Optical switch changeover controlling method, optical node device and optical switch system

An optical node device comprising:

• a spatial optical switch which is provided with a plurality of optical switch elements arranged between a plurality of input terminals and a plurality of output terminals thereof, each of the plurality of optical switch elements being controllable to change over a connection between two input ports and two output ports into one of a parallel state and an interlaced state and having such a characteristic that a power of optical signal to be output from each of the output ports is continuously changed over from a power of optical signal to be input to one of the two input ports, to a power of optical signal to be input to the other of the two input ports;
• and
• controlling means for controlling the connection state of each of said plurality of optical switch elements of said spatial optical switch to thereby change over setting of optical paths interconnecting between the plurality of input terminals and the plurality of output terminals,
• wherein said controlling means comprises,
• when a first optical path directed from a first input terminal to a first output terminal of said spatial optical switch is changed over to a second optical path directed from a second input terminal to the first output terminal,
• an optical path re-setting part initiating re-setting of said respective optical switch elements for forming said second optical path, while keeping the setting of said respective optical switch elements for forming said first optical path, to prepare a state where, for one optical switch element participating in forming both of said first optical path and said second optical path, one of the two input ports is input with an optical signal from said first input terminal and the other of the two input terminals is input with an optical signal from said second input terminal;
• and
• an optical path reconnection part changing over the connection state of the one optical switch element participating in forming both of said first optical path and said second optical path, set in said optical path re-setting part, to the other connection state to thereby release said first optical path and establish the connection of said second optical path.

An optical switch system comprising:

• an optical switch of crossbar type capable of conducting switching control so as to change over a connection between two input ports and two output ports into one of a parallel state and an interlaced state;
• and
• an optical amplifier provided at one of an input side and an output side of said optical switch;
• wherein said optical switch changes over a ray in an uninterrupted manner, when switching.