1、BRITISH STANDARDBS EN 61744:2005Calibration of fibre optic chromatic dispersion test sets The European Standard EN 61744:2005 has the status of a British StandardICS 33.180.01g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3
2、g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 61744:2005This British Standard was published under the authority of the Standards Policy and Strategy Committee on 13 February 2006 BSI 13 February 2006ISBN 0 580 47700 2National forewordThis British Standard is the of
3、ficial English language version of EN 61744:2005. It is identical with IEC 61744:2005. It supersedes BS EN 61744:2001 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee GEL/86, Fibre optics, which has the responsibility to:A list of organizations represen
4、ted on this committee can be obtained on request to its secretary.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or
5、by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard does not of itself confer immuni
6、ty from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in th
7、e UK.Summary of pagesThis document comprises a front cover, an inside front cover, the EN title page, pages 2 to 54, an inside back cover and a back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publicationAmd. No. Date
8、CommentsEUROPEAN STANDARD EN 61744 NORME EUROPENNE EUROPISCHE NORM December 2005 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels
9、 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 61744:2005 E ICS 33.180.01 Supersedes EN 61744:2001English version Calibration of fibre optic chromatic dispersion test sets (IEC 61744:2005) Etalonnage des ensembles dessai de
10、 la dispersion chromatique des fibres optiques (CEI 61744:2005) Kalibrierung von Prfaufbauten zur Bestimmung der chromatischen Dispersion (IEC 61744:2005) This European Standard was approved by CENELEC on 2005-09-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which
11、 stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European S
12、tandard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the na
13、tional electrotechnical committees of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United
14、 Kingdom. Foreword The text of document 86/236/FDIS, future edition 2 of IEC 61744, prepared by IEC TC 86, Fibre optics, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61744 on 2005-09-01. This European Standard supersedes EN 61744:2001. The principal change is the
15、addition of reference to wavelength in vacuum. This reference is critical for accurate production, measurement and sale of products in the emerging market applications of fibre optics such as dense wavelength division multiplexing (DWDM) systems. The following dates were fixed: latest date by which
16、the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2006-07-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2008-09-01 Annex ZA has been added by CENELEC. _ Endorsement notice The te
17、xt of the International Standard IEC 61744:2005 was approved by CENELEC as a European Standard without any modification. _ EN 61744:2005 2 3 EN 61744:2005 CONTENTS 0 Introduction . 5 0.1 Chromatic dispersion in optical fibres 5 0.2 Chromatic dispersion (CD) test sets 5 0.3 Overview of calibration pr
18、ocedures described in this standard. 5 1 Scope 7 2 Normative references 7 3 Terms and definitions 8 4 Calibration14 4.1 Rationale for calibration of CD test sets .14 4.2 Preparation for calibration16 4.3 Calibration procedure 17 4.4 Calibration checking procedure18 5 Wavelength calibration procedure
19、.18 5.1 General .18 5.2 Discrete sources19 5.3 Tunable sources19 5.4 Uncertainties and reporting22 6 Delay dispersion calibration procedure .22 6.1 General .22 6.2 Equipment and preparation22 6.3 Calibration procedure 24 6.4 Uncertainties and reporting25 7 Calibration checking procedure.25 7.1 Gener
20、al .25 7.2 Equipment and preparation26 7.3 Procedure .26 7.4 Uncertainties and reporting27 7.5 Generation of infant reference fibre27 8 Documentation .28 8.1 Specifications, measurement data and uncertainties 28 8.2 Traceability information .29 Annex A (normative) Mathematical basis30 Annex B (norma
21、tive) Assessment of operational uncertainties 35 Annex C (informative) Chromatic dispersion.43 Annex D (informative) CD test set calibration compensation .47 Annex E (informative) Vacuum and air wavelength .50 Annex ZA (normative) Normative references to international publications with their corresp
22、onding European publications54 EN 61744:2005 4 Bibliography .53 Figure 1 Typical calibration chain for CD test sets . 9 Figure 2 Typical optical delay line artefact for CD test set delay calibration.23 Figure 3 Typical differential delay dispersion simulator for CD test set calibration .24 Figure 4
23、Reference fibre comparison27 Figure 5 Generation of a reference fibre.27 Figure A.1 Deviation and uncertainty type B, and how to replace both by an appropriately larger uncertainty.32 Figure C.1 Schematic diagram of a CD test set 44 Figure E.1 Dispersion and air and vacuum wavelength .51 5 EN 61744:
24、2005 0 Introduction 0.1 Chromatic dispersion in optical fibres Chromatic dispersion is the variation with optical light wavelength of the light propagation delay time in a length of fibre. This variation can cause bandwidth limitation in the fibre when used to transmit communication signals. For a m
25、ore detailed explanation, refer to Annex C and IEC 60793-1-1. 0.2 Chromatic dispersion (CD) test sets CD test sets are used to measure the chromatic dispersion properties of optical fibres and typically comprise an optical source of known wavelength(s), a fibre light input coupling and output coupli
26、ng means, optical detection means, and electronic or optical means of determining the optical delay or dispersion at the source wavelength. There are several variants each requiring slightly different calibration techniques. Refer to Annex C for further details. In general, all CD test sets produce
27、an output of fibre delay or dispersion versus the light wavelength, typically in graphical form. Thus, wavelength constitutes the x-axis and delay or dispersion the y-axis. 0.3 Overview of calibration procedures described in this standard The requirement to calibrate the CD test set, traceable to kn
28、own standards, is essential for quality control in fibre optic production, fibre research and similar activities. This standard describes the detailed procedures used to establish calibration of a CD test set. Calibration of a CD test set is established by applying known artefacts or standards (them
