IEC TR 62627-03-03:2013

Fibre optic interconnecting devices and passive components - Part 03-03: Reliability - Report on high-power reliability for metal-doped optical fibre plug-style optical attenuators

IEC/TR 62627-03-03:2013(E) describes the investigation results of high-power reliability for metal-doped optical fibre plug-style attenuators. This report contains the high-power test results for metal-doped optical fibre SC plug-style optical attenuators, the thermal simulation results and the analysis of degradation modes, long-term reliability test results under high-power conditions and the derivation of maximum limit of optical power for guaranteeing long-term operation. Keywords: high-power reliability for metal-doped optical fibre plug-style attenuators

General Information

• Status: Published
• Publication Date: 06-May-2013
• ICS: 33.180.20 - Fibre optic interconnecting devices
• Technical Committee: SC 86B - Fibre optic interconnecting devices and passive components
• Drafting Committee: WG 7 - TC 86/SC 86B/WG 7
• Current Stage: PPUB - Publication issued
• Start Date: 07-May-2013
• Completion Date: 31-Aug-2013

Overview

IEC TR 62627-03-03:2013 is a technical report from the International Electrotechnical Commission (IEC) that documents the investigation results on high-power reliability for metal-doped optical fibre plug-style attenuators. The report focuses on SC plug-style metal‑doped fibre fixed attenuators (10 dB, 20 dB, 30 dB), presenting high‑power input test results, thermal simulation data, degradation‑mode analysis, long‑term reliability testing and the derivation of maximum optical‑power limits to guarantee safe, long‑term operation.

Key Topics and Technical Findings

• High‑power step stress tests on SC plug‑style attenuators at an ambient temperature of 70 °C revealed failures characterized by a return‑loss decrease of ≥10 dB at input powers in the ~1.4 W to 2.3 W range (samples and test conditions as reported).
• Thermal simulation results indicate internal temperatures can exceed 300 °C at ~2 W input for a 10 dB attenuator, highlighting thermal absorption and local heating as primary drivers of degradation.
• Degradation modes documented include optical‑fibre endface changes such as protrusion or withdrawal of the fibre tip and resulting increases in connector gap, which correlate with degraded return loss.
• Long‑term reliability tests (example: 500 h at 1 W, 70 °C) showed no immediate return‑loss decrease during the test period, but endface deformation (withdrawal/protrusion) was observed post‑test, informing lifetime limit estimates.
• Metrics analyzed: return loss, attenuation variation, fibre endface geometry, stabilization time of return loss, and simulated internal temperature profiles.
• The report derives maximum optical power limits for long‑term operation based on empirical and simulation data.

Practical Applications and Who Uses This Standard

• Component designers and manufacturers use the report to understand failure modes and to design plug‑style attenuators with improved thermal resilience and safety margins.
• Test laboratories and qualification engineers apply the documented test methods (step stress, long‑term exposure) and acceptability criteria when assessing high‑power reliability.
• Systems integrators and network operators (DWDM, Raman/amplified systems) reference the findings to set operational power limits, connector usage policies, and risk mitigation to prevent personal injury, melting, or fire hazards.
• Safety and compliance teams leverage the derived power limits and degradation analyses to inform procurement specifications and installation guidelines.

Related Standards

• Normative reference: IEC/TR 62627-03-02 - Report of high‑power transmission tests of specified passive optical components.
• Use this report alongside relevant IEC fibre‑optic connector and passive component standards when developing test plans, product specifications and safety policies.

Keywords: high‑power reliability for metal‑doped optical fibre plug‑style attenuators, SC plug‑style attenuator, return loss, thermal simulation, long‑term reliability.

