Optical transmission apparatus, optical transmission system, and optical transmission method

An optical transmission system comprising:

• a first optical transmission apparatus that performs optical transmission;
• and
• a second optical transmission apparatus having a wavelength variable filter whose transmission light wavelength is variable, the second optical transmission apparatus receiving light that is sent from the first optical transmission apparatus and passes through the wavelength variable filter, the second optical transmission apparatus sending to the first optical transmission apparatus, a utilization permission request of a second wavelength corresponding to a first wavelength of the received light, the second optical transmission apparatus sending the utilization permission request as light of the second wavelength and in a form of a tone signal of a predetermined frequency, wherein
• the first optical transmission apparatus sends a utilization permission notification of the second wavelength to a sender of the utilization permission request,
• the second optical transmission apparatus, when receiving the utilization permission notification from the first optical transmission apparatus, sets a wavelength of a main signal to the second wavelength, the main signal being sent to the first optical transmission apparatus.

An optical transmission apparatus comprising:

• a wavelength variable filter whose transmission light wavelength is variable;
• a receiver that receives light, the light being sent from another optical transmission apparatus and passing through the wavelength variable filter;
• a detector that monitors the light received by the receiver while changing a transmission wavelength of the wavelength variable filter from a random wavelength and detects a first wavelength of the light not used by the another optical transmission apparatus to send a first main signal;
• a transmitter that when the first wavelength is detected by the detector, sends a utilization permission request of a second wavelength corresponding to the first wavelength, the transmitter sending the utilization permission request to the another optical transmission apparatus, as light of the second wavelength;
• and
• a controller that when receiving from the another optical transmission apparatus, a utilization permission notification of the second wavelength to a sender of the utilization permission request, sets a wavelength of a second main signal to the second wavelength, the second main signal being sent from the transmitter to the another optical transmission apparatus.