We investigate the post-weld-shift(PWS) induced fiber alignment shift in butterfly laser packaging. For high-speed laser modules in lightwave communication systems, the butterfly laser modules are widely used. When laser welding is applied to assemble a butterfly package, it is usually necessary to have mechanical elements such as substrates, fiber ferrule, and clip of house materials to facilitate fiber handing and retention within the package. However, during the process, rapid solidification of the welded region and associated material shrinkage often cause a post-weld-shift between welded components. The PWS significantly affects the package yield. A novel measurement and compensation technique employing a high-magnification camera with image capturing system (HMCICS) to probe the post-weld-shift (PWS) induced fiber alignment shifts in high-performance butterfly-type laser module packages is studied. The results show that the direction and magnitude of the fiber alignment shifts induced by the PWS in laser-welded butterfly-type laser module packaging can be quantitatively determined and then compensated. The increased coupling efficiency after this PWS compensation was from 3% to 10%. This HMCICS technique has provided an important tool for quantitative measurement and compensation to the effect of the PWS on the fiber alignment shifts in laser module packages. Therefore, the reliable butterfly-type laser modules with a high yield and a high performance used in lightwave transmission systems can be developed.

A notch clip approach to compensate post-weld-shift(PWS) induced by laser welding process in butterfly type laser module packages is investigated. For high-speed laser modules in lightwave communication systems, the butterfly laser modules are widely used. When laser welding is applied to assemble a butterfly package, it is usually necessary to have mechanical elements such as substrates, fiber ferrule, and clip of house materials to facilitate fiber handing and retention within the package. However, during the laser welding process, rapid solidification of the welded region and associated material shrinkage often cause a post-weld-shift between welded components. The PWS significantly affects the package yield. A notch clip approach and measurements employing a high-magnification camera with image capturing system (HMCICS) to probe the PWS induced fiber alignment shifts and welding compensation on notch in high-performance butterfly-type laser module packages are studied. The results show that the direction and magnitude of the fiber alignment shifts induced by the PWS in laser-welded butterfly-type laser module packaging can be quantitatively determined and then compensated. The overall coupling efficiency after this PWS compensation was from 80¢H to 90¢H. This notch approach and HMCICS technique have provided an important tool for quantitative measurement and compensation to the effect of the PWS on the fiber alignment shifts in laser module packages. Therefore, the reliable butterfly-type laser modules with a high yield and a high performance used in lightwave transmission systems can be developed.

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A novel technique by employing a capacitance displacement measurement system to measure the post-weld-shift (PWS) caused by laser welding in the butterfly-type laser diode module packaging process is proposed. Reduction of the PWS is an important issue in developing low-cost and high-performance semiconductor laser module. Prior to the reduction and compensation of the PWS, a measurement system of PWS must be constructed. In comparison to the high-magnification camera with image capturing system (HMCICS) limited in resolution of 0.07£gm due to its pixels, a measurement system with a higher resolution of 0.0254£gm is used. During the measurement procedure, the PWS of the ferrule probed by the sensors is converted into the fiber misalignment shifts. The coupling efficiency can be improved over 70% after compensation. The result indicates that the PWS can be qualitatively measured and quantitatively computed.

In this study, the capacitance displacement system (CDS) is employed to measure the post-weld-shift (PWS) induced by laser welding in butterfly type laser module package. The advantage of CDS is able to simultaneously and immediately measure the direction and the magnitude of PWS. Furthermore, with the aid of notch clip, the PWS can efficiently and quantitatively be compensated by laser hammering technique to regain the coupling power. Reduction of the PWS is an important issue in developing low-cost and high-performance laser modules. The package yield of laser modules can be imp roved due to the real-time measurement and quantitative compensation. In comparison with the high-magnification camera with image capturing system (HMCICS) having 0.7£gm resolution, the capacitance sensor achieves 25.4nm and 0.1£gm in its resolution and accuracy, respectively. Besides, during the package procedure, the real-time displacement detection can be used to adjust the package parameters. As a result, the PWS is reduced that contributes to less coupling power loss. After welding, the result reveals that the PWS was measured as X=0.15£gm and Y=-4.58£gm, while the coupling power is 43.19%.

