Packaging aspects of the LitebusTM parallel optoelectronic module

The Litebus module is an optoelectronic transceiver and the key component in a parallel fiber optic data link. The module is designed to extend computer-to-computer communications to data rates and link distances beyond those achievable in copper at comparable cost. A transceiver configuration was selected to keep the module´s size compact (45 mm×32 mm× 9.8 mm) and to facilitate the integration of an IEC Class 1 laser safety strategy. The Litebus module consists of various packaging components and both CMOS and optoelectronic dies. It is designed to accept a single connector, having one receive and one transmit section, that is mounted on the end of a dual 12 channel fiber optic ribbon cable. Channel-to-channel spacing is 250 μm throughout and standard multimode fiber is used. The transmitter consists of a VCSEL (Vertical Cavity Surface Emitting Laser) source having a wavelength of 850 nm. The receiver consists of a transimpedance amplifier with integrated Metal-Semiconductor-Metal (MSM) detector. The module´s transmit and receive sections were designed to operate at data rates greater than 1.25 Gb/s (gigabits per second) per channel, yielding a maximum aggregate data rate in excess of 15 Gb/s. In one mode of operation, byte-wide data is simultaneously transmitted from and received by the module at 1.25 GB/s (gigabytes per second), with the four remaining channels on each side being assigned to user-defined overhead functions. The maximum cable length is 400 m in asynchronous mode and 200 m in synchronous mode