The optimization of sawtooth gratings using RCWA and its fabrication on a slanted silicon substrate by fast atom beam etching

Advances in Optical Technologies

2014

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This paper presents a fast and rigorous design method for grating-based metal-free polarizing filter applications using two-step hybrid optimization techniques. Grating structures utilizing the total internal reflection in a lamellar configuration were used to achieve metal-free solution, which is a key technology in the chirped pulse amplification for high power laser system. Here two polarizing filters were designed: polarization sensitive and polarization insensitive. Those polarization performances were characterized by the rigorous coupled-wave analysis (RCWA), and the design parameters of grating structures, pitch, depth, and filling factor were optimized by two-step hybrid optimization procedure because the diffraction characteristics of grating-based polarizing filters are highly sensitive to small changes in design parameters. The Taguchi method is incorporated into selection process in the genetic algorithm, which indicates that the Taguchi method optimizes the design parameters in a coarse manner, and then, coarsely optimized parameters are finely optimized using the genetic algorithm. Therefore the proposed method could solve global numerical optimization problems with continuous variables. The proposed two-step hybrid optimization algorithm could effectively optimize the grating structures for the purpose of polarization filter applications, and the optimized grating structures could selectively filter the incident light up to 99.8% as to TE or TM waves.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Total Internal Reflection-Based High Efficiency Grating Design for a Metal-Free Polarizing Filter Applications Using Hybrid Optimization Procedure

Advances in Optical Technologies

2014

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“…On the other hand, 2 International Journal of Manufacturing Engineering ultraprecision machining-based fabrication methods rely on more complicated mechanisms depending on the degree of the size effect due to small ratio of depth of cut to the tool edge radius. In addition, both MEMS-based and ultraprecision machining-based machining methods are expensive [11,14]. An evident disadvantage of using a lens with grooves is the possibility of losing light due to incidence on the draft facet.…”

Section: Introductionmentioning

confidence: 99%

Design and Fabrication of Diffractive Light-Collecting Microoptical Device with 1D and 2D Lamellar Grating Structures

International Journal of Manufacturing Engineering

2014

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This paper presents the optimal design method of diffractive light-collecting microoptical device and its fabrication method by E-beam lithography, fast atom beam etching, and hot-embossing processes. The light-collecting device proposed in the paper is comprised of 9 (3 × 3) blocks of optical elements: 4 blocks of 1D lamellar grating structures, 4 blocks of 2D lamellar grating structures, and a single block of nonpatterned element at the center, which acts for lens to be able to collect the diffracted and transmitted lights from the lamellar grating structures into the focus area. The overall size of the light-collecting device is 300 × 300 μm2, and the size of each block was practically designed as 100 × 100 μm2. The performance of 1D and 2D lamellar grating structures was characterized in terms of diffraction efficiency and diffraction angle using a rigorous coupled-wave analysis (RCWA) method, and those geometric parameters, depth, pitch, and orientation, were optimized to achieve a high light-collecting efficiency. The master molds for the optimized structures were fabricated on Si substrate by E-beam lithography and fast atom beam etching processes. The 100 μm thick patterned polymethyl methacrylate (PMMA) film was then replicated by a hot-embossing process. As a result, the patterned PMMA film collected 63.0% more incident light than a nonpatterned one.

“…SRGs play an important role in diffractive optical elements (DOEs) such as spectrometer, monochromator and multiple imaging devices [1][2][3][4][5][6]. Keeping …”

Section: Introductionmentioning

confidence: 99%

“…3, respectively.This measured peak-to-valley depth was slightly less than the designed one due to the edge-rounding effect occurring in stylus-profiling method. Furthermore, it has been known that the large blazed angle just as the fabricated blazed gratings in this paper may cause errors at steep blazed facets and it results in change in diffraction angle and efficiency[2,5] …”

mentioning

confidence: 96%

Fast atom beam-based fabrication of high-efficienct blazed grating using slanting angle control of a substrate

Hane

2010 International Conference on Optical MEMS and Nanophotonics

2010

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This paper presents electromagnetic analysis of Sibased small period blazed reflection gratings for a period of 0.6 -1.5 in terms of the rigorous coupled wave analysis (RCWA) and its fabrication using fast atom beam (FAB) etching method. The optimized blazed gratings were successfully fabricated on a slanted silicon substrate by FAB etching method, and diffraction efficiencies (DE) for four kinds of gratings were evaluated from optical testing and these results showed good agreement with these theoretical values, respectively.