Optical network has been deployed widely as one of the most important physical infrastructure because of the advantages of high capacity, long transmission distance, and low energy consumption. Then how to exploit the potentiality of optical networks gets more and more attention, especially in the current data center networks. Optical as a service (OaaS) is proposed and designed to provide the optical network resources directly for the data centers with considering both data center and network resources, which can be implemented with software defined networking (SDN). Under SDN enabled OaaS architecture, a new concept of network provisioning is proposed different from legacy connection (lightpath) provisioning, because the client’s requests may include not only one end-to-end connection, but also several end-to-end connections, even a network. Also network with edge resources can be provided for the clients. A virtualization engine is designed in SDN enabled OaaS to efficiently complete the network provisioning. As a generalized optimization strategy in SDN enabled OaaS, the cross stratum optimization (CSO) strategy is described by considering both data center and network resource in the paper. Finally the SDN enabled OaaS testbed is demonstrated.