Yu-Da Liu

Asymmetric elliptic-cone-shaped microlens for efficient coupling to high-power laser diodes

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.

New Scheme of Double-Variable-Curvature Microlens for Efficient Coupling High-Power Lasers to Single-Mode Fibers

A new scheme of a double-variable-curvature microlens (DVCM) employing a single-step grinding technique with fully automated fabrication for efficient coupling between high-power 980-nm laser diodes and single-mode fibers is proposed and demonstrated. The grinded fiber endface exhibited a double-variable curvature in the major axis, and was clearly observed for both major and minor axes after slight fusion polish. The perfect aspherical shape of the DVCM results in less grinding offset of 0.2 μm and better curvature radii control that leads to high average coupling efficiency of 83%. This clearly indicates that the performance of the DVCM can achieve high average coupling efficiency better than any other grinding techniques to form asymmetric microlenses. The versatility in double-variable-curvature design, fully automated fabrication, and the excellent performance of aspherical microlens makes the proposed DVCM extremely attractive for use in many lightwave interconnection applications.

A new scheme of fiber end-face fabrication employing a variable torque technique

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.

Online Postweld Shift Measurement of Butterfly-Type Laser Module Employing High-Resolution Capacitance Displacement Measurement System

A quantitative postweld shift (PWS) correction employing a high-resolution capacitance displacement measurement system (CDMS) in laser-welded butterfly-type laser module package is demonstrated. The CDMS has a 25.4-nm resolution and enables precise online measurement of the PWS in both the horizontal and vertical directions. By applying a mechanical adjustment to compensate for the magnitude and direction of the PWS measured online by the CDMS, the results show that the fiber tip can be realigned back closer to the original optimum coupling positions. A relative coupling efficiency of the laser modules can be regained up to an average of 88% by using the CDMS. In comparison with the previous studies on the quantitative PWS compensation in laser-welded butterfly-type laser module packages, the advantages of using this novel CDMS are the high-resolution and the online measurements of the PWS in laser-welded butterfly-type laser module packages. Through an in-depth study on the precise online measurement of the PWS employing high-resolution CDMS, it is now possible to fabricate high-yield butterfly-type laser modules for use in lightwave transmission systems and utilization of many other high-yield and low-cost laser-welded photonics module packages.

A novel scheme of double-variable curvature microlens for efficient coupling high-power laser diodes into fibers

A new scheme of a double-variable curvature microlens (DVCM) grinding technique for efficient coupling between the high-power 980-nm laser diodes and single mode fibers (SMFs) is proposed. The DVCMs has high average coupling efficiency of 54%. In comparison with the previous works of microlens fabricated by grinding and polishing technique, the advantages of DVCMs are a single-step without fused process, reproducible fabrication, less process time, and high yield. Furthermore, the proposed technique enables to offer variety designed microlenses for efficient coupling between laser diodes and SMFs used in interconnections.

Online postweld shift measurement of butterfly-type laser module using a 25.4-nm resolution measurement system

A quantitative measurement using a 25.4-nm resolution system to online measure the postweld shift in laser-welded butterfly-type laser module package is demonstrated. The relative coupling efficiency can be regained up to an average of 88%.

Novel post-weld-shift measurement of butterfly-type laser module employing high resolution capacitance displacement measurement technique

A novel capacitance displacement measurement system with 25.4nm resolution and 0.1µm accuracy is employed to on-line measure the PWS of butterfly-type module. The coupling efficiency can be regained up to 90% by this real-time technique.