US2002113955A1PendingUtilityA1
Iterative approach to Stimulated Raman Scattering (SRS) error estimation
Priority: Dec 18, 2000Filed: Dec 13, 2001Published: Aug 22, 2002
Est. expiryDec 18, 2020(expired)· nominal 20-yr term from priority
G01N 21/65G01N 2021/655
43
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Claims
Abstract
Iterative approach to Stimulated Raman Scattering (SRS) error estimation in an optical fiber network comprised of determining a multi-channel SRS error value for each pairing of all possible pairings of all the channels by inputting measured channel power levels into a two-channel equation and further calculating the SRS error in a single fiber span for all channels by extending the two-channel equation in an iterative form for calculating the SRS error in a single fiber span for all channels. An embodiment of the invention further comprising determining for each channel over multiple fiber spans the amount of total SRS error value at every span based on the calculated SRS error value of its previous span to determine the SRS error accumulated over a multi-span network.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1 . An iterative method for Stimulated Raman Scattering (SRS) error estimation in an optical fiber network, the network characterized in that it comprises the infrastructure required to measure the power levels of all optical channels using a pilot tone monitoring technique, the method comprising the steps of:
(i) determining the multi-channel SRS error value for each pairing of all possible pairings of all the channels by inputting measured values of channel power levels into a two-channel equation substantially equal to: P s ( z ) = P s0 - α L [ ( 1 + P p0 g α ) + P p0 g α m cos ( ω t ) ] where α is the fiber attenuation and g is the Raman gain coefficient between channel P p and channel P s ; and (ii) calculating the SRS error in a single fiber span for all channels by extending the two-channel equation in an iterative form substantially equal to: for k=1:2 for i=1:Nch for j=1:Nch X(i)=X(i)+0.5*G*(j−i)*SpanP(j)*SpanTxP0; end SpanP(i)=SpanP(i)−X(i); end end to estimate the SRS error in a single span. where Nch=Number of channels SpanTxP 0 =Launch power into the fiber (equal power per wavelength is assumed) SpanP(j)=output power at channel j X(i)=SRS error in channel i G=g/α
2 . The method according to claim 1 , further comprising determining for each channel over multiple fiber spans the amount of total SRS error value at every span based on the calculated SRS error value of its previous span so as to determine the SRS error accumulated over a multi-span network, the method comprising an iterative form of the two-channel equation substantially equal to:
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3 . A system for Stimulated Raman Scattering (SRS) error estimation in an optical fiber network, the network characterized in that it comprises the infrastructure required to measure the power levels of all optical channels using a pilot tone monitoring technique, the system comprising:
means for determining the multi-channel SRS error value for each pairing of all possible pairings of all the channels by inputting measured values of channel power levels into a two-channel equation substantially equal to: P s ( z ) = P s0 e - α L [ ( 1 + P p0 g α ) + P p0 g α m cos ( ωt ) ] where α is the fiber attenuation and g is the Raman gain coefficient between channel P p and channel P s ; and means for calculating the SRS error in a single fiber span for all channels by extending the two-channel equation in an iterative form substantially equal to: for k=1:2 for i=1:Nch for j=1:Nch X(i)=X(i)+0.5*G*(j−i)*SpanP(j)*SpanTxP0; end SpanP(i)=SpanP(i)−X(i); end end to estimate the SRS error in a single span where Nch=Number of channels SpanTxP 0 =Launch power into the fiber (equal power per wavelength is assumed) SpanP(j)=output power at channel j X(i)=SRS error in channel i G=g/α
4 . The system according to claim 3 , further comprising a means for determining for each channel over multiple fiber spans the amount of total SRS error value at every span based on the calculated SRS error value of its previous span so as to determine the SRS error accumulated over a multi-span network, the system comprising an iterative form of the two-channel equation substantially equal to:
5 . A system for Stimulated Raman Scattering (SRS) error estimation in an optical fiber network, the network characterized in that it comprises the infrastructure required to measure the power levels of all optical channels using a pilot tone monitoring technique, the system comprising:
a network component having embedded computer readable code comprising a two-channel equation for determining a multi-channel SRS error value for each pairing of all possible pairings of all the channels by inputting the measured channel power levels into the equation, the equation substantially equal to P s ( z ) = P s0 e - α L [ ( 1 + P p0 g α ) + P p0 g α m cos ( ωt ) ] where α is the fiber attenuation and g is the Raman gain coefficient between channel P p and channel P s ; and a network component having embedded computer readable code comprised of an iterative extended form of the two-channel equation substantially equal to: for k=1:2 for i=1:Nch for j=1:Nch X(i)=X(i)+0.5*G*(j−i)*SpanP(j)*SpanTxP0; end SpanP(i)=SpanP(i)−X(i); end end to estimate the SRS error in a single span where Nch=Number of channels SpanTxP 0 =Launch power into the fiber (equal power per wavelength is assumed) SpanP(j)=output power at channel j X(i)=SRS error in channel i G=g/α
6 . The approach according to claim 5 , further comprising a network component having embedded computer readable code capable of determining for each channel over multiple fiber spans the amount of total SRS error value at every span based on the calculated SRS error value of its previous span so as to determine the SRS error accumulated over a multi-span network, the code comprised of an iterative form of the two-channel equation substantially equal to:
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