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35
EFFICIENCE OF USE THE SECOND WINDOW OF TRANSPARENCY
OF SINGLE-MODE OPTICAL FIBER
Edward L. Portnow,
Moscow technical University of communications and Informatics, Moscow, Russia,
DOI 10.24411/2072-8735-2018-10013
Keywords: single-mode optical fiber, the second window of transparency, chromatic dispersion, material and waveguide components of the chromatic dispersion, the length of the amplifying phase, the signal-to-noise ratio.
In a single-mode optical fiber chromatic dispersion limit at high speeds, the length of the amplification plot for a particular parameter of transmission -attenuation. To save this length should take a set of measures to compensate for chromatic dispersion in a line fiber for dispersion compensation, to include expansion joints in a two-stage amplifier circuit ,the use of distributed Raman amplification, to apply multi-level modulation scheme, phase diagrams solutions, etc. In all cases pursued the main goal to transfer a large amount of information over a long distance with a minimum number of intermediate amplifiers and with minimal losses. Attenuation coefficient of quartz optical fibers decrease due to the purity of the core of optical fiber and the offset of the transmission in the third window transparency, but in this case, the values of chromatic dispersion is large enough for standard and the most common optical fiber, is recommended by the International telecommunication Union ITU-T G-652
It is known that the largest value of the damping coefficient in a single-mode optical fiber G-652 in the second window of transparency at the wavelength of I3l0nm is equal to 0.35-0.4 dB/km, whereas in the third window of transparency it is of 0.17-0.2 dB/km.
To use the second transparency window in a standard optical fiber, where the wavelength cutoff value of chromatic dispersion becomes zero, it is necessary that the material and waveguide dispersion the chromatic components had opposite signs
The presented solutions allow you to identify and select the length of the amplification plot subject to chromatic dispersion in the second window of transparency of single-mode optical fiber.
Information about author:
Edward L. Portnow, Moscow technical University of communications and Informatics, head. the Department of NTS, Ph. D., Professor, Moscow, Russia
Для цитирования:
Портнов Э.Л. Эффективность использования второго окна прозрачности одномодового оптического волокна при высоких скоростях передачи // T-Comm: Телекоммуникации и транспорт. 2018. Том 12. №1. С. 65-67.
For citation:
Portnow E.L. (2018). Efficience of use the second window of transparency of single-mode optical fiber. T-Comm, vol. 12, no.1, pр. 65-67.
r I Л
According to [1] in a single-mode optical fiber chromatic dispersion limit at high speeds, the length of the amplification plot for a particular parameter of transmission - attenuation. To save this length should take a set of measures to compensate for chromatic dispersion in a line fiber for dispersion compensation, to include expansion joints in a two-stage amplifier circuit ,the use of distributed Raman amplification, to apply multi-level modulation scheme, phase diagrams solutions, etc. In all cases pursued the main goal to transfer a large amount of information over a long distance with a minimum number of intermediate amplifiers and with minimal losses. Attenuation coefficient of quart/ optical fibers decrease due to the purity of the core of optical fiber and the offset of the transmission in the third window transparency, but in this case, the values of chromatic dispersion is large enough for standard and the most common optical fiber, is recommended by the International telecommunication Union ITU-T G-652. But here, managed to reduce chromatic dispersion due to the creation of optical fibers with nonzero dispersion shifted G-655.
It is known that the largest value of the damping coefficient in a single-mode optical fiber G-652 in the second window of transparency at the wavelength of 13I0nm is equal to 0,35-0,4 dB/km» whereas in the third window of transparency it is 0,17-0,2 dB/km So for transport networks long-haul widely used third window transparency not only S G-652, but G-655, G-656.
To use the second transparency window in a standard optical fiber, where the wavelength cutoff value of chromatic dispersion becomes zero, you must;
- material dispersion should be zero at X =1310 nm - at this point the dispersion parameter becomes positive above and below this point is negative, in addition to material dispersion acts in the opposite waveguide dispersion, shifting point 1310 nm at 30-40 nm;
- material dispersion varies 1270-1290 nm for S with a quartz core and fluorine depresivno shell or quartz core with a mixture of GeOj and quartz sheath for the purpose of modifying the refractive index of the core or shell, that nl > n2 (nl is the core refractive index, n2 is the refractive index of the shell);
- waveguide dispersion is determined by the radius of the core is S and the indicator A = (n21 - n22)/2n21 — (nl-n2)/nl.
The main effect of waveguide dispersion is that it shifts the point of zero dispersion at 30-40 nm to the value of ¡310 nm and decreases the resulting characteristics of the material dispersion.
