With ever-increasing demands for high-speed data transmission and device capacity to handle various telecommunication data links, the high reliability of these transmission devices is expected for uninterrupted service. A typical optical communication system consists of transmitters in which laser diodes convert electrical signals into light signals, optical fibers with a few pumps transmitting and maintaining these light signals over long distances, and receivers in which photodiodes convert the light signals back into an electronic form. The efficiency of optoelectronic devices in a communication system, which include transmitters and receivers, plays the most important role in determining the quality and the bandwidth of a communication system. For transmitters, the efficiency is defined as the ratio of the light entering the optical fiber to the light generated by the laser diode. Therefore, the optical fiber should be aligned as precisely as possible with the laser diode to ensure the high efficiency.
For high performance optoelectronic devices, box-type packages including the dual-in-line package (DIP) and butterfly package with fiber-solder-ferrule (FSF) are widely used. An optical fiber with a metallized end is soldered inside a ferrule tube to form the FSF. The FSF is joined on a u-channel mount in front of laser diode by laser welding. No matter where the fiber locates in the ferrule tube, the place for maximum coupling power can be dynamically measured and then the FSF is fixed. But, researches have shown that the redistribution of residual stress and the stress relaxation of creep phenomenon within the solder will push the fiber shift to the geometrical center of the ferrule and the shift reduces the coupling efficiency of laser module after temperature cycle testing. The efficiency is worse when the initial fiber eccentric offset increased. An optimum approach for reduction of the fiber alignment shift in laser module is to solder the fiber near to the center of the ferrule.
A method for automating the FSF packaging process has been developed to fix the fiber within less than 20um of the center of the ferrule. This method makes use of CCD cameras as position sensors to locate the fiber, and compensates all the major sources of inaccuracy resulting from a typical CCD-based packaging system. The accuracy of the fiber position is highly improved from 80um by traditional packaging process to 20um shown in the experiments. Further work is underway to better the accuracy by compensating the minor sources of inaccuracy.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0710102-121544 |
| Date | 10 July 2002 |
| Creators | Chang, Uing-Ching |
| Contributors | Chi-Cheng Cheng, Wood-Hi Cheng, Chen-Wen Yen, Yih-Tun Tseng |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0710102-121544 |
| Rights | unrestricted, Copyright information available at source archive |
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