Contents I. Introduction
Recently, it has been reported that traffic demand on the Internet doubles for every two years. To handle the increasing traffic, new standards for 100-Gbit/s Ethernet are being prepared (1). For the 10-km transmission standard (100GBASE-LR4), four-channel 25-Gbit/s light sources and photodetectors are used in a LAN-WDM configuration. These optical devices require not only a high-frequency capability but also cost-effective packaging. To meet these requirements, some approaches have been proposed (2, 3). In the approach in Ref. 2, signal pins of the package are soldered to a flexible printed circuit board (FPC) in a straight line to reduce the electrical reflection.
