<title>Novel surface-mount-type fiber optic transmitter and receiver</title>

Abstract

This paper presents novel surface mount type fiber optic transmitters and receivers suitable for mass-production and high-density installation to the PCBs (printed circuit board) ofthe communication equipment. The transmitters and receivers are applicable for SONET/SDH equipment and fulfill the specifications ofITU-T G.9571 and G. 9582 recommendations.Conventional fiber optic transmitters and receivers have a pigtail cord fasten to their housing. Such a pigtail cord is a constraint factor for reflow soldering and machine mounting ofthe transmitters and receivers to the PCBs in the communication equipment manufacturing process. Therefore, simplified optical connectors, the pigtail fiber cords can be easily attached to (and detached from) them, has been developed.A conventional feedback APC (automatic power control) circuit needs classical variable resistors to adjust LD's (laser diode) bias current (Ib) and pulse current (Ip). This method requires manual adjustment and sites for the variable resistors. The developed fiber optic transmitters are equipped with a digital feed-forward APC circuit to compensate Ide and lac versus the ambient temperature change. In this method a ROM built into LSI stores data for Idc and lac. APC operation is carried out by loading the data from the ROM and giving the data to digital-analog converters.The fiber optic receivers have clock regeneration function utilizing the PLL technology instead of conventional band-pass filter. This scheme aligns the phase delay between received data and extracted clock at the optimum position, thus no manual circuit adjustment is needed