IEC TR 62627-02:2010

IEC/TR 62627-02 ®
Edition 1.0 2010-06
TECHNICAL
REPORT
colour
inside
Fibre optic interconnecting devices and passive components –
Part 02: Report of round robin test results on SC plug style fixed attenuators

IEC/TR 62627-02:2010(E)
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IEC/TR 62627-02 ®
Edition 1.0 2010-06
TECHNICAL
REPORT
colour
inside
Fibre optic interconnecting devices and passive components –
Part 02: Report of round robin test results on SC plug style fixed attenuators

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XA
ICS 33.180.10 ISBN 978-2-88912-025-3
– 2 – TR 62627-02 © IEC:2010(E)
CONTENTS
FOREWORD.4
1 Scope.6
2 Normative references .6
3 Background .6
4 Conclusions.7
5 Test results .8
5.1 Round robin test results of SC/PC plug style attenuator .8
5.1.1 SC/PC plug style attenuator test samples .8
5.1.2 Test method .8
5.1.3 Test laboratories involved in RRT on SC/PC plug style attenuators .8
5.1.4 Measurement results of SC/PC plug style attenuators .9
5.1.5 Summary of attenuation measurements results of SC/PC plug style
attenuators .14
5.1.6 Random mating performance with grade B connectors .16
5.1.7 Overview of PDL results for SC/PC plug style attenuators .18
5.2 Measurement results for SC/APC plug style attenuators.18
5.2.1 SC/APC plug style attenuator test samples.18
5.2.2 Test method .19
5.2.3 Test laboratories involved in RRT on SC/APC plug style attenuators .19
5.2.4 Measurement results of SC/APC plug style attenuators .19
5.2.5 Summary of attenuation measurements results of SC/APC plug style
attenuators .25
5.2.6 Overview of PDL results for SC/APC plug style attenuators .30
6 Mechanical interface issues with SC plug style attenuators .31
Annex A Individual test laboratory results of SC/PC attenuators .33
Annex B Individual test laboratory results of SC/APC plug style attenuators .46

Figure 1 – 15 dB attenuators – All lab results – Common reference .9
Figure 2 – 5 dB attenuators – All lab results.11
Figure 3 – 1 dB attenuators – All lab results.13
Figure 4 – Spectral scan of attenuators.17
Figure 5 – Overview of PDL measurements results for SC/PC plug style attenuators .18
Figure 6 – 1 dB attenuators – All lab results – Common reference .20
Figure 7 – 5 dB attenuators – All lab results – Common reference .22
Figure 8 – 15 dB attenuators – All lab results.24
Figure 9 – Overview of PDL measurements results for SC/APC style attenuators .30
Figure 10 – SC plug style attenuator dimensions .31
Figure 11 – Possible configurations for plug style attenuator.31
Figure A.1 – Laboratory A results with 2 nm resolution (LED light source) .34
Figure A.2 – Laboratory A results with 2 nm resolution (LASER light source) .35
Figure A.3 – Laboratory B results with 2 nm resolution .36
Figure A.4 – Laboratory C results with 2 nm resolution .38
Figure A.5 – Laboratory D results with 2 nm resolution .39
Figure A.6 – Laboratory E results with 2nm resolution .40

TR 62627-02 © IEC:2010(E) – 3 –
Figure A.7 – Laboratory E results with 10 nm resolution.41
Figure A.8 – Laboratory F results with 2 nm resolution.42
Figure A.9 – Laboratory F results with 10 nm resolution.43
Figure A.10 – Laboratory G results with 2 nm resolution .44
Figure A.11 – Laboratory G results with 10 nm resolution .45
Figure B.1 – ‘Laboratory A’ results – spectral measurements .47
Figure B.2 – ‘Laboratory A’ results – LED measurements.48
Figure B.3 – ‘Laboratory B’ results – spectral measurements .49
Figure B.4 – ‘Laboratory B’ results – LED measurements.50
Figure B.5 – Laboratory C results – spectral measurements .51
Figure B.6 – ‘Laboratory C’ results – LED measurements .52
Figure B.7 – ‘Laboratory D’ results – spectral measurements.53
Figure B.8 – ‘Laboratory D’ results – LED measurements .54
Figure B.9 – ‘Laboratory E’ results – spectral measurements .55
Figure B.10 – ‘Laboratory E’ results – LED measurements.56

