US2008007719A1PendingUtilityA1
Method for Increasing Accuracy of Measurement of Mean Polarization Mode Dispersion
Est. expiryDec 29, 2023(expired)· nominal 20-yr term from priority
G01M 11/336H04B 10/2569G01M 11/331
47
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Claims
Abstract
The present invention provides a method for increasing the accuracy of measurement of mean differential group delay (DGD) from the polarization mode dispersion (PMD) in optical fiber. The method includes a systematic correction to mean-square DGD measured with any conventional mean to minimize systematic error caused by finite source bandwidth. The method further includes a systematic correction to the measurement of mean DGD and mean square DGD from statistics of the second-order PMD (SOPMD) obtained with frequency domain PMD-measuring apparatus. The probability density function (PDF) of either the vector or scalar SOPMD is applied, depending on which quantity is measured. The systematic correction is made to minimize the systematic error in estimating mean DGD, caused by finite source bandwidth, to achieve a two-fold reduction of the measurement variance equivalent to doubling the source bandwidth.
Claims
exact text as granted — not AI-modified1 . A method of improving service in an optical fiber system including generating a value for a characteristic of a differential group delay associated with a length of optical fiber comprising the steps of:
measuring a polarization mode dispersion vector as a function of frequency using a frequency-domain polarization mode dispersion measurement apparatus; calculating a second-order polarization mode dispersion vector {right arrow over (τ)} ω as a function of frequency by calculating a derivative with respect to frequency of the polarization mode dispersion vector; calculating a mean of a square root of a magnitude of the second-order polarization mode dispersion vector {right arrow over (τ)} ω to obtain a first result; multiplying a proportionality coefficient A 2 of the second-order polarization mode dispersion vector {right arrow over (τ)} ω by the first result to calculate the mean differential group delay where τ and are in units of seconds 2 , ω is in units of radians/second and A 2 is dimensionless; and generating a value of
2 . The method of claim 1 , wherein the first result is calculated according to
〈
τ
->
ω
1
/
2
〉
,
wherein |{right arrow over (τ)} ω | represents the magnitude of the second-order polarization mode dispersion vector; and the mean differential group delay is calculated in accordance with the following equation:
A
2
〈
τ
->
ω
1
/
2
〉
=
〈
τ
〉
,
where |{right arrow over (τ)} 107 | is in units of seconds 2 .
3 . The method of claim 2 , wherein A 2 is substantially equal to 1.37.
4 . The method of claim 1 , wherein the frequency-domain polarization mode dispersion measurement apparatus is at least one of a polarimetric device and a fixed analyzer device.
5 . The method of claim 1 , wherein the length of optical fiber is at least one of a single fiber link and a fiber route.
6 . A method of improving service in an optical fiber system including generating a value for a characteristic of a differential group delay associated with a length of optical fiber comprising the steps of:
measuring a magnitude of a polarization mode dispersion vector |τ ω | as a function of frequency, using a frequency-domain polarization mode dispersion measurement apparatus, the magnitude of the polarization mode dispersion vector |τ ω | being a scalar differential group delay; calculating a frequency derivative of the scalar differential group delay ⅆ τ -> ⅆ ω from the magnitude of the polarization mode dispersion vector to obtain a first result, the frequency derivative of the scalar differential group delay being a scalar second-order polarization mode dispersion function; multiplying a proportionality coefficient B 2 by the first result to calculate the mean differential group delay where B 2 is dimensionless, τ and are in units of seconds, ω is in units of radians/second, and |τ ω | and ⅆ τ -> ⅆ ω are in units of seconds 2 ; and generating a value of
7 . The method of claim 6 , wherein the first result is calculated according to
〈
ⅆ
τ
->
ⅆ
ω
1
/
2
〉
,
where |τ| is in units of seconds, and the mean differential group delay is calculated in accordance with the following equation:
B
2
〈
ⅆ
τ
->
ⅆ
ω
1
/
2
〉
=
〈
τ
〉
.
