm/s). On the other hand, the minimum size of metal lines can be controlled to a value that is lower than 40 mu m. Furthermore, green energy can be effectively developed for the future.
Subwavelength structures for broadband antireflection application
(2009-02-01)
Ting, Chia-Jen
;
Chen, Chi-Feng
;
Chou, C. P.
;
機械工程學系
;
Department of Mechanical Engineering
The subwavelength structures are designed and fabricated for broadband antireflection application. Under target of zero reflectivity, the parameters of periodic 2-D continuous conical structures are analyzed by the finite-difference time-domain (FDTD) method. The corresponding conical structures are obtained with spatial period of 350 nm and structure height of 300 nm, respectively. The 2-D continuous conical structured surface is fabricated by micro-replication process combining with the originated structure fabrication realized by interference lithography, Ni mold electroplation and replication by using UV imprinting into plastics. The average reflectances of the simulation and replicated polymer prototype are about 0.50% and 0.54% within the spectral ranges of 400-650 nm, respectively. In a word, the subwavelength structured surface with low reflection is developed and proved to be highly consistent with the simulation results. (C) 2008 Elsevier B.V. All rights reserved.