ABSTRACT
Hybrid VLSI-opto-electronics, also called smart pixel technology, has evolved over the last ten years from a worldwide academic research activity to an enabling technology for industrial optical information processing systems. This evolution has been made possible by a variety of factors: (i) the recent integration of micron-size opto-electronic transceivers with VLSI circuits [1,2] (see also chapter D4.4 on the integration of VCSEL with electronics), (ii) the progress carried out in low-cost optical assembly and packaging [3] and (iii) the theoretical studies carried out on the strengths and weaknesses of optics and electronics at the fundamental, material, device and system levels [4-6]. In hybrid VLSI-opto-electronics, the strengths of free-space and guided-wave optical interconnections [7] (huge i/o photonic density, immunity to electromagnetic interference, large fanout capability, automatic impedance matching, etc) are combined with the processing power of electronics to enable the construction of large scale demonstrators which exhibit today the same aggregate bandwidth as that foreseen by the Semiconductor Industry Association (SIA) Roadmap for the year 2007 [8]. Massive parallelism, low input/output driving energy over large distances and synchronous processing of hundreds of optical information input channels allow these demonstrators to provide potentially on/off communication rates in the tera (1012) pin-Hz region. For example, the bitonic sorter, built at Heriot-Watt University, shows a theoretical maximum aggregate throughput rate of the order of 5 × 1011 pin-Hz [9]; an opto-electronic crossbar, built at the same university, will allow a terabit s−1 communication throughput bandwidth between an eight-by-eight VCSEL array and a photodetector array [10].
