Most datacenter network designs overwhelmingly use expensive and power-consuming electronic switches or expensive active optical switches with long reconfiguration time. In this thesis, we explore architectural solutions to leverage the design elements of Passive Optical Cross-Connection Networks with Multiple Planes (POXN/MPs) and Passive Optical Cross-Connection Networks with Multiple Planes and Bundled Ports (POXN/MP-BPs), both of which consist primarily of passive optical fabrics and optical transceivers that replace groups of switches in either hierarchical or recursively defined networks. Through simple physical interconnections, our proposed architectures allow datacenters to incrementally scale up in network capacity and scale out in total number of racks with low cost and power consumption. To lower overhead and adapt to the types of real datacenter scenarios that are possible with POXN/MP-BPs, we propose the new Multiple Channels with Bundled Ports Distributed Access Protocol (MCBDAP), which benefits applications involving higher proportions of inter-rack traffic than intra-rack traffic.