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1

Three-port beam splitter based on a sandwiched grating with an improved aspect ratio

Shu W, Wang B, Li H, Li W, Chen L., Lei L., Zhou J.

Optica Applicata

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2015

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Vol. 45, nr 3

279--284

EN

In this paper, a fused-silica transmission grating used as a three-port beam splitter is designed by using the rigorous coupled-wave analysis, which is based on the sandwiched grating structure at the wavelength of 800 nm under normal incidence. Firstly, it is feasible to realize such a grating with the prescribed grating duty cycle and grating period. Next, high efficiency can be also achieved for both TE and TM polarizations. Moreover, the aspect ratio of the grating depth to the ridge width can be improved, which is significant for practical applications. At last, the three-port beam splitter is designed with a covering layer on the surface, which can extend its life service.

2

Polarization-selective beam splitter by a sandwiched grating

Wang B, Chen L, Lei L, Zhou J

Optica Applicata

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2013

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Vol. 43, nr 2

s. 229-236

EN

We describe a polarization-selective beam splitter by a sandwiched grating, which can fulfill the high efficiency element for TE polarization and the two-port output for TM polarization. The modal method and the rigorous coupled-wave analysis (RCWA) are employed together to optimize the polarization-selective beam splitter. According to the modal method, the grating duty cycle and period are discussed to analyze the physical mechanism of such a dual-function element. Using RCWA, grating depth and thickness of the covering layer are accurately optimized to design such a polarization-selective beam splitter. With the optimized grating duty cycle, period, depth and covering layer thickness, TE polarization can be mainly diffracted in the –1st order and two-port output can be achieved for TM polarization in the 0th and the –1st orders. The polarization-selective beam splitter should be a useful element in a variety of applications with advantages of high efficiency, wideband property, and dual functions based on a sandwich grating.

3

Binary-phase metal-based sandwiched grating with high efficiency

Wang B., Chen L., Lei L., Zhou J.

Optica Applicata

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2013

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Vol. 43, nr 3

607--613

EN

We describe a novel high efficiency element based on a binary-phase metal-based sandwiched grating, where the binary grating is covered by a dielectric layer and connected by a metal slab on the fused-silica substrate. The modal method is used to optimize the grating duty cycle and period to analyze the feasibility to achieve high efficiency for TE and TM polarizations by effective indices of the modes excited in the grating region. Rigorous coupled-wave analysis (RCWA) is employed to optimize the grating depth and to cover the layer thickness accurately by numerical calculations. It is not easy for the conventional binary grating with a usual duty cycle to achieve high efficiency in the –1st order for TM polarization. For the binary-phase metal-based sandwiched grating, high efficiency can be diffracted into the –1st order for not only TE polarization but also TM polarization. Moreover, the wide fabrication tolerance, the wideband property and the flat surface of easy cleaning should be significant for practical applications in a variety of optical systems.

4

Sandwiched grating for high efficiency with wide bandwidth and polarization independence

Wang B, Lei L, Chen L, Zhou J

Optica Applicata

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2012

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Vol. 42, nr 4

743--749

EN

We describe novel sandwiched grating for high efficiency with polarization independence. The grating parameters can be optimized based on modal method and rigorous coupled-wave analysis (RCWA). According to modal method, grating period and duty cycle are prescribed for polarization independence by excited modes with different effective indices. Using RCWA, accurate grating depth and covering layer thickness are optimized by numerical calculation. The sandwiched grating can show high efficiency for both TE and TM polarizations with the optimized grating period, duty cycle, depth, and covering layer thickness. Most importantly, wideband property can be obtained for operation around the central wavelength of 800 nm. The presented novel sandwiched grating can have merits of high efficiency, polarization independence, and wideband property, which should be of great significance for numerous applications.