Patent ID: 7113700

Claim:
An optical transmission system that performs WDM optical transmission, comprising: an optical transmission device that includes: a transmission transponder that performs encoding on an error correction code for an optical signal at each wavelength; an optical wavelength combining unit that shifts a wavelength transmission band in the opposite direction from the shifting direction on a reception side based on a combining filter operation temperature, so as to perform a combining operation on optical signals and output a wavelength-multiplexed optical signal; and a combining filter temperature control unit that sets the combining filter operation temperature based on an error correction amount sent from the reception side; and an optical reception device that includes: an optical wavelength branching unit that shifts a wavelength transmission band in a short-wavelength direction or a long-wavelength direction based on a branching filter operation temperature, so as to perform a branching operation on a wavelength-multiplexed optical signal; a reception transponder that performs decoding on an error correction code for an optical signal at each wavelength; an error correction monitoring unit that gathers an error correction amount from the reception transponder; and a branching filter temperature control unit that sets the branching filter operation temperature based on the gathered error correction amount.