29、selves calibrated to reference standards) to the CD test set, measuring its response and adjusting (correcting) the CD test set to achieve results that match the standards used. In this way the CD test set results will be brought to close agreement with other CD test sets also calibrated in the mann
30、er described in this standard. Primarily the artefacts or standards used are as follows: a) wavelength artefact(s) used to calibrate the light source wavelength(s) used by the CD test set. This is to establish the correct excitation wavelength for the system (the x-axis) in order that the correct de
31、lay or dispersion (the y-axis) be determined subsequently; b) delay or dispersion artefact(s) used to calibrate the delay or dispersion response of the CD test set (the y-axis). Calibration can only be carried out using these artefacts. After a calibration has been completed, a calibration period is
32、 defined over which the CD test set is deemed to remain calibrated. At the end of this period, it would be necessary to establish if the CD test set calibration requires updating (changing); this can be performed using the artefact described above, or by use of a known standard fibre (reference fibr
33、e) whose chromatic dispersion is known. This is referred to as calibration checking. The fibre forms a stable source of known dispersion and may be used as a simple dispersion artefact. If it is found that the calibration has not changed within the required uncertainty limits, then it is possible to
34、 simply extend the calibration period again by a defined amount. EN 61744:2005 6 If, however, it is found that the CD test set measurement results have changed significantly compared to the user requirements (i.e. the test set has drifted), then calibration using the artefacts (if not already carrie
35、d out at this time) should be carried out and the calibration renewed. The above rationale ensures that the CD test set calibration is only ever performed using known standards (artefacts), but that if the CD test set is sufficiently stable over the calibration period selected, then a simple check o
36、f calibration can suffice to ascertain this and to (justify) allow the extension of the calibration period. The extension can be repeated indefinitely over many calibration periods, provided the CD test set continues to remain within uncertainty limits over the entire set of calibration periods. In
37、order to be considered calibrated and in conformance with this standard, a CD test set must have its calibration adjusted based on comparison to artefacts for the primary parameters of wavelength and delay dispersion. In all cases, this calibration of primary parameters is necessary, but may or may
38、not be sufficient, to ensure calibration of the CD test set to the required uncertainty. In addition, it may be necessary to also confirm or compensate the calibration state of a CD test set using a calibrated reference fibre. The CD test set calibration compensation is explained more fully in Annex
39、 D. It should be noted that use of a calibrated reference fibre alone is not sufficient to ensure calibration of a CD test set. It should also be noted that if a calibrated CD test set undergoes calibration compensation using a calibrated reference fibre, the scope and extent of its calibration is l
40、imited to the conditions used at the time of calibration compensation (i.e. wavelength, fibre type, loss regime, etc.) Care should be exercised that test sets calibrated and compensated in this manner are used only within the appropriate limits of their calibration extent. The adjustments required t
41、o effect compensation on one set of wavelengths for one fibre type may increase the uncertainty of measurement of other fibre types with different minimum dispersion wavelengths. In this document, the reference medium for wavelength and the velocity of light is assumed to be in normal air. However,
42、since the velocity of light in air (or rather, the refractive index of air) is dependent on barometric pressure, humidity and temperature, it is sometime advantageous to reference the velocity of light in vacuum, and hence define the refractive index =1,0000000. This leads to a slight shift in the w
43、avelength scale of the order of 0,3 nm to 0,4 nm depending on the wavelength value, between the so-called “wavelength in air” (as assumed in this document) and the wavelength in vacuum, also called “vacuum wavelength”. Vacuum wavelength is typically used where very accurate dispersion control is req
44、uired such as in long-haul or submarine fiber cable systems. CD test sets for measuring fibers used in these applications are typically calibrated to vacuum wavelength, e.g. using a wavemeter, or by mathematical correction of results obtained with an internal air wavelength calibration. In order tha
45、t the user be familiar with the conversion from air wavelength and the mathematical corrections involved, an informative annex, Annex E, is provided. 7 EN 61744:2005 CALIBRATION OF FIBRE OPTIC CHROMATIC DISPERSION TEST SETS 1 Scope This International Standard provides standard procedures for the cal
46、ibration of optical fibre chromatic dispersion (CD) test sets. It also provides procedures to perform calibration checking on CD test sets whereby an extension to the test set calibration period may be obtained. This standard is applicable to all types of CD test sets, with the exception that measur
47、ements on multimode optical fibres are excluded. The purpose of this standard is to define a standard procedure for calibrating optical fibre chromatic dispersion (CD) test sets. The detailed calibration steps used vary according to the measurement technique used in the CD test set. Whilst it is ack
48、nowledged that chromatic dispersion also occurs in multimode fibre and this fibre may be measured on many CD test sets, this standard will restrict discussion to single mode fibre measurements only. The purpose of the procedures outlined in this standard is to focus manufacturers and users of CD tes
49、t sets toward the reduction of measurement uncertainty in chromatic dispersion determination in optical fibres under all applicable conditions. The procedures apply to calibration laboratories and to the manufacturers or users of CD test sets for the purpose of a) calibrating CD test sets; b) setting specifications of CD test sets; c) extending the calibration period of an already calibrated CD test set. Use of the procedures also allows correct evaluation of CD test set uncertainty, relative and trace
