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Low-cost MiniDIP laser modules fabricated by plastic moulded technology filled with highly conductive materials are proposed for the evaluation of electromagnetic interference (EMI) shielding effectiveness (SE). The SE of conductive plastics was measured to be 45 dB at 30 MHz and 62 dB at 1 GHz. The laser modules have a transmission speed up to 622 Mbit/s and > 1 mW fibre output power. With these excellent SEs and good optical characteristics, such plastic MiniDIP laser modules are suitable for use in low-cost OC-12 lightwave transmission systems.
Introduction: The widespread deployment of low-cost optical access networks for fibre subscriber loop applications will necessitate a consid- erable reduction in the cost of key components such as laser modules. Laser module costs are primarily dependent on packaging. Owing to its low-cost nature and ease of manufacture, plastic packaging technology has been considered to be one of the major choices for reducing the costs of fabricating optical modules for use in lightwave transmission systems [1, 2].
Electronic appliances are usually housed in plastic packaging. Plas- tics alone are inherently transparent to electromagnetic radiation and provide no shielding against electromagnetic interference (EMI). There- fore, metal-like properties have been added to plastics to insure adequate electromagnetic (EM) shielding for electronic plastic packaging applica- tions [3]. Despite numerous reports on electronic plastic packaging for EM shielding, only limited information is available about low-cost plas- tic optical modules for EM shielding. In the study presented in this Let- ter cost-effective plastic packaging technology that incorporates laser welding bonding to simplify optical alignment between the laser chip and optical fibre [4] has been investigated to evaluate its EMI shielding effectiveness (SE). This work has led to the development...