In this paper, we introduce the power-efficient design space for multicast wavelength-routed networks. The power-efficient design space is based on the impact of power on the overall design of wavelength-routed networks. Two cross-connect architectures on this design concept are investigated. One is an existing architecture called splitter-and-delivery (SaD). The other is a new architecture called multicast-only splitter-and-delivery (MOSaD). The MOSaD architecture uses power splitters for multicast connections only, allowing unicast connections to pass without enduring unnecessary power losses. Our cross-connect design provides a strictly nonblocking service for unicast connections while eliminating unnecessary power loss of the SaD cross-connect. Experimental results demonstrate that the MOSaD architecture provides substantial savings in cost and reduction in signal power loss with minimal effects on the blocking performance of the network.