Unguided optical communication bus for next-generation computers: Design concept

In order to further scale down the size of computers and increase their speed, optical technology is expected to substitute electrical technology for inter-chip motherboard communication. The increasing inter-chip requirements makes it extremely difficult to overcome the delay, power, and bandwidth limitations of the existing electrical wires technology In this research, unguided optical communication bus (UOCB) design for inter-chip communication is analyzed. A UOCB includes transceiver arrays for each chip that transmit information without a waveguide, such that an array of beams propagates through a solid plate. The solid plate is the computer motherboard and is used to hold the chip physically and, in addition, as a propagation medium for the communication beams. The bus space is reused, or multiplexed, such that more than one beam propagates though it simultaneously. The communication through the bus takes advantage of the scattering effect, reflection and diffusion from the walls. We examined the data transmission requirement for uncorrelated optical communication paths between the multiple-input multiple-output (MIMO) optical receiver and transmission arrays over highly diffused propagation bus. Each optical communication path between potential receiver and transmitter locations was described in terms of the optical channel gain, representing the individual optical path. An example of a MIMO gain matrix H between multiple spatial locations was evaluated.