A new scheme of asymmetric elliptic-cone-shaped microlens (AECSM) employing a single-step fabrication technique for efficient coupling between the high-power 980-nm laser diodes and the single-mode fibers is proposed. The AECSMs are fabricated by asymmetrically shaping the fiber during the single-step grinding process and elliptically lensing the fiber tip during the fusing process. A maximum coupling efficiency of 85% and a high-average coupling efficiency of 71% have been demonstrated for a 980-nm laser diode with a high aspect ratio of 5. In comparison with the previous works on asymmetric fiber microlenses fabricated by the multi-step processes with complicated fabrication, the advantages of the AECSM structure for achieving high coupling are a single-step fabrication, a reproducible process, and a high-yield output. Therefore, this AECSM can form different aspect ratios of asymmetric elliptical microlenses to match the far field of the high-power diode lasers that is suitable for use in commercial high-power pump laser modules.

A new scheme of optical fibers with different types of end-faces by applying different types of periodical variable torques to control the polishing pressure is proposed and fabricated. Two types of mechanisms, mechanical torque and electrical torque controls, are developed to generate different types of periodical variable torques. The mechanical torque control type is mainly designed for fabricating an elliptical-cone-shaped fiber end-face that can be used in efficient coupling between a laser diode and fiber with a coupling efficiency up to 83% (Lu et al 2007 Opt. Express 15 1434). The electrical torque control type is even more versatile for fabricating optical fibers or micro-probes with polygon pyramid end-faces that may have other potential applications, such as various kinds of micro-indenters. Both types of fiber end-faces can deliver satisfactory results with single-step fabrication, a high fabrication yield and sufficient optical coupling efficiency.

A motor core is formed by stacking iron sheets on top of each other. Traditionally, there are two stacking methods, riveting and welding, but these two methods will increase iron loss and reduce usage efficiency. The use of resin is the current developmental trend in the technology used to join iron sheets, which has advantages including lowering iron loss, smoothing magnetic circuits, and generating higher rigidity. The flow behavior of resin in gluing technology is very important because it affects the dipping of iron sheets and the stacking of iron sheets with resin. In this study, a set of analytical processes is proposed to predict the flow behavior of resin through the use of computer-aided engineering (CAE) tools. The research results are compared with the experimental results to verify the accuracy of the CAE tools in predicting resin flow. CAE tools can be used to predict results, modify modules for possible defects, and reduce the time and costs associated with experiments. The obtained simulation results showed that the filling trend was the same as that for the experimental results, where the error between the simulation results for the final dipping process and the target value was 0.6%. In addition, the position of air traps is also simulated in the dipping process.

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