However, the dispersion does not completely disappear when 1) = 0 and X = 1310 nm, as is evident from the characteristics of the chromatic dispersion slope S, S (dispersion parameter second order).
According to (1)
D = -2jrc[yP, S = dD/d/, = (2;rc|W)2p3 +
+ (4ircA1)p1 ps/nm2.km
where = d|Vdco = d'p/dco5 At X,=1310nm p? = 0, S = p3
For a source with spectral width AX, the dispersion parameter is equal to D = S Aa ps/nm.km.
In this case the delay will be equal to: AT = L|S|(A>„)2.
The effect of chromatic dispersion on the bit rate is defined
BLISKAX)2 < I
The change in the dispersion of any type S in the transmitting window of transparency can be described by a three element approximation next to Taylor's changing around the Central wavelength
D(X,) = D0 is +C {A. is
S determines the slope of the dispersion characteristics; S = (l/2)d-D/d>,:, determines the curvature of the dispersion characteristics.
To account for the linearity of the dispersion characteristics determine the coefficient K.: K. = D/S.
Simultaneous compensation of dispersion D and slope S requires: Kd = Cd Kk = -Ck.
The waveguide dispersion for single mode fibers can also be estimated by the expression [2]:
Db = -(n2A/3Xo) x (10)7[0,080 +
+ 0.549(2.834- V)3] ps/nm.km
In this expression, A = (nl-n2)/nl
For the considered range of A = (1,46-1,457)/1,46 - 0,002.
V = ( 2ita//.)+ -Jn: 1 - n'2 normalized frequency.
For the second range of normalized frequency will be equal to
V = (2JI*4 MUl) Vl.462-1,4572 = 2,07
The solution of the waveguide dispersion will have a value in the second window of transparency
Db = -(1,457 x 0,002/3 x 1.31) x (10)7[0,08 +
+ 0,549(2,834-2,07f] = -2,96
The resulting value of the chromatic dispersion for singlemode optical fibre is in this case determined by the expression that in all considered cases will have a positive value and is less than the value of the material dispersion :
Dp = (Dm + DB )ps/nm.km - 3,245 - 2,96 = 0,285 ps/nm.km.
When determining the length of the amplifying section for chromatic dispersion it is necessary to use data at S recommendations G-652.
The General expression for the determination of chromatic dispersion.
D = (S/4XA - W), ps/nm.km.
The effective area S is determined by the expression.
Aeff= k-7i-w2-(X)
where k is a correction factor dependent on wavelength and the actual refractive index profile S. ¡t varies in the range of 0.95 <k< 1,03.
For large values of OSNR should have a large AelT, low n2 and low damping factor. These are the characteristics of fiber Corning SMF-28ULL (low attenuation and small n2) fiber G-652 fibre G-655 - Coming LEAF.
Increasing the speed of the transmission 4 times, reduce the energy capacity of the system at 6 dB, while maintaining the failure ratio 10-10
Typical OSNR required for different transmission rates in the direct detection at 10(-9) bit error rate are given in table
Empirical expression for the second window of transparency for the wavelength of I310nm will be:
OSNR{dB) = 60-101gN -NF - 1 OlgL + pout - I OlgM -K, where M is the number of channels, N is the number of amplifi-
T-Comm Tom 12. #1-2018
The result:
ers, L — lost one flight, NF-noise amplifier, pout is the output power of the amplifier, other factors.
If you reduce the noise of the amplifier and the signal-to-noise ratio at 3 dB length of the cascade of linear amplifiers is doubled, and in the nonlinear regime\2 times. The maximum line length is limited by amplifier noise, nonlinear effects and PMD S for each window of transparency and the transmission rate.
We define the dispersion length to accommodate the quadrature-phase modulation non-return to zero (NRZ) and pre-emptive error correction of the first generation (FEC).
Ld = T-b* d2m*(3,33 IgM)2* (Ql/Q0);/8pj. Get Ld - 41км,
With the loss of chromatic dispersion for 2 dB allowable length for dispersion in this case will be equal to 31km. There-lore, for dispersion compensation, use of 34 km of dispersive liber. In this case
L = 0,75Tb2*dm2*(3,33 lgM)2*<Q1/Q0)2/ 8(|32obLob +PiobkdLobkd)/( Lob+Lobkd)
The result is a solution by chromatic dispersion and its compensation on the line.
Knowing the length of the line and all the elements without PMD compensators define PMDI and PMD2.
PMDI - 3,7^дг(г2obLob + r~obkdLobk(i + Ът2 элементов,
L = 0,75*0,9 Tb2*d2m*<3,33 lgM)2*(Ql/Q0)2/ 8,l(|3jobLob + p2obkd Lobkd)/(Lob+Lobkd).