Table 1 – Pass/fail result .15
Table 2 – Pass/fail result with relaxed performance critera .16
Table 3 – Pass/fail result of original specification.26
Table 4 – Pass/fail result with relaxed optical performance critera .27
Table 5 – Pass/fail result of original specification.27
Table 6 – Pass/fail result with relaxed optical performance critera .28
Table 7 – LED measurements results at 1310 nm (green colour = pass) .29
Table 8 – LED measurements results at 1550 nm (green colour = pass) .29
Table 9 – SC plug style attenuator behaviour analysis for different working configurations .32
Table A.1 – PDL measurements from Laboratory A.35
Table A.2 – PDL measurements from Laboratory B.37
Table A.3 – PDL measurements from laboratory E.39
Table A.4 – PDL measurements from laboratory E.41
Table A.5 – PDL measurements from Laboratory F.43
Table A.6 – PDL measurements from laboratory G .45
Table B.1 – PDL measurements from ‘Laboratory A’ .48
Table B.2 – PDL measurements from ‘Laboratory B’ .50
Table B.3 – PDL measurements from ‘Laboratory C’ .52
Table B.4 – PDL measurements from ‘Laboratory D’ .54
Table B.5 – PDL measurements from ‘Laboratory E’ .56

– 4 – TR 62627-02 © IEC:2010(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE OPTIC INTERCONNECTING
DEVICES AND PASSIVE COMPONENTS –

Part 02: Report of round robin test results
on SC plug style fixed attenuators

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
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data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC 62627-02, which is a technical report, has been prepared by subcommittee 86B: Fibre
optic interconnecting devices and passive components, of IEC technical committee 86: Fibre
optics.
TR 62627-02 © IEC:2010(E) – 5 –
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
86B/2941/DTR 86B/2993/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.
A list of all parts of the IEC 62627 series, published under the general title Fibre optic interconnecting
devices and passive components, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 6 – TR 62627-02 © IEC:2010(E)
FIBRE OPTIC INTERCONNECTING
DEVICES AND PASSIVE COMPONENTS –

Part 02: Report of round robin test results
on SC plug style fixed attenuators

1 Scope
This part of IEC 62627 reports the measurement results of two round robin test programs
each carried out on SC/PC and SC/APC plug style fixed attenuators. The work was initiated at
Cenelec TC 86BXA in June 2003 in order to get a clear understanding on the accuracy and
repeatability of the spectral attenuation loss measurements on fixed attenuators.
Out of these results recommendations are made for attenuation tolerance values that can be
used in the performance standards.
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 61300-3-2, Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-2: Examinations and measurements – Polarization
dependent loss in a single-mode fibre optic device
IEC 61300-3-4, Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-4: Examinations and measurements – Attenuation
IEC 61300-3-7, Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-7: Examinations and measurements – Wavelength
dependence of attenuation and return loss of single mode components
IEC 61754-4, Fibre optic connector interfaces – Part 4: Type SC connector family
IEC 61755-1, Fibre optic connector optical interfaces – Part 1: Optical interfaces for single
mode non-dispersion shifted fibres – General and guidance
3 Background
While preparing a product specification for SC plug style fixed attenuators, members of the
Cenelec TC86BXA reported unexpected large and wavelength dependent variations in the
attenuation. Also poor performance was seen in the mating durability test.
At the same time, several customer complaints were reported from operators that used plug
style attenuators on active transceivers.
In order to understand these issues a round robin test was organised among various test
laboratories.
TR 62627-02 © IEC:2010(E) – 7 –
4 Conclusions
4.1 Attenuation measurements with reference connectors
The attenuation measurement results of the SC plug style fixed attenuators with reference
connectors reported in Clause 5 show larger than expected variations for spectral attenuation,
especially in the 1 310 nm window. When taking the performance criteria used to purchase
these fixed attenuators being:
– attenuators with nominal attenuation value ≤ 5 dB: tolerance level of 0,5 dB.
– attenuators with nominal attenuation value > 5 dB: tolerance level of 10 % on nominal
value.
Only 9 of the 18 SC/PC attenuators would pass all the 7 participating laboratories and only 12
of the 18 SC/APC attenuators would pass 5 test laboratories.
Physical phenomena like modal noise interference largely influence the repeatability of results,
even when the measurements are performed with reference connectors and reference
adapters.
Wideband source measurements with LED source and power meter proved high uniformity of
results obscuring the unwanted effects of modal noise. All the attenuators passed the tight
criteria of measurements against reference plugs when the attenuation measurements were
made according to IEC 61300-3-4 with LED light source at 1 310 nm and 1 550 nm.
Following realistic performance criteria for the wavelength dependent attenuation measured
with reference connectors are therefore suggested:
– attenuators with nominal attenuation value ≤ 5 dB: tolerance level of 0,75 dB.
– attenuators with nominal attenuation value > 5 dB: tolerance level of 15 % on nominal
attenuation value.
4.2 Attenuation measurements with grade B connectors
In random mating conditions using connectors with attenuation grade B (as defined in
IEC 61755-1), the variations in wavelength dependent attenuation becomes much larger,
especially in the 1 310 nm region. Spectral loss values up to 19 dB are reported for a 15 dB
attenuator. When taking the performance requirements used to purchase these fixed
attenuators, the pass/fail results for random mated measurements would allow only 6 of the
18 attenuators to pass the 5 participating test laboratories.
4.3 Polarisation dependent loss
PDL measurement results also show a larger variation of values for measurements in the
1310 nm window.
4.4 Mechanical interface
The non reproducibility of the spectral attenuation measurements indicated possible
mechanical interface issues. Thorough analysis of mechanical behaviour of “plug-attenuator-
adapter-plug” and “transceiver-attenuator-plug” configurations was done. The relevant
dimensions H and H of parameter H in the type SC connector mechanical interface standard
m f
IEC 61754-4 were checked in worst case situations. Main conclusion is that there is no room
for additional tolerances in the existing interface standard for the SC connector and adapter.
SC plug style attenuators should be made with fixed values for parameters H and H without

