  The many cores design research community have shown high interest in optical
crossbars on chip for more than a decade. Key properties of optical crossbars,
namely a) contention-free data routing b) low-latency communication and c)
potential for high bandwidth through the use of WDM, motivate several
implementations. These implementations demonstrate very different scalability
and power efficiency ability depending on three key design factors: a) the
network topology, b) the considered layout and c) the insertion losses induced
by the fabrication process. The emerging design technique relying on
multi-layer deposited silicon allows reducing optical losses, which may lead to
significant reduction of the power consumption. In this paper, multi-layer
deposited silicon based crossbars are proposed and compared. The results
indicate that the proposed ring-based network exhibits, on average, 22% and
51.4% improvement for worst-case and average losses respectively compared to
the most power-efficient related crossbars.