8 . The method of claim 7 , wherein B 2 is substantially equal to 2.64.
9 . The method of claim 6 , wherein the frequency-domain polarization mode dispersion measurement apparatus comprises one of a polarimetric device and a fixed analyzer device.
10 . The method of claim 6 , wherein the length of optical fiber is at least one of a single optical fiber link and an optical fiber route.
11 . A method of improving service in an optical fiber system including generating a value for a characteristic of a differential group delay associated with a length of optical fiber comprising the steps of:
measuring a polarization mode dispersion vector as a function of frequency, using a frequency-domain polarization mode dispersion measurement apparatus; calculating a second-order polarization mode dispersion vector {right arrow over (τ)} ω as a function of frequency by calculating a derivative of the polarization mode dispersion vector with respect to frequency ω; calculating the mean of the magnitude of the second-order polarization mode dispersion vector |{right arrow over (τ)} ω | to obtain a first result; multiplying a proportionality coefficient A 1 by the first result to calculate the mean square differential group delay τ 2 RMS , where A 1 is dimensionless, |{right arrow over (τ)} ω | and τ 2 RMS are in units of seconds 2 ; and generating a value of τ 2 RMS .
12 . The method of claim 11 , wherein the first result is obtained according to
〈
τ
->
ω
〉
,
and the mean square differential group delay is calculated in accordance with the following equation:
A
1
〈
τ
->
ω
〉
=
τ
RMS
2
.
13 . The method of claim 12 , wherein A 1 is substantially equal to 2.02.
14 . The method of claim 11 , wherein the frequency-domain polarization mode dispersion measurement apparatus comprises at least one of a polarimetric device and a fixed analyzer device.
15 . The method of claim 11 , wherein the length of optical fiber is at least one of single optical fiber link and an optical fiber route.
16 . A method of improving service in an optical fiber system including generating a value for a characteristic of a differential group delay associated with a length of optical fiber comprising the steps of:
measuring a magnitude of a polarization mode dispersion vector as a function of frequency using a frequency-domain polarization mode dispersion measurement apparatus, the magnitude of the polarization mode dispersion vector being a scalar differential group delay; calculating a frequency derivative of the scalar differential group delay from the magnitude of the polarization mode dispersion vector to obtain a first result, the frequency derivative of the scalar differential group delay ⅆ τ -> ⅆ ω being a scalar second-order polarization mode dispersion function; multiplying a proportionality coefficient B 1 by the first result to calculate the mean square differential group delay τ 2 RMS , where B 1 is dimensionless, and ⅆ τ -> ⅆ ω is in units of seconds 2 ; and generating a value of τ 2 RMS .
17 . The method of claim 16 , wherein the first result is calculated according to
〈
ⅆ
τ
->
ⅆ
ω
〉
,
and the mean square differential group delay is calculated in accordance with the following equation:
B
1
〈
ⅆ
τ
->
ⅆ
ω
〉
=
τ
RMS
2
.
18 . The method of claim 17 , wherein B 1 is substantially equal to 6.80.
19 . The method of claim 16 , wherein the frequency-domain polarization mode dispersion measurement apparatus comprises at least one of a polarimetric device and a fixed analyzer device.
20 . The method of claim 16 , wherein the length of optical fiber is at least one of a single optical fiber link and an optical fiber route.
21 . A method of improving service in an optical fiber system including generating a value for a characteristic of a differential group delay associated with a length of optical fiber comprising the steps of:
deriving a first mean in accordance with the following equation: A 2 〈 τ -> ω 1 2 〉 = 〈 τ 〉 ; deriving a second mean in accordance with the following equation: B 2 〈 ⅆ τ -> ⅆ ω 1 2 〉 = 〈 τ 〉 ; deriving a linear equation of the first mean and the second mean to calculate a combined mean wherein a sum of coefficients of the linear equation is substantially equal to one; and generating a value ofJoin the waitlist — get patent alerts
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