f m
any tolerance range.
The functional performance of the SC plug style attenuators can not be assured at this time.
With the dimensions and tolerances in the current IEC 61754-4 mechanical interface

– 8 – TR 62627-02 © IEC:2010(E)
documents for the SC connector and adapter, it is not possible to make a plug style
attenuator which guarantees intermateability in all applications.
Additionally, active transceivers with fixed ferrule should never be connected with a plug
style attenuator made according to the relevant IEC 61754-4 mechanical interface.
5 Test results
5.1 Round robin test results of SC/PC plug style attenuator
5.1.1 SC/PC plug style attenuator test samples
In total 18 SC/PC plug style fixed attenuators were collected for this round robin test:
– attenuators with nominal attenuation of 15 dB (labelled 1, 2, 3, 4, 5 and 6)
– attenuators with nominal attenuation of 5 dB (labelled 7, 8, 9, 10, 11 and 12)
– 6 attenuators with nominal attenuation of 1 dB (labelled 13, 14, 15, 16, 17 and 18)
The attenuators were obtained from various suppliers. The operating principle of all devices is
based on the use of attenuating fibre.
The performance grade of these attenuators was defined as:
Operating wavelength range: 1 260 nm – 1 360 nm and 1 460 nm – 1 580 nm
Attenuation tolerance: 0,5 dB for attenuators ≤ 5 dB, 10 % of nominal attenuation
value for attenuators > 5 dB
5.1.2 Test method
5.1.2.1 Spectral attenuation loss (according to IEC 61300-3-7)
For the ease of the data processing the measured values were reported for the discrete
wavelengths: 1 260, 1 280, 1 310, 1 330, 1 360, 1 460, 1 490, 1 520, 1 550, 1 570 and
1 580 nm. The spectral width was 2 nm. Some laboratories also reported values with a
spectral width of 10 nm. Each lab performed the measurements with 2 sets of reference
connectors and adapters:
– measurements with common reference connectors and adapter (same references for all
the test laboratories),
– measurements with own lab reference connectors and adapter.
Uncertainty of each loss measurement at the above mentioned wavelength range was better
than 0,1 dB.
5.1.2.2 Polarisation dependent loss (PDL) (according to IEC 61300-3-2, option 1)
PDL was measured at 1 310 nm and 1 550 nm, with common reference plugs. Selected
measurements method was “all states method”. The accuracy of each PDL measurement was
better than 0,1 dB.
5.1.3 Test laboratories involved in RRT on SC/PC plug style attenuators
The following laboratories were involved in this round robin test (in alphabetic order):
– Adamant Kogyo Co., Ltd. (Japan)
– Diamond (Switzerland)
– Huber and Suhner (Switzerland)
– Telekomunikacja Polska (Poland)

TR 62627-02 © IEC:2010(E) – 9 –
– TILab (Telecom Italia Laboratories) (Italy)
– Tyco Electronics-AMP (the Netherlands)
– Tyco Electronics-Raychem (Belgium)
5.1.4 Measurement results of SC/PC plug style attenuators
An overview of all spectral attenuation measurements per attenuator is given in Figures 1, 2
and 3. The detailed measurement results for each individual laboratory can be found in
Annex A.
Attenuator 1 - Common ref
17.5
17.00
16.00
16.5
15.00
14.00
1250 1300 1350 1400 1450 1500 1550 1600
15.5
b) Average ± 2σ of attenuator 1
1250 1350 1450 1550
Wavelenght (nm)
a) Attenuator 1 – Common reference
Attenuator 2 - Common ref
16.8
16.3
15.8
17.00
16.00
15.3
15.00
14.00
14.8
13.00
1250 1300 1350 1400 1450 1500 1550 1600
14.3
d) Average ± 2σ of attenuator 2
13.8
1250 1350 1450 1550
Wavelenght (nm)
c) Attenuator 2 – Common reference
Attenuator 3 - Common ref
16.5
17.00
15.5
16.00
15.00
14.5
14.00
14 1250 1300 1350 1400 1450 1500 1550 1600
13.5 f) Average ± 2σ of attenuator 3
1250 1350 1450 1550
Wavelenght (nm)
e) Attenuator 3 – Common reference

