Wide Bandwidth Silicon Nitride Strip-Loaded Grating Coupler on Lithium Niobate Thin Film

In this research, a vertical silicon nitride strip-loaded grating coupler on lithium niobate thin film was proposed, designed, and simulated. In order to improve the coupling efficiency and bandwidth, the parameters such as the SiO2 cladding layer thickness, grating period, duty cycle, fiber position, and fiber angle were optimized and analyzed. The alignment tolerances of the grating coupler parameters were also calculated. The maximum coupling efficiency and the −3 dB bandwidth were optimized to 33.5% and 113 nm, respectively. In addition, the grating coupler exhibited a high alignment tolerance.

LAMOST Fiber Positioning Unit Detection Based on Deep Learning

The double revolving fiber positioning unit (FPU) is one of the key technologies of The Large Sky Area Multi-Object Fiber Spectroscope Telescope (LAMOST). The positioning accuracy of the computer controlled FPU depends on robot accuracy as well as the initial parameters of FPU. These initial parameters may deteriorate with time when FPU is running in non-supervision mode, which would lead to bad fiber position accuracy and further efficiency degradation in the subsequent surveys. In this paper, we present an algorithm based on deep learning to detect the FPU’s initial angle using the front illuminated image of LAMOST focal plane. Preliminary test results show that the detection accuracy of the FPU initial angle is better than 2.°5, which is good enough to distinguish those obvious bad FPUs. Our results are further well verified by direct measurement of fiber position from the back illuminated image and the correlation analysis of the spectral flux in LAMOST survey data.

Grating Coupler Design for Vertical Light Coupling in Silicon Thin Films on Lithium Niobate

In this paper we provide a design for a vertical grating coupler for a silicon thin film on lithium niobate. The parameters-such as the cladding layer thickness of lithium niobate, fiber position, fiber angle, grating period, and duty cycle are analyzed and optimized to reduce the mode mismatch loss and the internal reflections. The alignment tolerances, for the grating coupler parameters, are also simulated and evaluated. We determine that our simulated grating coupler exhibits high efficiency, enhanced light coupling, and high alignment tolerance.

Effect of glass fiber non-dental’s length and position on the flexural strength of FRC

Glass fiber non-dental has a similar composition to E-glass fiber dental that commonly used as fiber reinforced composite (FRC) materials in resin bonded prosthesis. Fiber effectiveness can be determined by the length and the position. The aim of this study was to examine the effect of glass fiber non dental’s length and position on the flexural strength of FRC in resin bonded prosthesis. This study has been done used 36 FRC samples with beam shaped (15 mm x 2 mm x 2 mm). Fiber reinforced composite samples were consisted of 9 groups (a combination between length: 4 mm, 6 mm, and 12 mm and position: compression, neutral, tension zone). The flexural strength was tested by universal testing machine and statistically analyzed using two-way ANOVA (p<0.05). The result showed that the lowest (compression, 4 mm) and the highest (tension, 12 mm) flexural strength were 104.30 ± 13.90 MPa and 166.18 ± 8.59 MPa. The two-way ANOVA test showed that variation of position, length, and interaction between placement-length had a significant effect on the flexural strength (p<0.05). The conclusion of this study was fiber position on compression zone with 4 mm length had the lowest flexural strength. In addition, fiber position on tension zone with 12 mm length had the highest flexural strength.

Effects of silkworm fiber position on flexural and compressive properties of silk fiber-reinforced composites

Background: Fiber-reinforced composites represent a combination of fiber-reinforced composite materials. The availability of fiber within dentistry in Indonesia is limited and, therefore, requires lengthy advance ordering. The increasing use of fiber derived from natural materials, such as silk, is of greater concern due to its considerable mechanical strength, biocompatibility and wider availability. The application of fiber will increase the mechanical strength of fiber-reinforced composites, including both flexural and compression strength. One factor affecting the mechanical strength of fiber is the laying of fiber or fiber position. Purpose: The purpose of this research is to establish the influence of silkworm fiber position on both the flexural and compression strength of silk fiber-reinforced composites. Methods: Flexural strength and compression strength tests using a universal testing machine involved the division of the research population into three treatment groups: compression side, neutral side and tension side. Results: The results of data analysis indicated that the tension side group possessed the highest flexural strength (121.42 MPa), while the compression side group demonstrated the highest compression strength (337.65 MPa). A one-way ANOVA analysis test produced a significant result of p = 0.000 (<0.05) both for silkworm fiber position effect and compression strength of silk fiber reinforced composites. Conclusion: The position of silkworm fiber will affect its flexural strength as well as that of the compression of silk fiber-reinforced composites.

Effect of Plasma and Fiber Position on Flexural Properties of a Polyethylene Fiber-Reinforced Composite

The aim of this study was to evaluate the effect of plasma treatment using argon and oxygen gases, combined with fiber position on flexural properties of a fiber-reinforced composite. Eleven groups were evaluated, a non-reinforced control group and 10 groups reinforced with InFibra, a woven polyethylene fiber, varying according to the plasma treatment and fiber position. The samples were prepared using a stainless steel two-piece matrix. The three point bending test was performed in an EMIC testing machine. Flexural strength (FS) and flexural deflection (FD) were calculated from initial (IF) and final (FF) failure. Data were evaluated statistically using Kruskal-Wallis and Mann-Whitney tests (p<0.05). For IF, in all groups with fibers placed on the base, the FS and FD values were significantly higher than those positioned away from the base. The highest value of FS was obtained in the group treated with O 3 min (296.2 MPa) and the highest value of FD was obtained in the group treated with 1 min (0.109 mm). For FF the FS and FD values obtained for the groups with fibers positioned away from the base were similar or higher than those placed on the base. The highest FS value was obtained in the group treated with 1 min (317.5 MPa) and the highest FD value was obtained in the group treated with O 3 min (0.177 mm). Plasma treatment influenced FS and FD. Fiber position and plasma treatment affected the flexural properties of a fiber-reinforced composite.