Browsing by Author "Cheng, WH"

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A simple passive-alignment packaging technique for laser diode modules
(1998-10-01)
Wang, SC
;
Chi, S
;
Cheng, WH
;
光電工程學系
;
Department of Photonics
A simple passive-alignment packaging technique has been developed for the fabrication of a laser diode connection to a singlemode fiber pigtail. The fabrication begins with a multimode fiber soldered in a U-groove with 5 mu m tolerance. Then the laser chip with a junction-up die-bond is passively aligned to a multimode fiber and converted into a singlemode fiber. The tolerance as measured for the multimode fiber at 10% loss of maximum coupling from the laser diode is 11 mu m. Because the tolerance of the multimode fiber from the laser chip is larger (11 mu m) than that of the fiber in the U-groove (5 mu m), this passive alignment is easily obtained. In contrast to other passive-alignment techniques, the advantages of this technique are that it is less sensitive to transverse misalignment and requires no complicated alignment marks. From laser to multimode fiber a coupling efficiency of greater than 80% and a bandwidth of greater than 1 GHz have been achieved. In this package, the overall coupling efficiency from laser to singlemode fiber is 16%, The resulting laser module with compact size and fewer components should make it highly suitable for use in low-cost telecommunication applications, (C) 1998 Elsevier Science S.A. All rights reserved.
A simple passive-alignment packaging technique for laser diode modules
(1998-10-01)
Wang, SC
;
Chi, S
;
Cheng, WH
;
光電工程研究所
;
Institute of EO Enginerring
A simple passive-alignment packaging technique has been developed for the fabrication of a laser diode connection to a singlemode fiber pigtail. The fabrication begins with a multimode fiber soldered in a U-groove with 5 mu m tolerance. Then the laser chip with a junction-up die-bond is passively aligned to a multimode fiber and converted into a singlemode fiber. The tolerance as measured for the multimode fiber at 10% loss of maximum coupling from the laser diode is 11 mu m. Because the tolerance of the multimode fiber from the laser chip is larger (11 mu m) than that of the fiber in the U-groove (5 mu m), this passive alignment is easily obtained. In contrast to other passive-alignment techniques, the advantages of this technique are that it is less sensitive to transverse misalignment and requires no complicated alignment marks. From laser to multimode fiber a coupling efficiency of greater than 80% and a bandwidth of greater than 1 GHz have been achieved. In this package, the overall coupling efficiency from laser to singlemode fiber is 16%, The resulting laser module with compact size and fewer components should make it highly suitable for use in low-cost telecommunication applications, (C) 1998 Elsevier Science S.A. All rights reserved.
Direct evidence of Au segregation in laser welded Au-coated Invar material
(1997-08-01)
Wang, SC
;
Chi, S
;
Hsieh, KC
;
Yang, YD
;
Cheng, WH
Evidence of the Au segregation within the crack region in laser welded Au-coated Invar material for semiconductor laser packaging is investigated. Results obtained from the metallography, scanning electron microscope (SEM) mapping, energy dispersive spectrometer (EDS) Line profile,and Auger electron spectroscopy find that the cracks in the welded joints occur around the Au rich boundaries. The SEM Au mapping and EDS line profiles show that Au accumulates at the crack region. This direct observation indicates that one of the primary causes of cracks in laser welded Au-coated materials is due to the segregation of Au in the final stage of solidification. Detailed knowledge of the defect formation mechanisms in laser welded Au-coated materials is important for the practical design and fabrication of reliable optoelectronic packaging.
Effect of Au thickness on laser beam penetration in semiconductor laser packages
(1997-11-01)
Cheng, WH
;
Wang, SC
;
Yang, YD
;
Chi, S
;
Sheen, MT
Comprehensive measurements of the dependence of the weld width, penetration depth, and joint strength on the Au coating thickness in laser welding techniques for semiconductor laser packages are presented. The results obtained from the Invar-Invar joints show that the welded joints with thick Au coating exhibit narrower weld width, shallower penetration, and hence less joint strength than those the package joints with thin Au coating, A finite-element method (FEM) has been carried out on the effect of Au thickness on laser beam penetration in Invar-Invar joints, This method has been employed successfully Po predict the laser beam penetration in laser welded An-coated materials that the weld width and the penetration depth are reduced as the Au coating thickness increases, The likely cause for the reduction is the increased thermal conduction of thicker Au in the welded region, in addition to Au coating, the effect of Ni coating on laser beam penetration is also presented, Detailed knowledge of the effect of;in coating thickness on laser beam penetration is important for the practical design and fabrication of reliable optoelectronic packaging having laser welded Au-coated materials.
Effect of thin film coating of Au on joint strength in Invar-Invar packages
(1996-11-01)
Wang, SC
;
Wang, CM
;
Wang, C
;
Chang, HL
;
Tu, YK
The effect of a thin film coating of Au on the joint strength, weld width, and penetration depth in laser welding techniques for Invar-Invar packages is investigated experimentally. It is found that the joint strength, weld width, and penetration depth are strongly dependent on the coating of Au thickness on the Invar material. The welded joints with thick Au coating show narrower weld width, shallower penetration, and hence less joint strength than those of the packages with thin Au coating. The increase in both the thermal conductivity and the vapor volume in the welded joints as the coating of Au thickness increases are the possible mechanisms for the reduction. Detailed knowledge of the effect of thin film coatings of Au on the welded materials, which gives both the highest joint strength and good adhesion, is essential for practical design and fabrication of reliable optoelectronic packaging.