Figure 1 – 15 dB attenuators – All lab. results – Common reference
Attenuation (dB) Attenuation (dB) Attenuation (dB)

– 10 – TR 62627-02 © IEC:2010(E)

Attenuator 4 - Common ref
16.5
15.5 17.00
16.00
15.00
14.5
14.00
1250 1300 1350 1400 1450 1500 1550 1600
h) Average ± 2σ of attenuator 4
13.5
1250 1350 1450 1550
Wavelenght (nm)
g) Attenuator 4 – Common reference
Attenuator 5 - Common ref
16.5
16.00
15.5
15.00
14.00
14.5
13.00
14 1250 1300 1350 1400 1450 1500 1550 1600

13.5
j) Average ± 2σ of attenuator 5
1250 1350 1450 1550
Wavelenght (nm)
i) Attenuator 5 – Common reference
Attenuator 6 - Common ref
16.5
15.50
15.5
14.50
14.5
13.50
14 1250 1300 1350 1400 1450 1500 1550 1600
13.5
l) Average ± 2σ of attenuator 6
1250 1350 1450 1550
Wavelenght (nm)
k) Attenuator 6 – Common reference

Figure 1 – 15 dB attenuators – All lab. results – Common reference (continued)

Attenuation (dB) Attenuation (dB) Attenuation (dB)

TR 62627-02 © IEC:2010(E) – 11 –
Attenuator 7 - Common ref
5.8
5.6
5.70
5.40
5.4
5.10
5.2
4.80
4.50
1250 1300 1350 1400 1450 1500 1550 1600
4.8
4.6 b) Average ± 2σ of attenuator 7
1250 1350 1450 1550
Wavelenght (nm)
a) Attenuator 7 – Common reference
Attenuator 8 - Common ref
6.2
5.8
6.00
5.6
5.50
5.4 5.00
4.50
5.2
1250 1300 1350 1400 1450 1500 1550 1600
d) Average ± 2σ of attenuator 8
4.8
1250 1350 1450 1550
Wavelenght (nm)
c) Attenuator 8 – Common reference
Attenuator 9
5.8
5.6
5.70
5.40
5.4
5.10
5.2
4.80
5 4.50
1250 1300 1350 1400 1450 1500 1550 1600
4.8
4.6 f) Average ± 2σ of attenuator 9
1250 1350 1450 1550
Wavelenght (nm)
e) Attenuator 9 – Common reference

Figure 2 – 5 dB attenuators – All lab. results
Attenuation (dB) Attenuation (dB) Attenuation (dB)

– 12 – TR 62627-02 © IEC:2010(E)
Attenuator 10 - Common ref
5.2
4.8 5.40
5.10
4.6
4.80
4.4
4.50
4.2
4.20
1250 1300 1350 1400 1450 1500 1550 1600

3.8
h) Average ± 2σ of attenuator 10
1250 1350 1450 1550
Wavelenght (nm)
g) Attenuator 10 – Common reference
Attenuator 11 - Common ref
5.8
6.50
5.6
6.00
5.4
5.50
5.2
5.00
4.50
1250 1300 1350 1400 1450 1500 1550 1600
4.8
4.6
j) Average ± 2σ of attenuator 11
1250 1350 1450 1550
Wavelenght (nm)
i) Attenuator 11 – Common reference
Attenuator 12 - Common ref
6.2
5.8
6.50
5.6
6.00
5.4 5.50
5.00
5.2
4.50
1250 1300 1350 1400 1450 1500 1550 1600
4.8
4.6
l) Average ± 2σ of attenuator 12
1250 1350 1450 1550
Wavelenght (nm)
k) Attenuator 12 – Common reference

Figure 2 – 5 dB attenuators – All lab. results (continued)

