Optical switch module and optical relay apparatus and path expansion method that use optical switch module

A path expansion method of a system including a first optical switch module and a second optical switch module,

• wherein both the first optical switch module and the second optical switch module includes
• N first input ports to which an optical signal is input,
• M first output ports from which an optical signal is output,
• an M×N switch configured to include N second input ports and M second output ports, and to set an optical path between the N second input ports and the M second output ports, the M second output ports coupling with the M first output ports, respectively,
• a test signal input port to which a test signal is capable of being externally input,
• an expansion port from which one of the test signal and the optical signal from any one of the N first input ports is output, and
• an optical switch configured to selectively connect at least one of the test signal and the optical signal from any one of the N first input ports to at least one of the expansion port and any one of the N second input ports,
• the path expansion method comprising:
• connecting the expansion port of the first optical switch module to the test signal input port of the second optical switch module;
• switching a setting of the optical switch of the first optical switch module so as to connect the test signal to the expansion port;
• monitoring, at the second optical switch module, the test signal input from the test signal input port of the first optical switch module,
• checking a connection between the first optical switch module and the second optical switch module, based on a result of the monitoring;
• and
• switching the setting of the optical switch of the first optical switch module so as to connect the optical signal from any one of the N first input ports to the expansion port,
• wherein both N and M are natural numbers.