Aiming at the problem of high latency and low throughput in electric Data Center Network（DCN）

two kinds of passive optical DCN architecture are proposed

one for small DCN and the other for large DCN. Using passive optical devices such as Arrayed Waveguide Grating Router（AWGR）

coupler and demultiplexer

wavelength assignment and packet transmission algorithms are proposed for each scale architecture. The results show that the proposed method has lower latency and higher throughput compared with electric DCN

such as Fat-tree and Flat Butterfly（FBFLY） networks. It is also shown that the performances of proposed optical DCN architectures are similar to those of other optical interconnection architectures（such as Datacenter Optical Switch（DOS） and Petabit）. The packet delay is less than 18 μs with lower cost.