<title>Characterization of a bidirectional optical backplane and performance enhancement with multi bus lines</title>

Abstract

The concept of a bi-directional optical backplane with multi-bus lines for a high performance system containing multi-chip module boards, operating at 850 nm, is introduced. The backplane reported here employs VCSEL arrays and photodetector arrays as transceivers. Optical beams from a transmitter are fanned out by deflectors which are arrays of multiplexed polymer-based waveguide holograms, and then undergo total internal reflection inside a waveguiding plate, and finally reach the target receiver arrays on the edge of boards. We have designed a bi-directional optical backplane for the data communications application in a nine- board system. Packaging related issues such as misalignment, crosstalk and signal to noise ratio have been studied for the reliable system based on the Gaussian beam approximation. By integrating 140 micrometers -pitch or 250 micrometers - pitch VCSEL arrays, microlens arrays, and photodetector arrays into our design of backplane, we have demonstrated optical backplane with multi-bus lines and experimentally realized this architecture with 1D and 2D bus lines which greatly increase the bus bandwidth of the backplane. Frequency responses of our devices shows a bandwidth of 2.5 THz, which is higher bandwidth. Eye diagrams up to 1.5 GHz have been demonstrated with clear eyes.