Wavelength cross connect device, branch ratio variable method, and program

A splitting ratio change method for a wavelength cross-connect device for performing a relay by splitting optical signals transmitted from input sides of a plurality of degrees each provided by optical fibers, via respective optical couplers and outputting the split optical signals to output sides of the plurality of degrees via respective WSSs,

• the wavelength cross-connect device using a variable splitting-ratio coupler whose splitting ratio that is a ratio of optical signal power losses in splitting an optical signal is variable is used, as each of the optical couplers,
• the wavelength cross-connect device including a control unit that performs control to change the splitting ratios of the variable splitting-ratio couplers in such a manner as to eliminate an imbalance between optical signal-to-noise ratio margins of the output sides of the degrees in which a plurality of optical paths transmitting the respective optical signals subsequent to the splitting extend,
• the method comprising causing the control unit to perform:
• a step of calculating the respective margins for the plurality of optical paths transmitting the optical signals subsequent to the splitting via the variable splitting-ratio couplers, for the output sides of the respective degrees;
• and
• a step of performing control to, based on respective smallest margins of the degrees, the smallest margins being obtained from all the margins calculated for the output sides of the respective degrees, change the splitting ratios of the variable splitting-ratio couplers in such a manner as to eliminate an imbalance between the margins of the degrees.

A non-transitory computer readable medium storing a program for making a computer that is a wavelength cross-connect device that performs a relay by splitting optical signals transmitted from a plurality of degrees each provided by optical fibers, via respective optical couplers and outputting the split optical signals to output sides of the plurality of degrees via respective WSSs, uses a variable splitting-ratio coupler whose splitting ratio that is a ratio of optical signal power losses in splitting an optical signal is variable, as each of the optical couplers, and performs control to change the splitting ratios of the variable splitting-ratio couplers in such a manner as to eliminate an imbalance between optical signal-to-noise ratio margins of the output sides of the degrees in which a plurality of optical paths transmitting the respective optical signals subsequent to the splitting extend, function as:

• means for calculating the respective margins for the plurality of optical paths transmitting the optical signals subsequent to the splitting via the variable splitting-ratio couplers, for the output sides of the respective degrees;
• and
• means for performing control to, based on respective smallest margins of the degrees, the smallest margins being obtained from all the margins calculated for the output sides of the respective degrees, change the splitting ratios of the variable splitting-ratio couplers in such a manner as to eliminate an imbalance between the margins of the degrees.