The post-weld-shift (PWS) introduced in the butterfly laser packaging is investigated in this study. The elastic-plastic-thermal coupled finite element model is employed in the stress and deformation analyses. The temperature dependent material properties are used to calculate the residual stresses and the post-weld shift distributions during the packaging process. The finite element package ¡¥MARC¡¦ is used in this study. And the commercial optical software, i.e. ¡¥Zemax¡¦ is also employed in laser power coupling efficiency simulation. The variations of laser welding sequence, Nd-YAG pulse laser power, and initial ferrule¡¦s alignment position on PWS for butterfly laser packaging are studied and discussed in this work. The results indicated adjust the sequence and pulse laser power properly can improve the PWS in butterfly packing significantly. Besides, the PWS correction technique, i.e. the ¡¥Laser Harmering¡¦, is also illustrated in this study. The simulate results showed that proper arrange the welding processes may improve the coupling efficiency over 75¢M.

For getting the position which can obtain the maximum coupling efficiency, fiber array and laser array need to be adjusted while the module of fiber array is packaging, than fastening it on the base. Nowadays, there are some methods for fastening the fiber array like adhesive, soldering and laser welding. But the material will discover some phenomenons like expansion and contraction during the process of heating and solidification. Those phenomenons will lead the system to deviate on the six degree of freedom (D.O.F). Because of the fiber array system will confront with the situation of deviation, the magnitude of coupling efficiency will drop down. It is because that the technique of laser welding will cause smaller deviation than other methods just mentioned, so the research choose the method of laser welding for packaging. The distance between fiber and laser array is too small to fasten the CCD on the directions of X, Y and Z axes while the research measures the deviation. So the research uses a mirror to reflect the image for obtaining the correct position of the space and Post-Weld-Shift measurement the deviation of system. Afterward, the research designs a structure for reducing the deviation and increasing the coupling efficiency of system.

The effect of residual stress on the post-weld-shift (PWS) of a fiber-solder-ferrule (FSF) under a cyclic thermal load is investigated in this thesis. By using the finite element software MENTAT and MARC, the stress distribution in this model of coupled thermal-elastoplasticity is adopted to solve. The temperature dependent material properties are employed to calculate the residual stresses and the thermal stresses of the solder in the solidification process. The PWS of a fiber and the stress distribution of a solder under different temperature cycles are also investigated in this study. The PWS calculated with and without considering residual stresses are compared with the measured data in this study. Results indicated that the effects of residual stresses introduced in the solder solidification can not be ignored. The temperature dependent material properties, i.e., the melting temperature , Young¡¦s Modulus, coefficient of thermal expansion (CTE) and yield strength at high temperature may affect the residual stress distribution and the PWS of the FSF significantly.

Abstract In this thesis, we have studied the post-weld-shift (PWS) in laser welding technique for laser module packaging. The joining method for packaging of laser module by laser welding technique can offer a number of significant advantages. It provides strong joint strength, therefore, the packaging has good long-term stability. It also provides high-speed and high-volume production, and hence the packaging is potential low cost. However, the laser welding process has caused PWS of laser module, would decay the coupling efficiency of laser module. We investigate the weld-spot by using metallographic method. The PWS in stainless steel (SS304L) plate is studied experimentally and numerically. The metallographic results are in good agreement with the Finite-Element-Method (FEM) results that the PWS in x-y plane can be neglected. Based on the experimentally and numerically results of PWS in SS304L, we investigate the yield improvement of laser module packaging. The laser hammer technique was used to improve the coupling efficiency of laser module. The results show displacement of the z-axis is from 1 to 9 (£gm) that equals to the angle changes of upper parts of laser module from 0.38¡Ñ10-2 to 3.4¡Ñ10-2 (degree). Therefore, the coupling efficiency of laser module can be improved from 4 to 20 (%).

The fiber clips is a device for holding an optical fiber which is enclosed in the ferrule, adjustment it to the optimum aligning position with respect to the laser diode and fixing it on the substrate of the butterfly-type laser module by the laser welding. It is hard for the extant saddle shaped clips to be manufactured and the result causes the unable mass production and the high cost. Otherwise, the packaging process has caused PWS of laser module, would decay the coupling efficiency of laser module. Aim at the shortcomings, the purpose of this study proceeds to the creative design of the fiber clips with the systematic engineering design and make a set of the manufacturing method by the pressing die to cause automatic mass production in the future. First, identify the basic characteristics based on an analysis of the patents and then get the conditions and trend. Second, find the function needs and elaborate the specification of design. Third, the use of morphological analysis method and design process is formulated to synthesize and evaluate the improving structure. Finally, taking the design cases will develop the embodiment design and prove the propose approach for the design process. Otherwise, it develops an improvement technique and adjustment method for PWS and wishes can reduce or improve the effects of it.