3 X 3 Optoelectronic Cross-Bar Switch Using Vertical Cavity Surface Emitting Laser Arrays

Abstract

In an electronic space division switch matrix, the system performance at high frequencies is subject to degradation because of crosstalk due to electromagnetic coupling in adjacent signal paths. A substantial improvement in performance can be obtained if the incoming signals were optical and the outgoing electrical with optical detectors acting as the cross points[1,2]. As the incoming paths are optical, a great degree of immunity to crosstalk can be gained, and the crosstalk that may arise in the outgoing electrical lines could be reduced by proper shielding as the adjacent conductor lines are no longer electrically connected. Such switching matrices may also be applied in high speed analog and digital signal processing applications [3,4]. The signal distribution in optoelectronic switches has been done in the past using 1:N multimode fibre splitters and butt-coupling the fibres to the MSM detectors by prealigning the fibres in etched silicon V-groove arrays. Two drawbacks of the fibre distribution method are that it is very fragile and handling large number of fibres is difficult and time-consuming. Alternative approaches are the use of integrated waveguide devices for power division or free space interconnect. A 3X3 free space switch prototype using three discrete lasers has been previously reported [5]. In this paper a modified version using vertical cavity surface emitting lasers (VCSEL’s) driven by electrical inputs is described.