On the basis of profound understanding of data center (DC) traffic demands and optical switching technologies, we present a hybrid optical network design for future data center network (DCN). Such design integrates optical circuit switching (OCS) and optical packet switching (OPS) schemes via hybrid Top-of-the-Rack (ToR) switches which provide flexible function-switchover between different traffic patterns in the DCN. Simulations of network behaviors under such DC traffic loads indicate that the proposed OPS/OCS DCN can effectively improve the network performance. Moreover, via a preliminary analysis of OCS and OPS network configurations, the construction of hybrid DCN is also proved as the most cost- and energy-efficient way for DCN upgrading while offering a promised quality of service. An experimental demonstration shows a complete implementation of data center virtualization in the proposed hybrid data center network.