A optical transmitting system and optical transmitting apparatus thereof

An optical transmission system comprising an optical transmitting apparatus for transmitting an optical signal to an optical fiber and an optical receiving apparatus for receiving the optical signal transmitted via the optical fiber, wherein the optical transmitting apparatus comprises a distributor for distributing a main signal which has an irregular waveform pattern and which is in a radio frequency band into two, a frequency converter for down-converting distributed one main signal into a low-band signal in a band lower than the radio frequency band, a mixer for synthesizing the distributed other main signal with the low-band signal, and an electric/optical converter for converting a main signal synthesized with the low-band signal into the optical signal by the mixer and outputting it to the optical fiber, and wherein the optical receiving apparatus comprises an optical/electric converter for converting the optical signal coming via the optical fiber into an electric signal, and a high-pass filter for eliminating the low-band signal from the converted electric signal.