A Scalable AWGR-Based Optical Switch

The energy-per-bit efficiency has quickly become the ultimate limiting factor in the design of a switching fabric for routers and data center networks. People are now turning to optics for solutions. If switch fabrics can be implemented with optics, many E/O and O/E conversions will be removed and tremendous power saving can be achieved. Arrayed waveguide grating routers (AWGRs) provide the most promising solution in this regard. But AWGRs have one fundamental limitation: poor scalability. While the realistic port count of an AWGR is likely to be less than 50, a switch for a data center network may need to interconnect one thousand racks, or more. This paper presents a novel AWGR-based switch architecture which, without using wavelength converters, can expand the switch size from N to N-2, where N is the number of wavelengths in the AWGR. Each port can transmit up to N wavelengths simultaneously. This makes the total capacity of the switch close to (N-3 x bandwidth of a wavelength channel). A detailed analysis of the performance of the switch is provided in this paper.