An optical network is provided. The optical network includes a station to convert a downstream radio frequency (RF) signal to a downstream optical signal and convert an upstream optical signal to an upstream RF signal; and a remote access unit (RAU) to convert the downstream optical signal to a downstream RF signal and to convert the upstream RF signal to the upstream optical signal, wherein the RAU determines a non-transmission band portion on which data is not carried from the downstream RF signal and inputs upstream data in the non-transmission band.