IEC TR 61282-7:2003

Fibre optic communication system design guides - Part 7: Statistical calculation of chromatic dispersion

Provides methods of representing the process statistics of the chromatic dispersion of optical fibres and related components that may be combined in a link. The presence of chromatic dispersion can induce distortions in signals leading to bit errors depending on; source spectral width; source chirp; bit period; distance. Has the status of a Technical report.

General Information

• Status: Published
• Publication Date: 20-Jan-2003
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 33.180.01 - Fibre optic systems in general
• Technical Committee: SC 86C - Fibre optic systems and active devices
• Drafting Committee: WG 1 - TC 86/SC 86C/WG 1
• Current Stage: PPUB - Publication issued
• Start Date: 31-Jan-2003
• Completion Date: 21-Jan-2003

Standards Content (Sample)

TECHNICAL IEC
REPORT
TR 61282-7
First edition
2003-01
Fibre optic communication system design guides –
Part 7:
Statistical calculation of chromatic dispersion
Guides de conception des systèmes de communications
à fibres optiques –
Partie 7:
Calcul statistique de la dispersion chromatique
Reference number
IEC/TR 61282-7:2003(E)
Publication numbering
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60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.
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TECHNICAL IEC
REPORT
TR 61282-7
First edition
2003-01
Fibre optic communication system design guides –
Part 7:
Statistical calculation of chromatic dispersion
Guide de conception des systèmes de communications
à fibres optiques –
Partie 7:
Calcul statistique de la dispersion chromatique
 IEC 2003  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
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For price, see current catalogue

– 2 – TR 61282-7  IEC:2003(E)
CONTENTS
FOREWORD . 3
1 Scope . 4
2 Normative references. 4
3 Characterisation of chromatic dispersion coefficient versus wavelength . 5
4 Characterisation of chromatic dispersion coefficient statistics versus wavelength . 6
5 Calculation of the concatenation statistics for a single population of optical fibres. 9
6 Generalisation of concatenation statistics for multiple populations –
including components. . 10
Figure 1 – Distribution of dispersion parameters. 6
Figure 2 – Histogram of values at 1 560 nm . 7
Figure 3 – Histogram of values at 1 530 nm . 7
Figure 4 – Average dispersion coefficient versus wavelength . 8
Figure 5 – Standard deviation of dispersion coefficient versus wavelength . 8
Figure 6 – Fibre average . 11
Figure 7 – Fibre standard deviation . 11
Figure 8 – Dispersion compensator average. 12
Figure 9 – Dispersion compensator standard deviation. 12
Figure 10 – Combined three sigma limits. 13
Table 1 – Computed values at two selected wavelengths . 10

