A compact MU-interface, 2.5-Gb/s optical transmitter module with LD-driver IC embedded in L-shaped wiring substrate

A 6.2-cc MU interface optical transmitter module has been developed in a compact packaging configuration that allows modules to be mounted side by side on a system board. The module employs an MU receptacle for optical output and miniature coaxial receptacles for electrical input. An L-shaped high-speed wiring substrate in a package cavity allows thermal isolation of a laser-diode driver IC (LD-DR) from the 1.55-μm distributed feedback laser diode (DFB-LD) mounted on a thermoelectric (TE) cooler. A confocal two-aspheric-lens circuit is used for high-performance coupling of the DFB-LD to a dispersion-shifted fiber (DSF). A module using the proposed configuration has been evaluated at temperatures from 10-65°C. Experiments with the module showed good electrical performance at a bit rate of 2.5 Gb/s, low power dissipation (less than 1.8 W; only 0.33 W for the LD-DR), and high optical coupling efficiency (over 50%)