Hybrid Micropackaging for Optoelectronic Multi-Chip Modules

Hybrid integration of optoelectronic and electronic components to form multi-chip modules provides a route to the cost-effective fabrication of high-performance devices for avionics, datacomms and fibre-to-the-home applications. The hybrid approach allows the choice of the most appropriate technology for the fabrication of each sub-component; e.g. GaAs or InP based lasers or detectors, Si or GaAs integrated circuits, low-loss silica waveguides. Careful design is required, however, for the mounting of devices to ensure that the optical and electrical performance is not impaired. A hybrid micropackaging scheme may need to address some or all of the following issues: stable and efficient optical interfacing between detector, laser or LED and fibre or waveguide; provision of low-loss waveguides for optical signal routing or processing; provision of laser driver and receiver circuits with impedance-matched interconnect for data input/output, dc interconnect and ground plane for screening. Efficient heat dissipation from active components must also be considered. In many optoelectronic modules the accurate positioning and fixing of the optical fibre in a critical alignment to the optoelectronic chip dominates the assembly and packaging costs. For wider deployment of optoelectronic modules, it is thus desireable to use a packaging scheme that reduces the cost of the fibre interfacing operation, by passive alignment of components. Silicon, now used for electronic multi-chip module carriers, is also a good choice for optoelectronic hybrid modules, offering a good expansion match to InP and GaAs, acceptable thermal conduction, the formation of microetched features such as accurate V-grooves for fibre location(1) and is compatible with the fabrication of silica-on-silicon waveguides.