Hybrid optoelectronic backplane bus for multiprocessor-based computing systems

The architecture of a hybrid electrical and optical backplane with multiple bus lines for high performance bus is proposed and bus systems with 2-bus lines at a wavelength of 850 nm are experimentally demonstrated, with a size of collimation lens (here we used graded index (GRIN) lenses) and level of collimation-limited separation of 1.5 mm between the two bus lines. For the new bus system containing multiple bus lines and 9 processor/memory boards, VCSELs (vertical cavity surface emitting lasers) and photodetector arrays, such parameters as power budget, misalignment and packaging related issues are discussed. With the introduction of GRIN lenses into the backplane system, it is found that not only can the signal beam from the VCSELs get collimated, but the angular tolerance of the system is greatly enhanced. The optical backplane bus system developed here is transparent to higher level bus protocols, thus can support standard backplane buses such as Futurebus ⁺, Multi-bus II, and VMEbus