<title>Free-space optical wavelength-division multiple-access networks for parallel computation</title>

Abstract

A novel optical free-space mesh-connected bus (MCB) interconnect network architecture is proposed. An MCB is known to have the capability of interconnecting, using a three-stage switching, N nodes with a power distribution loss proportional to (root)N, and is therefore advantageous for networking a large number, say over 1000, of communicating ports. Based on conventional space-invariant optical components in a compact and efficient geometry, the proposed optical MCB system concept can be used to build either free-space optical interconnect links for parallel processing applications or central switching systems for local or global lightwave communication networks. The proposed architecture lends itself for networking under both the wavelength-division multiple-access (WDMA) and other multiple- access environments. In this paper, based on the WDMA environment, various optical system implementation and performance issues are discussed and parameters are analyzed. It was found that using a reasonably compact three-dimensional free-space volume, more than 100,000 dispersion-limited communication nodes at a uniform channel spacing of 0.75 nm can be linked with a moderate PDL of 28 dB. Some preliminary optical WDMA MCB experiments based on a 27 X 27 panchromatic optical source array were performed to confirm the operational principle of the proposed concept.