Optical transmission system

An optical reception device that receives an optical signal, comprising:

• 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, and performs 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 error correction amount.

An optical transmission device that transmits an optical signal, comprising:

• 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 of an optical reception device based on a combining filter operation temperature when a wavelength transmission band is shifted in a short-wavelength direction or a long-wavelength direction on the side of the optical reception device, the optical wavelength combining unit thereby performing a combining operation on optical signals and outputting a wavelength-multiplexed optical signal;
• and
• a combining filter temperature control unit that sets the combining filter operation temperature based on the error correction amount sent from the optical reception device.

An optical transmission system that performs WDM optical transmission, comprising:

• an optical transmission device that includes:
• an optical wavelength combining unit that performs a combining operation on optical signals, and outputs a wavelength-multiplexed optical signal;
• an optical variable attenuator;
• a correction filter that corrects distortions in accordance with distortion information, the distortions having been caused at the optical wavelength combining unit and an optical wavelength branching unit that performs a branching operation on a wavelength-multiplexed optical signal;
• and an optical performance information receiving unit that receives optical performance information, and outputs an attenuation adjust instruction and the distortion information to the optical variable attenuator;
• and
• an optical reception device that includes:
• the optical wavelength branching unit;
• and an optical performance monitoring unit that measures the bit error rate and the optical level of an optical signal at each wavelength, and outputs the optical performance information.

An optical transmission device that transmits an optical signal, comprising:

• an optical wavelength combining unit that performs a combining operation on optical signals, and outputs a wavelength-multiplexed optical signal;
• an optical variable attenuator;
• a correction filter that corrects distortions in accordance with distortion information, the distortions having been caused at the optical wavelength combining unit and an optical wavelength branching unit on an optical reception device side;
• and
• an optical performance information receiving unit that receives optical performance information from an optical reception device, and outputs an attenuation adjust instruction and the distortion information to the optical variable attenuator.

An optical network system that performs WDM optical transmission, comprising:

• a node that includes:
• an optical transmission unit including 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 unit including 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,
• the node performing either an OADM control operation to carry out “Add”/“Drop” on an optical signal or an optical cross-connect control operation;
• and
• an optical transmission medium that connects a plurality of nodes, each of which is the same type as said node.

An optical transmission method for performing WDM optical transmission control, comprising the steps of:

• gathering an error correction amount by decoding an error correction code for an optical signal at each wavelength on a transmission side;
• setting a branching filter operation temperature based on the error correction amount;
• performing a branching operation on a wavelength-multiplexed optical signal by shifting a wavelength transmission band in a short-wavelength direction or a long-wavelength direction based on the branching filter operation temperature;
• setting a combining filter operation temperature based on the error correction amount;
• performing a combining operation on optical signals to output a wavelength-multiplexed optical signal, by shifting a wavelength transmission band in the opposite direction from the shifting direction on a reception side based on the combining filter operation temperature;
• storing the smallest value of the error correction amount;
• and
• flattening the transmission characteristics of an optical signal by shift-setting an operation temperature at an optimum value based on the smallest value.