1、BRITISH STANDARD BS EN 61300-3-20:2002 IEC 61300-3-20:2001 Incorporating Corrigendum No. 1 Fibre optic interconnecting devices and passive components Basic test and measurement procedures Part 3-20: Examinations and measurements Directivity of fibre optic branching devices The European Standard EN 6
2、1300-3-20:2001 has the status of a British Standard ICS 33.180.20 BS EN 61300-3-20:2002 This British Standard, having been prepared under the direction of the Electrotechnical Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 14
3、 March 2002 BSI 7 October 2002 ISBN 0 580 39088 8 National foreword This British Standard is the official English language version of EN 61300-3-20:2001, including Corrigendum March 2002. It is identical with IEC 61300-3-20:2001. The UK participation in its preparation was entrusted by Technical Com
4、mittee GEL/86, Fibre optics, to Subcommittee GEL/86/2, Interconnecting devices and passive components, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. From 1 January 1997, all IEC publications have the number 6000
5、0 added to the old number. For instance, IEC 27 has been renumbered as IEC 60027-1. For a period of time during the change over from one numbering system to the other, publications may contain identifiers from both systems. Cross-references The British Standards which implement international or Euro
6、pean publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include a
7、ll the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible European committee any enquiries on the interpr
8、etation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 5 and a back cover. The BSI copyri
9、ght date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments 13872 Corrigendum No. 1 7 October 2002 Change to date of publication in EN forewordIncorporating Corrigendum March 2002 -2002-1110Page2 EN61300320:2001 rocnItar
10、opC gniorregiudnM ma02 hcr20 2002-11-01 2 613-00-320 CEI:0210(E) FIBRE OPTIC INTERCONNECTING DEVICES AND PASSIVE COMPONENTS BASIC TEST AND MEASUREMENT PROCEDURES Part 3-20: Examinations and measurements Directivity of fibre optic branching devices 1 Scope The purpose of this part of IEC 61300 is to
11、measure the directivity of light between channels of a multiport non-wavelength-selective MxN fibre optic branching device. The directivity is defined as the fraction of the light that goes from an input path to another input optical path, normally isolated from the previous one. 2 General descripti
12、on The measurement procedure of the directivity entails a comparison between two optical power level measurements. The reference power level is the optical power measured from a fibre which is connected to an optical source. The directivity is the measured optical power at an input port that is norm
13、ally optically isolated from the reference input when it is connected to the optical source. The directivity is then given by the ratio of these two power level measurements, expressed in decibels (dB). Since directivity levels of concern for practical use of fibre optic branching devices can be ver
14、y small, even of the order of 70 dB, the relevant measurement can be degraded by several factors. Therefore this procedure is designed to either circumvent these factors, or to point them out so that adequate care and choice of test apparatus can be taken. Factors which can degrade a measurement of
15、directivity include: coupling of ambient light into measurement channels; reflection of light from the ends of fibre pigtails; light carried in cladding modes; accuracy of the power meter at low light levels; fibre pigtail lengths since light can scatter (Rayleigh scattering) along the pigtails. 3 A
16、pparatus The apparatus consists of: 3.1 Optical source (S) The source is pigtailed or connected to a launch optical fibre compatible with the input port of the branching device under test (BD). It is also designed/conditioned so that cladding modes are suppressed at the output. For measurements of B
17、Ds which are not inherently broad band in optical performance, the bandwidth of the light source shall fall within the BD operative wavelength range; in particular the emitted power of the source in the BD band shall be greater than the power source level outside the same band by at least 10 dB. Mor
18、eover the output power of the light source shall also be high enough to permit a dynamic range of at least 10 dB over the minimum directivity to be measured, with the power meter used. Page3 EN61300320:2001163-00-320 CEI:0210(E) 3 3.2 Temporary joint (TJ) This is a method, device, or mechanical fixt
19、ure for temporarily aligning two fibre ends into a reproducible, low loss joint and polarisation independent splicing. Typically, a fusion splice is used after the polarisation adjuster since mechanical splices may exhibit some polarisation sensitivity if the end faces are not perpendicular to the f
20、ibre axis. The stability of the temporary joint shall be compatible with the required measurement precision. 3.3 Terminations (T) These terminations are components or techniques to suppress reflected light from the BD output ports. Fibre terminations, marked T, shall have a high return loss. Three t
21、ypes of terminations are suggested: angled fibre ends; the application of an index matching material to the fibre end; attenuation of the fibre, for example with a mandrel wrap. The fibre termination shall have a return loss such that the reflections generated from all the terminated ports give a to
22、tal return loss at least 20 dB greater than the minimum directivity to be measured. 3.4 Detector (D) This should be a high dynamic range power meter. It should have an operational wavelength range consistent with the BD and should also have the capability to “zero“ the reference level. 4 Procedure 4
23、.1 Connect the light source to the detector (D), as shown in figure 1(a), by means of a TJ where appropriate or by means of a connector in the case of a connectorized BD. Figure 1 Measurement of directivity T P 0 D TJ S (a) Port “A” T TJ S BD (b) T Port “B” P 1 N output D T M input IEC 396/01 Page4
24、EN61300320:2001 4 613-00-320 CEI:0210(E) 4.2 Turn on the light source (S) and allow sufficient time for it to stabilize. Measure and record P 0(dBm) as in figure 1(a). 4.3 Connect the light source (S) to input port “A”, by means of a TJ or by a connector in the case of a connectorised BD, and connec
25、t the detector D to port “B“, which is normally isolated from the port “A”. Terminate the remaining input ports and the output ports of the BD, as shown in figure 1(b). 4.4 Measure and record the output power from port “B“ as P 1(dBm). 4.5 The directivity for this combination of ports is given by: D
26、irectivity = P 1 P 0(dB); 4.6 Repeat 4.2 4.5 for other input/isolated port combinations as specified. 5 Details to be specified The following details, as applicable, shall be specified in the detail specification. 5.1 Input port combinations of the BD to be measured 5.2 Characteristics of source (S)
27、 5.3 Temporary joint (TJ) type and characteristics 5.4 Power meter (D) specifications 5.5 Performance requirements for directivity for each specified port (input/isolated) combination 5.6 Deviations from this test procedure _ Page5 EN61300320:2001BS EN 61300-3-20:2002 IEC 61300-3-20:2001 BSI 389 Chi
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