Jui-Hung Liu

A Fiber Splicing-Plane-Inspection Technique Using Lens–Fiber Interference for the Cascaded Fiber Fabrication

In this paper, a novel inspection technique for the cascaded fiber fabrication is proposed to improve the coupling performance of such fibers. Instead of using a direct-monitoring method, an indirect technique with the help of the ray tracing and the lens-fiber interference is used. By calculating the optical-path length of the light rays passing through the fiber, the interference fringes and light intensity can be counted. Then, the splicing plane of the cascaded fiber can be determined by observing the difference between the two fiber sections. Simulations and experiments have been performed to find the splicing plane. Finally, the accuracy of fabrication can be improved from 10 to about 1 mum; thus, the coupling loss due to the fabrication process can be reduced

Feedback linearization control for a wind turbine driven by a variable-speed pump-controlled hydraulic servo system

The study aims to develop a feedback linearization controller applying to a novel pitch control system for a large wind turbine driven by a variable-speed pump-controlled hydraulic servo system. The variable-speed pump-controlled hydraulic servo system is composed of an AC servo motor, a constant displacement hydraulic piston pump two differential hydraulic cylinders and hydraulic circuits. Finally, the mathematic model is verified by the experimental test rig and the tracking performance in both 5th order polynomial and sinusoidal path are implemented by the proposed feedback linearization controller.

Corrections to “A Fiber Splicing-Plane-Inspection Technique Using Lens–Fiber Interference for the Cascaded Fiber Fabrication”

In this paper, a novel inspection technique for the cascaded fiber fabrication is proposed to improve the coupling performance of such fibers. Instead of using a direct-monitoring method, an indirect technique with the help of the ray tracing and the lens-fiber interference is used. By calculating the optical-path length of the light rays passing through the fiber, the interference fringes and light intensity can be counted. Then, the splicing plane of the cascaded fiber can be determined by observing the difference between the two fiber sections. Simulations and experiments have been performed to find the splicing plane. Finally, the accuracy of fabrication can be improved from 10 to about 1 mum; thus, the coupling loss due to the fabrication process can be reduced

Automation of active quadrangular pyramid-shaped fiber endface polishing method

A high-power laser diode (LD) has an elliptical mode field at the endface of its laser diodes. A mode field mismatch between the high-power LD and single-mode fibers (SMFs) results in low coupling efficiency. Accordingly, various methods for coupling between the LD with the higher aspect ratio and SMFs have been employed. Among these approaches, the quadrangular pyramid-shaped fiber endface (QPSFE), which has the capability to control both axial curvatures, can easily match the far field of the high-power LD. However, a QPSFE, which was fabricated by polishing techniques, is hard to employ because of the special shape involved and the need for high precision. This paper presents a novel method for automating QPSFE polishing based on a thorough system analysis and using an online image inspection system. The system successfully supported automatic polishing with an encouraged fiber tip offset that ensures high coupling efficiency. Such an automatic polishing system can also be applied to any other type of fiber endface

A Control Strategy for Force Sensing Mechanism in Bare-fiber Polishing

A bare fiber polishing control strategy and force sensing mechanism is proposed and implemented to improve the fiber polishing performance used in optical communication. Through the analysis of the force and the problems encountered during the polishing process, this study has successfully measured the required force with the encouraged precision.