TR 61282-7  IEC:2003(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE OPTIC COMMUNICATION SYSTEM DESIGN GUIDES –
Part 7: Statistical calculation of chromatic dispersion
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International
Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two
organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this technical report may be the subject of
patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC 61282-7, which is a technical report, has been prepared by subcommittee 86C: Fibre
optic systems and active devices, of IEC technical committee 86: Fibre optics.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
86C/429/DTR 86C/468/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
2009-12. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
– 4 – TR 61282-7  IEC:2003(E)
FIBRE OPTIC COMMUNICATION SYSTEM DESIGN GUIDES –
Part 7: Statistical calculation of chromatic dispersion
1 Scope
This part of IEC 61282 is a guideline providing methods of representing the process statistics
of the chromatic dispersion of optical fibres and related components that may be combined in
a link.
Chromatic dispersion (ps/nm) is the derivative, with respect to wavelength, of the group delay
(ps) induced by the spectral content of light propagating through an optical element or fibre.
Chromatic dispersion is normally a function of wavelength and can be either positive (group
delay increasing with wavelength) or negative (group delay decreasing with wavelength).
The presence of chromatic dispersion can induce distortions in signals leading to bit errors
depending on
– source spectral width;
– source chirp;
– bit period;
– distance.
In addition, chromatic dispersion is interactive with the effects of non-linear optical effects and
second order polarisation mode dispersion (PMD). The above system impairments are beyond
the scope of this technical report.
When different components or fibres are combined, the chromatic dispersion of the
combination is the total of the chromatic dispersion values of the individuals, on a wavelength-
by-wavelength basis. A section with high chromatic dispersion will be balanced by sections
with lower values. The variation in the total dispersion of links will therefore be dependent on
the distributions of the products that are used in the link. This document provides methods to
calculate the distribution statistics of concatenated links based on information on the
distributions of different fibre or component populations.
NOTE In the clauses that follow, examples are given for particular fibre and component types. These examples
are not necessarily broadly representative.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60793-1-42: Optical fibres – Part 1-42: Measurement methods and test procedures –
Chromatic dispersion
IEC 60793-2-50: Optical fibres – Part 2-50: Product specifications – Sectional specification for
class B single-mode fibres
ITU-T Recommendation G.652: Characteristics of a single-mode optical fibre cable
ITU-T Recommendation G.655: Characteristics of a non-zero dispersion shifted single-mode
optical fibre cable
TR 61282-7  IEC:2003(E) – 5 –
ITU-T Recommendation G.671: Transmission characteristics of optical components and
subsystems
ITU-T Recommendation G.691: Optical interfaces for single-channel STM-64, STM-256 and
other SDH systems with optical amplifiers
3 Characterisation of chromatic dispersion coefficient versus wavelength
This clause outlines the characterisation of dispersion as a function of wavelength – for a
given wavelength range. This function is often represented as a formula that includes
parameters that can vary from fibre to fibre for a given fibre design. Characterisations of these
formulas should give an indication of the wavelength range over which the formula applies.
Extrapolation beyond these ranges can result in error.
For optical fibre, chromatic dispersion coefficient, D, can vary with wavelength, λ, according to
a variety of formula types that are found in IEC 60793-1-42. The simplest is the linear
representation which has just two parameters, zero-dispersion wavelength, λ , and zero-
dispersion slope, S , as:
D()λ = S (λ − λ ) (ps/nm ⋅⋅⋅⋅km) (1)
0 0
Measurements are based either on fitting differential group delays (DGD) or by fitting the
integral to the measured group delay.
Other forms defined in 60793-1-42 are the three-term Sellmeier (Equation (2)), and the five-
term Sellmeier (Equation (3)). Note that for the five-term Sellmeier, parameters, C , different
j
from the zero-dispersion wavelength and slope must be fitted.
 
S λ  λ 
0  0 
D()λ = 1−  (2)
 
 
4 λ
 
 
−3 3 −5
D()λ = 2C λ − 2C λ + 4C λ − 4C λ (3)
1 2 3 4
For components, similar types of expressions can be used to characterise the chromatic
dispersion value, d, as a function of wavelength. For components, however, the units are most
often given as ps/nm (unadjusted for length). [The use of the term “coefficient,” for fibre
indicates a length normalisation.]

– 6 – TR 61282-7  IEC:2003(E)
Even for the products for which the linear representation of Equation (1) is appropriate for
each individual fibre, the combination of the distributions of the zero-dispersion wavelength
and slope will normally not lead to a very clear understanding of the distribution of chromatic
dispersion. Figure 1 shows such a combined distribution that illustrates a correlation between
the dispersion parameters.
0,100
0,095
0,090
0,085
0,080
0,075
0,070
0,065
0,060
0,055
0,050
1 560 1 562 1 564 1 566 1 568 1 570 1 572 1 574 1 576 1 578
Lambda-0  nm
IEC  3207/02
Figure 1 – Distribution of dispersion parameters
4 Characterisation of the chromatic dispersion coefficient
statistics versus wavelength
This clause outlines the technique used to characterise the distribution of a single population
of fibres. Similar approaches can be applied to components.
The fibre distribution shown in Figure 1 was intended for use in the wavelength range of
1 530 nm to 1 560 nm – a B4 type fibre (ITU-T G.655), see IEC 60793-2-50. The chromatic
dispersion values for the lower end of this range are affected more by the variation of slope
values for high zero-dispersion wavelength than for low zero dispersion wavelength. The
combined contributions are therefore difficult to evaluate without some other means.
The characterisation methodology suitable for use in concatenation st
...