A method and system is disclosed to optically transport data at a data rate of about 5 Gbps without chromatic dispersion compensation. After receiving a first data stream at a data rate of about 2.5 Gbps and a second data stream at a data rate of about 2.5 Gbps, the first and second data streams are combined into a third data stream at a data rate of about 5 Gbps by interleaving the first data stream and the second data stream, wherein the third data stream is modulated for optically transporting the same from a transmission end.