Optical branching/coupling device and optical branching/coupling method

An optical branching/coupling method comprising:

• receiving a first optical signal from a first line;
• outputting, to the first line, a third optical signal acquired by multiplexing the first optical signal with a second optical signal to be inserted into the first line;
• receiving, from a second line different from the first line, a sixth optical signal acquired by wavelength-multiplexing a fourth optical signal with a fifth optical signal to be dropped from the second line;
• demultiplexing the fourth optical signal and the fifth optical signal;
• and
• outputting, to the second line, a seventh optical signal acquired by multiplexing the fourth optical signal with the first optical signal.

A tangible and non-transitory recording medium for a program for causing a computer of an optical branching/coupling device to execute:

• a procedure of outputting, to a first line, a third optical signal acquired by multiplexing a first optical signal received from the first line with a second optical signal to be inserted into the first line;
• a procedure of receiving, from a second line different from the first line, a sixth optical signal acquired by wavelength-multiplexing a fourth optical signal with a fifth optical signal to be dropped from the second line;
• a procedure of demultiplexing the fourth optical signal and the fifth optical signal;
• and
• a procedure of outputting, to the second line, a seventh optical signal acquired by multiplexing the fourth optical signal with the first optical signal.