Attenuation (dB) Attenuation (dB)
Attenuation (dB)
TR 62627-02 © IEC:2010(E) – 13 –
Attenuator 13 - Common ref
1.5
1.3
1.60
1.1
1.20
0.80
0.9
0.40
1250 1300 1350 1400 1450 1500 1550 1600
0.7
b) Average ± 2σ of attenuator 13
0.5
1250 1350 1450 1550
Wavelenght (nm)
a) Attenuator 13 – Common reference
Attenuator 14 - Common ref
1.5
1.3
1.60
1.1
1.20
0.80
0.9
0.40
0.7 1250 1300 1350 1400 1450 1500 1550 1600

d) Average ± 2σ of attenuator 14
0.5
1250 1350 1450 1550
Wavelenght (nm)
c) Attenuator 14 – Common reference
Attenuator 15 - Common ref
1.5
1.3
1.60
1.1
1.20
0.80
0.9
0.40
0.7 1250 1300 1350 1400 1450 1500 1550 1600
f) Average ± 2σ of attenuator 14
0.5
1250 1350 1450 1550
Wavelenght (nm)
e) Attenuator 14 – Common reference

Figure 3 – 1 dB attenuators – All lab. results
Attenuation (dB) Attenuation (dB)
Attenuation (dB)
– 14 – TR 62627-02 © IEC:2010(E)
Attenuator 16 - Common ref
1.7
1.5
1.60
1.3
1.20
0.80
1.1
0.40
1250 1300 1350 1400 1450 1500 1550 1600
0.9
h) Average ± 2σ of attenuator 14
0.7
1250 1350 1450 1550
Wavelenght (nm)
g) Attenuator 14 – Common reference
Attenuator 17 - Common ref
1.5
1.3
1.60
1.1
1.20
0.80
0.9
0.40
0.7 1250 1300 1350 1400 1450 1500 1550 1600
j) Average ± 2σ of attenuator 14
0.5
1250 1350 1450 1550
Wavelenght (nm)
i) Attenuator 14 – Common reference
Attenuator 18 - Common ref
1.7
1.5
1.60
1.3
1.20
0.80
1.1
0.40
0.9
1250 1300 1350 1400 1450 1500 1550 1600
l) Average ± 2σ of attenuator 14
0.7
1250 1350 1450 1550
Wavelenght (nm)
k) Attenuator 14 – Common reference

Figure 3 – 1 dB attenuators – All lab. results (continued)
5.1.5 Summary of attenuation measurements results of SC/PC plug style attenuators
When taking the performance criteria used to purchase these fixed attenuators, the pass/fail
results would allow only 9 of the 18 attenuators to pass all 7 laboratories (see Table 1):
– attenuators with nominal attenuation value ≤ 5 dB: tolerance level of 0,5 dB.
– attenuators with nominal attenuation value > 5 dB: tolerance level of 10 % on nominal
value.
Attenuation (dB) Attenuation (dB) Attenuation (dB)

TR 62627-02 © IEC:2010(E) – 15 –
Table 1 – Pass/fail result
Overview pass/fail with reference connectors and adapter
Laboratories
A B C D E F G
Attenuator
FAILED FAILED FAILED
1 Pass Pass Pass Pass
2 Pass Pass Pass Pass Pass Pass Pass
3 Pass Pass Pass Pass Pass Pass Pass
4 Pass Pass Pass Pass Pass Pass Pass
5 Pass Pass Pass Pass Pass Pass Pass
6 Pass Pass Pass Pass Pass Pass Pass
7 Pass Pass Pass Pass Pass Pass Pass
FAILED FAILED FAILED FAILED
8 Pass Pass Pass
9 Pass Pass Pass Pass Pass Pass Pass
10 FAILED FAILED Pass Pass Pass FAILED FAILED
FAILED FAILED FAILED FAILED
11 Pass Pass Pass
12 FAILED FAILED Pass FAILED FAILED FAILED FAILED
13 Pass Pass Pass Pass Pass Pass Pass
14 Pass Pass Pass Pass Pass Pass Pass
15 Pass Pass Pass Pass Pass Pass Pass
16 Pass Pass FAILED Pass Pass Pass Pass
17 Pass Pass Pass Pass Pass Pass FAILED
18 Pass Pass FAILED Pass Pass Pass Pass

Relaxed performance criteria for the spectral attenuation were suggested:
– attenuators with nominal attenuation value ≤ 5 dB: tolerance level of 0,75 dB.
– attenuators with nominal attenuation value > 5 dB: tolerance level of 15 % on nominal
value.
With these relaxed performance criteria 13 of the 18 attenuators in this round robin test would
have passed all 7 laboratories tests with the reference connectors and adapter (2 nm
resolution). Results are listed in Table 2.

