Multipath interference analysis device and multipath interference analysis method
A multipath interference analysis device includes a statistical amount calculation unit that calculates statistical amounts of respective measurement values of splice loss measured from a plurality of optical fiber pieces for forming an optical transmission line, and measurement values of cutoff wavelength, a determination unit that determines a truncated normal distribution from a normal distribution of the cutoff wavelength, a random number generation unit that generates random numbers for selecting a predetermined number of pieces of splice connection targets of the optical transmission line, and an MPI value calculation unit that calculates an MPI value using a mode dependent loss of a fundamental mode of the optical transmission line formed of each piece selected according to the random numbers, and a splice interval.
1 . A multipath interference analysis device comprising:
a statistical amount calculation unit, comprising one or more processors, configured to obtain a normal distribution of a cutoff wavelength through calculation of statistical amounts of average values and variance values of respective measurement values of splice loss and the cutoff wavelength measured from a plurality of optical fiber pieces each having a predetermined length for forming an optical transmission line;
a determination unit, comprising the one or more processors, configured to truncate the normal distribution of the cutoff wavelength at predetermined lower and upper limit values of the cutoff wavelength to determine a truncated normal distribution;
a random number generation unit, comprising the one or more processors, configured to generate random numbers for selecting a predetermined number of optical fiber pieces of splice connection targets forming the optical transmission line, on a basis of the determined truncated normal distribution; and
a multipath interference (MPI) value calculation unit, comprising the one or more processors, configured to calculate an MPI value in the optical transmission line formed of the predetermined number of optical fiber pieces selected according to the random numbers using a mode dependent loss in a fundamental mode and a splice interval of the optical transmission line, the MPI value being a value of multipath interference caused by the cutoff wavelength and the splice loss.
2 . The multipath interference analysis device according to claim 1 , wherein the MPI value calculation unit is configured to substitute a fundamental mode loss coefficient: α 01 and the splice interval: ΔL into an equation,
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l: Splice at which optical power transitions from fundamental mode to high-order mode
m: Number of splices crossed by optical power in high-order mode
k: Splice number
Δα (k) =α 11 −α 01 : Mode dependent loss
α 11,(k) =(19.34/ΔL)X (λsig-λc,(k))/10 : Transmission loss in high-order mode
η k =1-10 −εk/10 : Power coupling coefficient
ε k : Splice loss
η 1 η m→1 /(1−η 1 ) (1−η m+1 ): Coupling coefficient of optical power of all splices
λ c,(k) : Cutoff wavelength between splices
λ sig −λ c,(k) : Difference between input optical signal wavelength to optical transmission path and cutoff wavelength, to calculate the MPI value.
3 . The multipath interference analysis device according to claim 2 , wherein the MPI value calculation unit includes an MPI average value calculation unit configured to repeat calculation of the MPI value a predetermined number of times and to calculate an average value of the MPI values calculated by repeating the calculation the predetermined number of times.
4 . The multipath interference analysis device according to claim 1 , wherein the MPI value calculation unit includes an MPI average value calculation unit, configured to repeat calculation of the MPI value a predetermined number of times and to calculate an average value of the MPI values calculated by repeating the calculation the predetermined number of times.
5 . A multipath interference analysis method using a multipath interference analysis device,
obtaining a normal distribution of a cutoff wavelength through calculation of statistical amounts of average values and variance values of respective measurement values of splice loss measured from a plurality of optical fiber pieces each having a predetermined length for forming an optical transmission line and measurement values of the cutoff wavelength measured from the optical fiber pieces;
truncating the normal distribution of the cutoff wavelength at predetermined lower and upper limit values of the cutoff wavelength to determine a truncated normal distribution;
generating random numbers for selecting a predetermined number of optical fiber pieces of splice connection targets forming the optical transmission line, on a basis of the determined truncated normal distribution; and
calculating a multipath interference (MPI) value in the optical transmission line formed of the predetermined number of optical fiber pieces selected according to the random number, the MPI value being a value of multipath interference caused by the cutoff wavelength and the splice loss, using a mode dependent loss in a fundamental mode and a splice interval of the optical transmission line.