The final decision on the accounting and compensation of PMD was adopted after a preliminary full settlement and compensation line chromatic dispersion. In the differential mode delay equal to 0.5 Tb, the bit error rate(BWC) will be equal to 10(-3) and at a rate of 0.1 Tb BWC equal to 10 (-9).Therefore, to Optimally solve the problem of how to compensate chromatic and polarization mode dispersion.
1. Agrawal G.P. (2013). Nonlinear Fiber Optics. Moscow, 323 p.
2. Portnov E.L. (2009), Principles of primary networks, and optica/ cable lines. Moscow: "Hot line-Telecom", 2009. 544 p.
3. Kaminow I.P. (2013). Optical fiber Telecommunication VIA. Moscow: Academic Press. 595 p.
4. Agrawal G.P- (2002). Fiber-optic Communication Systems, Wiley-lnterscience. 580 p.
5. Grigoryan A.K., Portnov E.L. (2013). Algorithmic method of determining polarization mode dispersion on fiber-optic communication lines // t-Comm. №8, pp. 99-101.
6. Portnov E.L. (2012). Optic cables, their installation and size. Textbook for high schools. Moscow: Hot line-Telecom, 2012. 448 p.
References
ЭФФЕКТИВНОСТЬ ИСПОЛЬЗОВАНИЯ ВТОРОГО ОКНА ПРОЗРАЧНОСТИ ОДНОМОДОВОГО ОПТИЧЕСКОГО ВОЛОКНА ПРИ ВЫСОКИХ СКОРОСТЯХ ПЕРЕДАЧИ
Портнов Эдуард Львович, Московский технический университет связи и информатики, Москва, Россия, [email protected] Аннотация
Передать большой объем информации на большое расстояние с минимальным количеством промежуточных усилителей и с минимальными потерями - главная цель. Это обеспечивается коэффициентом затухания оптического волокна. Коэффициент затухания кварцевых оптических волокон уменьшают за счет чистоты сердцевины оптического волокна и смещения передачи в третье окно прозрачности, но в этом случае значения хроматической дисперсии достаточно большое для стандартного и самого распространенного оптического волокна, рекомендованного Международным союзом электросвязи ITU-T G-652. Во втором окне прозрачности значение коэффициента затухания в рассматриваемом одномодовом оптическом волокне на длине волны 1310 нм равно 0,35-0,4 дБ/км, тогда как в третьем окне прозрачности оно составляет
0.17.0,2 дБ/км. Для использования второго окна прозрачности в стандартном оптическом волокне, где при длине волны отсечки значение хроматической дисперсии обращается в ноль и она не ограничивает длину регенерационного участка, при этом необходимо ,чтобы материальная и волноводная составляющие хроматической дисперсии имели противоположные знаки. Для сохранения этой длины следует принимать комплекс мероприятий, чтобы скомпенсировать хроматическую дисперсию: включить в линию волокна для компенсации дисперсии, включить компенсаторы в двухкаскадной схеме усилителей ,использовать распределенное рамановское усиление, применить многоуровневую схему модуляции, использовать фазовые схемы решений .Представленные решения позволяют определить и выбрать длину усилительного участка с учетом хроматической дисперсии во втором окне прозрачности одномодового оптического волокна.
Ключевые слова: одномодовое оптическое волокно, второе окно прозрачности, хроматическая дисперсия, материальная и волноводная составляющие хроматической дисперсии, длина усилительного участка, отношение сигнал/шум.
Литература
1. Agrawal G.P. Nonlinear Fiber Optics. Moscow, 2013. 323 p.
2. Портнов ЭЛ. Принципы построения первичных сетей и оптические кабельные линии связи. М.: Горячая линия-Телеком, 2009. 544 с.
3. Kaminow I.P. Optical fiber Telecommunication VIA. Academic Press 2013. 595 p.
4. Agrawal G.P. Fiber-optic Communication Systems, Wiley-Interscience 2002. 580 p.
5. Портнов ЭЛ. Оптические кабели связи, их монтаж и измерение. Учебное пособие для вузов. М.: Горячая линия-Телеком, 2012. 448 с.
6. Григорьян А.К., Портнов Э.Л. Алгоритмическая методика определения поляризационной модовой дисперсии на волоконно-оптической линии связи // T-Comm: Телекоммуникации и транспорт. 2013. №8. С. 99-101.
Информация об авторе:
Эдуард Львович Портнов, Московский технический университет связи и информатики, зав. кафедрой НТС, д.т.н., профессор, Москва, Россия
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