– 16 – TR 62627-02 © IEC:2010(E)
Table 2 – Pass/fail result with relaxed performance critera
Overview pass/fail with reference connectors and adapter
Laboratories
A B C D E F G
Attenuator
1 FAILED Pass Pass Pass Pass Pass Pass
2 Pass Pass Pass Pass Pass Pass Pass
3 Pass Pass Pass Pass Pass Pass Pass
4 Pass Pass Pass Pass Pass Pass Pass
5 Pass Pass Pass Pass Pass Pass Pass
6 Pass Pass Pass Pass Pass Pass Pass
7 Pass Pass Pass Pass Pass Pass Pass
FAILED
8 Pass Pass Pass Pass Pass Pass
9 Pass Pass Pass Pass Pass Pass Pass
10 FAILED Pass Pass Pass Pass Pass Pass
FAILED FAILED
11 Pass Pass Pass Pass Pass
12 Pass Pass Pass FAILED FAILED FAILED Pass
13 Pass Pass Pass Pass Pass Pass Pass
14 Pass Pass Pass Pass Pass Pass Pass
15 Pass Pass Pass Pass Pass Pass Pass
16 Pass Pass Pass Pass Pass Pass Pass
17 Pass Pass Pass Pass Pass Pass Pass
18 Pass Pass Pass Pass Pass Pass Pass

Any specification for this technology of plug style attenuators that states tighter tolerance
values than given in the above mentioned relaxed criteria should be considered as non
realistic at this moment.
5.1.6 Random mating performance with grade B connectors
One of the test laboratories provided the full spectral attenuation plots of the fixed plug style
attenuators measured with reference connectors and measured with random selected
connectors (connectors according to IEC 61755-1 attenuation grade B and return loss
grade 2). Measurement results are shown in Figure 4.

TR 62627-02 © IEC:2010(E) – 17 –

Reference leads and reference adapter Random connectors and random adapter
Spectral scan of 15 dB attenuators Spectral scan of 15dB attenuators
Reference lead & common adapter Random lead & adapter
1 1
13 2
12 4
1250 1300 1350 1400 1450 1500 1550 1600 1650
1250 1300 1350 1400 1450 1500 1550 1600 1650
Wavelength (nm) Wavelength (nm)

a) 15 dB attenuators – Reference
b) 15 dB attenuators – Random selected
connectors
connectors
Spectral scan of 5dB attenuators Spectral scan of 5dB attenuators
Reference lead & common adapter Random lead & adapter
7 7
6.5 6.5
5.5
5.5
4.5
4.5
3.5
3.5
1250 1300 1350 1400 1450 1500 1550 1600 1650
1250 1300 1350 1400 1450 1500 1550 1600 1650
Wavelength (nm)
Wavelength (nm)
c) 5 dB attenuators – Reference
d) 5 dB attenuators – Random selected
connectors connectors
Spectral scan of 1dB attenuators Spectral scan of 1dB attenuators
Reference lead & common adapter Random pigtail + adapter
1.5
1.9
1.4
1.3 1.7
1.2
1.5
1.1
1.3
0.9 1.1
0.8 14
15 0.9
0.7 16
17 17
0.7
0.6
0.5
0.5
1250 1300 1350 1400 1450 1500 1550 1600 1650
1250 1300 1350 1400 1450 1500 1550 1600 1650
Wavelength (nm) Wavelength (nm)

e) 1 dB attenuators – Reference
f) 1 dB attenuators – Random selected
connectors
connectors
Figure 4 – Spectral scan of attenuators
Physical phenomena like modal noise interference are largely influencing the repeatability of
the random mating results.
Attenuation (dB)
Attenuation (dB)
Attenuation (dB)
Attenuation (dB) Attenuation (dB) Attenuation (dB)

– 18 – TR 62627-02 © IEC:2010(E)
5.1.7 Overview of PDL results for SC/PC plug style attenuators
PDL measurement results also show a larger variation of values for measurements in the
1 310 nm window (see Figure 5). The detailed measurement results for each individual test
laboratory can be found in Annex A.
Laboratory A
PDL at 1310 nm �
1.00
Laboratory B
�
Laboratory D
�
0.80
Laboratory E
�
Laboratory F
�
Laboratory G
0.60 �
0.40
0.20
0.00
1 2 3 4 5 6 7 8 9 1011 1213 14 1516 1718
attenuator
a) PDL at 1 310 nm
PDL at 1550 nm
1.00
0.80
0.60
0.40
0.20
0.00
1 2 3 4 5 6 7 8 9 1011 1213 1415 1617 18
attenuator
b) PDL at 1 550 nm
Figure 5 – Overview of PDL measurements results for SC/PC plug style attenuators
5.2 Measurement results for SC/APC plug style attenuators
5.2.1 SC/APC plug style attenuator test samples
In total 18 SC/APC plug style fixed attenuators were collected for this round robin test:
– 6 attenuators with nominal attenuation of 1 dB (labelled 1, 2, 3, 4, 5, and 6)
– 6 attenuators with nominal attenuation of 5 dB (labelled 7, 8, 9, 10, 11, and 12)
– 6 attenuators with nominal attenuation of 15 dB (labelled 13, 14, 15, 16, 17, and 18)
PDL values (dB) PDL values (dB)

