Kaleidoscopic Optical Backplane For Parallel Processing

A laboratory model of a hybrid optical interconnect for board to board communication in a multiple broadcast topology has been built. The hybrid structure contains both free space and guided elements. The device is able to connect 9 processing elements each with a 64 bits output word. So 576 parallel output channels are fanned out to 5184 parallel channels. More processors can be interconnected by stacking these units or by making an adaption of the dimensions and lay-out. The fan-out is provided by multiple imaging of the fiber tips in the input plane by an objective lens and a facet mirror. The crosstalk between two neighbouring 250 μm diameter fiber channels with a pitch of 375μm is as good as -28 dB. The performance of this first non-optimized model showed some image distortion and a mismatch in numerical aperture of the fibers and the imaging optics.