A compact MU-interface, 2,5-Gb/s optical transmitter module with LD-driverIC embedded in L-shaped wiring substrate

A 6.2-cc MU interface optical transmitter module has been developed in a co mpact packaging configuration that allows modules to be mounted side by sid e on a system board. The module employs an MU receptacle for optical output and miniature coaxial receptacles for electrical input. An L-shaped high-s peed wiring substrate in a package cavity allows thermal isolation of a las er-diode driver IC (LD-DR) from the 1.55-mu m distributed feedback laser di ode (DFB-LD) mounted on a thermoelectric (TE) cooler. A confocal two-aspher ic-lens circuit is used for high-performance coupling of the DFB-LD to a di spersion-shifted fiber (DSP). A module using the proposed configuration has been evaluated at temperatures from 10-65 degrees C. Experiments with the module showed good electrical performance at a bit rate of 2.5 Gb/s, low po wer dissipation (less than 1.8 W; only 0.33 W for the LD-DR), and high opti cal coupling efficiency (over 50%).