TR 62627-02 © IEC:2010(E) – 19 –
The attenuators were obtained from various suppliers. The attenuating principle of all devices
is based on the use of high attenuating fibre.
The performance grade of these attenuators is defined as:
Operating wavelength range: 1260 nm-1360 nm and 1460 nm-1580 nm
Attenuation tolerance: 0,5 dB for attenuators ≤ 5 dB, 10 % of nominal
attenuation value for attenuators > 5 dB
5.2.2 Test method
5.2.2.1 General
All participating test laboratories measured spectral attenuation and polarisation dependent
loss for each attenuator. For the sake of decreasing uncertainty all measurement procedures
were specified in necessary details.
5.2.2.2 Spectral attenuation loss (according to IEC 61300-3-7)
The measured values were reported for the discrete wavelengths in the full spectral range
from 1 260 nm to 1 650 nm with 5 nm steps. The spectral width was set at 2 nm. To minimize
uncertainty of measured results, measuring equipment specifications and measurement
procedures were clearly stated. Each test laboratory performed the measurements with 2 sets
of plugs and adapters:
• measurements with common reference plugs and adapter (the same references for all
the test laboratories),
• measurements with own ‘IEC 61755-1 Grade B’ plugs and own adapter.
Estimated measurement uncertainty did not exceed 0,1 dB for the whole measurement range.
5.2.2.3 Attenuation at 1 310 nm and 1 550 nm measured with LED source and power
meter (according to IEC 61300-3-4)
The measurements were performed with common reference plugs at two wavelengths 1 310
nm and 1 550 nm. The accuracy of each attenuation measurement was better than 0,1 dB.
5.2.2.4 Polarisation dependent loss (PDL) (according to IEC 61300-3-2 option 1).
PDL was measured at 1 310 nm and 1 550 nm, with common reference plugs. Selected
measurements method was “all states method”. The accuracy of each PDL measurement was
better than 0,1 dB.
5.2.3 Test laboratories involved in RRT on SC/APC plug style attenuators
The following laboratories were involved in this round robin test (in alphabetical order):
– Adamant Kogyo Co., Ltd. (Japan)
– Diamond (Switzerland)
– Huber and Suhner (Switzerland)
– Telekomunikacja Polska (Poland)
– Tyco Electronics (The Netherlands)
5.2.4 Measurement results of SC/APC plug style attenuators
Figures 6, 7 and 8 show the overview of all the spectral attenuation measurements for 1 dB,
5 dB and 15 dB attenuators respectively. The detailed measurement results for each
individual laboratory can be found in Annex B.

– 20 – TR 62627-02 © IEC:2010(E)

Attenuator 1 - common reference plugs
Attenuator 1 - average ± 2σ
2,0
2,0
1,5
lab 1
1,5
lab 2
lab 3
lab 4
lab 5
1,0
1,0
0,5
0,5
1250 1350 1450 1550 1650
1250 1350 1450 1550 1650
Wavelength [nm]
Wavelength [nm]
b) Average ± 2σ of attenuator 1
a) Attenuator 1 – Common reference plugs
Attenuator 2 - common reference plugs
Attenuator 2 - average ± 2σ
2,0
2,0
1,5
lab 1
1,5
lab 2
lab 3
lab 4
lab 5
1,0
1,0
0,5
0,5
1250 1350 1450 1550 1650
1250 1350 1450 1550 1650
Wavelength [ nm]
Wavelength [nm]
d) Average ± 2σ of attenuator 2
c) Attenuator 2 – Common reference plugs
Attenuator 3 - common reference plugs
Attenuator 3 - average ± 2σ
2,0
2,0
1,5
lab 1
1,5
lab 2
lab 3
lab 4
lab 5
1,0
1,0
0,5
0,5 1250 1350 1450 1550 1650
1250 1350 1450 1550 1650
Wavelength [ nm]
Wavelength [nm]
f) Average ± 2σ of attenuator 3
e) Attenuator 3 – Common reference plugs

Figure 6 – 1 dB attenuators – All lab. results – Common reference
Attenuation [dB] Attenuation [dB] Attenuation [dB]
Attenuation [dB]
Attenuation [ dB] Attenuation [ dB]

