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1
Content available Effects of Microwave Sintering on Properties and Microstructure of Ferromanganese Alloy Powders
Lei L., Libo Z., Linqing D., Hongbo Z., Guo C., Jinhui P., Qin G.
Archives of Metallurgy and Materials
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2018
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Vol. 63, iss. 2
547--553
EN
Microwave sintering process was employed to agglomerate ferromanganese alloy powders. The effects of sintering temperature, holding time and particle size composition on the properties and microstructure of sintering products were investigated. The results was shown that increasing sintering temperature or holding time appropriately is beneficial to increase the compressive strength and volume density. SEM and EDAX analysis shows that the liquid phase formed below the melting point in the sintering process, which leads to densification. XRD patterns indicate that the main reaction during microwave sintering is the decarbonization and carburization of iron carbide phase. The experiment demonstrate that the optimum microwave sintering process condition is 1150°C, 10 min and 50% content of the powders with the size of –75 μm.
2
Content available Highly-efficient three-port output by metal-mirror-based grating
Li H., Wang B., Shu W., Chen L., Lei L., Zhou J.
Optica Applicata
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2016
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Vol. 46, nr 1
87--92
EN
A highly-efficient three-port output of metal-mirror-based grating is proposed in this paper. The metal-mirror-based grating can function as a beam splitter which can diffract the normal incident wave into the 0th and the +/- 1st orders for both TE and TM polarizations with the usual duty cycle of 0.5. The analysis of the grating parameters can be optimized by rigorous coupled-wave analysis. The high efficiency for TE and TM polarizations shall be realized. By means of the numerical simulation, the depth and connecting layer thickness of grating can be accurately calculated. The efficiency of per port is near 33.3%, so the novel three-port output grating with a connecting layer would be an excellent optical element.
3
Content available 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.
4
Content available Polarization-independent metal-dielectric grating with improved bandwidth
Wang B, Li H, Shu W, Li W, Li C, Lei L, Zhou J
Optica Applicata
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2015
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Vol. 45, nr 1
71--77
EN
A polarization-independent reflective grating with improved bandwidth is presented based on the mixed metal-dielectric grating. The novel grating is composed of the substrate, the metal slab, two dielectric layers, and the covering layer. The grating parameters are optimized for the special duty cycle of 0.6 at an incident wavelength of 1550 nm used in dense wavelength division multiplexing (DWDM). With the designed grating, high efficiency can be diffracted into the reflective –1st order for both TE and TM polarizations, where the polarization-independence is exhibited. Most importantly, the efficiency of more than 90% can be achieved within the incident wavelength bandwidth of 1262–1686 nm, where the bandwidth is improved greatly compared with the reported surface-relief single-layer grating. The reflective grating can have advantages of high efficiency, polarization-independence, and wide bandwidth, which should be useful for DWDM applications.
5
Content available 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.
6
Content available 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.
7
Content available remote 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.
8
Content available remote Reflective diffraction with high efficiency and beam splitter by metal-mirror-based grating
Wang B., Lei L., Chen L., Zhou J.
Optica Applicata
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2012
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Vol. 42, nr 3
473-479
EN
It is interesting and desirable to achieve two functions of high efficiency and two-port output with one reflective grating, which is not easy to acquire by multilayer coatings. We describe the reflective high efficiency element and the two-port beam splitter by the metal-mirror-based grating. By modal method, the design guideline is proposed according to the two-beam interference of the excited modes by incident TE and TM polarizations. Using rigorous coupled-wave analysis (RCWA), accurate grating parameters are optimized by numerical calculation. This indicates that wideband property can be achieved for such a reflective dual-function grating. Furthermore, the element can also be used for beam splitting for TE polarization with the pre-determined angle of incidence. With merits of wideband and so many functions, the reflective elements presented should be useful in a variety of optical systems.
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