A Free Space Optical Crossbar Switch Using Wavelength Division Multiplexing and Vertical-Cavity Surface-Emitting Lasers

Building large crossbar switches for low-latency, highbandwidth interprocessor interconnects in multiprocessor systems is a difficult task because of the many practical limitations of digital electronics. This paper presents a first order design for a crossbar switch which utilizes wavelength tunable vertical-cavity surface-emitting laser (VCSEL) technology and free space optics. Free space optics can be utilized to construct a crossbar switch without the wiring complexity normally associated with digital electronic crossbar. Wavelength tunable VCSELs can be utilized to reduce the required number of components per node to as few as one wavelength tunable VCSEL and one fixed frequency receiver, thereby reducing the overall cost. By utilizing space division multiplexing, one can further increase the size of the optical crossbar switch by adding additional wavelength tunable VCSELs at each node, greatly increasing the salability of the overall system. An example system configuration containing 256 channels is presented.