TR 62627-02 © IEC:2010(E) – 21 –
Attenuator 4 - common reference plugs
± 2σ
Attenuator 4 - average
2,0
2,0
1,5
lab 1
1,5
lab 2
lab 3
lab 4
lab 5
1,0
1,0
0,5
0,5 1250 1350 1450 1550 1650
1250 1350 1450 1550 1650
Wavelength [nm]
Wavelength [nm]
h) Average ± 2σ of attenuator 4
g) Attenuator 4 – Common reference plugs
Attenuator 5 - common reference plugs
Attenuator 5 - average ± 2σ
2,0
2,0
1,5
lab 1
1,5
lab 2
lab 3
lab 4
lab 5
1,0
1,0
0,5
0,5 1250 1350 1450 1550 1650
1250 1350 1450 1550 1650
Wavelength [nm]
Wavelength [nm]
j) Average ± 2σ of attenuator 5
i) Attenuator 5 – Common reference plugs
Attenuator 6 - common reference plugs
Attenuator 6 - average ± 2σ
2,0
2,0
1,5
lab 1
1,5
lab 2
lab 3
lab 4
lab 5 1,0
1,0
0,5
1250 1350 1450 1550 1650
0,5
Wavelength [nm]
1250 1350 1450 1550 1650
Wavelength [nm]
l) Average ± 2σ of attenuator 6
k) Attenuator 6 – Common reference plugs

Figure 6 – 1 dB attenuators – All lab. results – Common reference (continued)
Attenuation [dB] Attenuation [dB] Attenuation [dB]
Attenuation [dB] Attenuation [dB] Attenuation [dB]

– 22 – TR 62627-02 © IEC:2010(E)
Attenuator 7 - common reference plugs
± 2σ
Attenuator 7 - average
6,0
6,0
5,5
5,5
lab 1
lab 2
lab 3
5,0
5,0
lab 4
lab 5
4,5
4,5
4,0
4,0 1250 1350 1450 1550 1650
1250 1350 1450 1550 1650
Wavelength [nm]
Wavelength [nm]
b) Average ± 2σ of attenuator 7
a) Attenuator 7 – Common reference plugs
Attenuator 8 - common reference plugs
Attenuator 8 - average ± 2σ
6,0
6,0
5,5
5,5
lab 1
lab 2
lab 3
5,0
5,0
lab 4
lab 5
4,5
4,5
4,0
4,0 1250 1350 1450 1550 1650
1250 1350 1450 1550 1650
Wavelength [nm]
Wavelength [nm]
d) Average ± 2σ of attenuator 8
c) Attenuator 8 – Common reference plugs
Attenuator 9 - common reference plugs
Attenuator 9 - average ± 2σ
6,0
6,0
5,5
5,5
lab 1
lab 2
lab 3
5,0
5,0
lab 4
lab 5
4,5
4,5
4,0
4,0
1250 1350 1450 1550 1650
1250 1350 1450 1550 1650
Wavelength [ nm]
Wavelength [ nm]
f) Average ± 2σ of attenuator 9
e) Attenuator 9 – Common reference plugs

Figure 7 – 5 dB attenuators – All lab. results – Common reference
Attenuation [dB] Attenuation [dB] Attenuation [dB]
Attenuation [dB] Attenuation [dB] Attenuation [dB]

TR 62627-02 © IEC:2010(E) – 23 –
Attenuator 10 - common reference plugs
± 2σ
Attenuator 10 - average
6,0
6,0
5,5
5,5
lab 1
lab 2
lab 3
5,0
5,0
lab 4
lab 5
4,5
4,5
4,0
4,0 1250 1350 1450 1550 1650
1250 1350 1450 1550 1650
Wavelength [ nm]
Wavelength [nm]
h) Average ± 2σ of attenuator 10
g) Attenuator 10 – Common reference plugs
Attenuator 11 - common reference plugs
Attenuator 11 - average ± 2σ
6,0
6,0
5,5
5,5
lab 1
lab 2
lab 3
5,0
5,0
lab 4
lab 5
4,5
4,5
4,0
4,0 1250 1350 1450 1550 1650
1250 1350 1450 1550 1650
Wavelength [nm]
Wavelength [nm]
j) Average ± 2σ of attenuator 11
i) Attenuator 11 – Common reference plugs
Attenuator 12 - common reference plugs
Attenuator 12 - average ± 2σ
6,0
6,0
5,5
5,5
lab 1
lab 2
lab 3
5,0
5,0
lab 4
lab 5
4,5
4,5
4,0
4,0
1250 1350 1450 1550 1650
1250 1350 1450 1550 1650
Wavelength [nm]
Wavelength [nm]
l) Average ± 2σ of attenuator 12
k) Attenuator 12 – Common reference plugs

Figure 7 – 5 dB attenuators – All lab. results – Common reference (continued)
Attenuation [d
...