1、BRITISH STANDARD Fibre optic interconnecting devices and passive components - Basic test and measurement procedures Part 3. Examinations and measurements Section 9. Far-end crosstalk * * rn The European Standard EN 613003-9 : 1997 has the status of a British Standard ICs 33.180.20 NO COPYING WITHOUT
2、 BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BS EN 61300-3-9 : 1997 IEC 61300-3-9 1997 STDOBSI BS EN bL300-3-7-ENGL 1797 LbZqbb7 Ob25b57 143 m Amd. No. BS EN 61300-3-9 : 1997 Date Text affected This British Standard, having been prepared under the direction of the Elecrotechnical Sector Boar
3、d, was published under the authority of the Standards Board and comes into effect on 15 July 1997 O BSI 1997 National foreword This British standard is the English language version of EN 613W3-9 : 1997. It is identical with EC 613W3-9 : 1997. The UK participation in its preparation was entrusted by
4、Technical Committee EPM, Fibre optics, to SubcommitLee EPU86/2, Interconnecting devices and passive components, which has the responsibility to: - aid enquirem to understand the text; - present to the responsible intedonaliEuropean committee any enquiries on the interpretation, or proposals for chan
5、ge, and keep the UK interests informed; - monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this subcommittee cm be obtajned on request to its secrem. Cross-references The British Standards which implement international or E
6、uropean publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled International Stan - the reflection of light from the ends of fibre pigtails; - the spectral impurity of the light source such that far-end crosstalk at non-operational wavelength
7、s is measured (e.g. in WDM devices); - the light carried in cladding modes; - the accuracy of power meter at low light levels; - the fibre pigtail lengths since light can scatter (Rayleigh scattering) along the pigtails. 2 Apparatus The apparatus consists of the following elements: - STD*BSI BS EN b
8、1300-3-7-ENGL 1777 W Lb24bb7 Ub25bbL b74 Page 4 EN 61300-3-9 : 1997 2.1 Optical source S The source is pigtailed or connected to a launch optical fibre compatible with the input port of the device under test (DUT). It is also designedkonditioned such that cladding modes are suppressed at the output.
9、 For measurements of DUTs which are not inherently broadband in optical performance, the spectral output of the light source shall be characterized not only in the vicinity of the operating wavelength range (FWHM) but also in the region of the spectral tail. This requirement can be specified as “pow
10、er less than X dB below peak at wavelengths Y nm from peak output“ and can be achieved by use of in-line bandpass filters. The output power of the light source should also be sufficiently high to permit a large measurement dynamic range with the power meter used. 2.2 Temporary joint TJ This is a met
11、hod, device or mechanical fixture for temporarily aligning two fibre ends into a reproducible, low loss joint and polarization independent splicing. Typically, a fusion splice is used after the polarization adjuster since mechanical splices may exhibit some polarization sensitivity if the endfaces a
12、re not perpendicular to the fibre axis. The stability of the temporary joint shali be compatible with the required measurement precision. 2.3 Terminations T These terminations are components or techniques to suppress reflected light from the DUT output ports. Fibre terminations, marked T, shall have
13、 a high return loss. Three types 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 should have a return loss of at least 20 dB greater than the minim
14、um far- end crosstalk absolute value to be measured. 2.4 Detector D This should be a high dynamic range power meter. It should have an operational wavelength range consistent with the DUT and should also have the capability to zero the reference level. 3 Procedure 3.1 Connect the DUT to the light so
15、urce as shown in figure i. The source is connected to the selected input port of the DUT by means of a TJ where appropriate or by means of a connector in the case of a DUT fitted with a connector. The power meter is connected to a nominally through output port of the DUT (port “A) which is to be mea
16、sured for far-end crosstalk with another chosen output port nominally isolated from the previous one (port “B“). All other ports of the DUT are terminated (T). For WDMs the source shall transmit one wavelength to the corresponding output port and the far-end crosstalk shall be evaluated at the same
17、wavelength to another output port (port “B“), optimized at a different wavelength. In the figures 1 and 2 an example of measurement Set-ups for switches and WDMs is displayed. STDmBSI BS EN b1300-3-9-ENGL 1997 Lb24bb9 Ob25bb2 500 Page 5 EN 61300-3-9 : 1997 P port/ 1 “I I m TJ n T T JEC 268/97 Figure
18、 la - Measurement for a MxN switch 1 port“*“ /I u I IEC 26-7 * * m Figure 1 b - Measurement for a 1xN WDM Figure 1 - Measurement of Po 3.2 PO (dBrn) or, for WDMs, PO( Fax: i181 996 7400. IS1 offers members an individual updating service called PLUS which ensures that lubscribers automatically receiv
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