Electromagnetic shielding of plastic material in laser diode modules

Electromagnetic shielding of plastic materials in laser modules was studied experimentally and theoretically. The conductive carbon fiber fillers into plastics to produce electrically conductive composites were proposed for the evaluation of electromagnetic interference (EMI) shielding effectiveness (SE). The different volume fractions of conductive carbon fiber fillers ranging from 5, 10, 20, and 30% were used. The SE of conductive plastics was measured to be 45 dB at the low frequency of 30 MHz and 60 dB at the high frequency of 1 GHz. The measured results are in good agreement with the calculated results. The laser modules have a transmission speed up to 622 Mb/s and more than 1 mW fiber output power. With these excellent SE and good optical characteristics, plastic MiniDIL laser modules are suitable for use in low-cost OC-12 lightwave transmission systems.