Standards Content (Sample)

IEC/TR 62627-03-03 ®
Edition 1.0 2013-05
TECHNICAL
REPORT
colour
inside
Fibre optic interconecting devices and passive components –
Part 03-03: Reliability – Report on high-power reliability for metal-doped optical
fibre plug-style optical attenuators

IEC/TR 62627-03-03:2013(E)
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IEC/TR 62627-03-03 ®
Edition 1.0 2013-05
TECHNICAL
REPORT
colour
inside
Fibre optic interconecting devices and passive components –

Part 03-03: Reliability – Report on high-power reliability for metal-doped optical

fibre plug-style optical attenuators

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
S
ICS 33.180.20 ISBN 978-2-83220-762-8

– 2 – TR 62627-03-03  IEC:2013(E)
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Outline of high-power test for optical attenuators in IEC/TR 62627-03-02 . 7
4 Accuracy of the internal temperature estimated by the thermal simulation . 8
5 Return loss decreasing test for plug-style optical attenuators . 10
5.1 Test samples . 10
5.2 Test set-up and test conditions . 11
5.3 Test results and the analysis . 12
5.3.1 The degradation on high-power condition . 12
5.3.2 The result of permanent fibre withdrawals before and after the test . 13
5.3.3 Stabilization time of return loss decreasing . 15
5.3.4 Relation of optical input power, test temperature and stabilized return
loss . 15
6 Mechanism of fibre withdrawal on high-power condition . 17
6.1 Estimate of the mechanism of fibre withdrawal . 17
6.2 Fibre withdrawal after application of high-power test three times . 18
7 Long-term reliability test . 19
7.1 Test conditions . 19
7.2 Test results . 20
7.2.1 Return loss changing during the test . 20
7.2.2 The performance deviation after the test . 20
7.3 Analysis of long-term, high-power reliability test . 20
8 Conclusion . 20
Bibliography . 22

Figure 1 – Split-sleeve surface temperature measurement system on high-power input
condition for the SC plug style attenuators by Yamaguchi et al. . 8
Figure 2 – Split sleeve out-surface temperature measurement results on high-power
input condition for the SC plug style attenuators by Yamaguchi et al. . 9
Figure 3 – Input-power dependency of split sleeve outer surface temperature of the SC
plug style optical attenuator without housing . 10
Figure 4 – Sample of design – Worst-case endface conditions . 11
Figure 5 – Test set-up of return loss monitor at high-power input into the optical
attenuator . 11
Figure 6 – High-power input test results of optical attenuator . 12
Figure 7 – Result of high-power input test of the optical attenuator . 12
Figure 8 – Relationship between the gap and the return loss . 13
Figure 9 – Distribution diagram of the optical fibre withdrawal of both the optical
attenuator and the optical connector . 14
Figure 10 – Temperature distribution along the central axis derived from thermal
simulation (10 dB optical attenuator) . 14
Figure 11 – Time dependence of the maximum temperature in thermal simulation of the
optical attenuator . 15

TR 62627-03-03  IEC:2013(E) – 3 –
Figure 12 – Return loss decreasing curve in the tests with various test temperatures
and input powers (sample no. ATT44/JC35) . 16
Figure 13 – Relationship between the maximum internal temperature and return loss
stabilization point of the sample tested with various test temperatures and input
powers (sample no. ATT44/JC35) . 16
Figure 14 – Relationship between the maximum internal temperature and the gap at
stabilization of return loss of the sample tested with various test temperature and input
powers (sample no. ATT44/JC35) . 17
Figure 15 – Thermal stress simulation model for three layers of zirconia, epoxy and
silica . 17
Figure 16 – Result of thermal distortion simulation and relationship between the
sample maximum internal temperature and the gap . 18
Figure 17 – Optical fibre withdrawal alternation under repeated power input to the
optical fixed attenuation (70 °C, 1 W, 30 min，repeated inputs) . 19
Figure 18 – High-power, long-term test results of the optical attenuator . 20

Table 1 – Test conditions of optical attenuators . 12
Table 2 – Conditions for high-power, long-term test of the optical attenuator . 19

– 4 – TR 62627-03-03  IEC:2013(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE OPTIC INTERCONECTING DEVICES
AND PASSIVE COMPONENTS –
Part 03-03: Reliability –
Report on high-power reliability for metal-doped
optical fibre plug-style optical attenuators

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
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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 62627-03-03, 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 62627-03-03  IEC:2013(E) – 5 –
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
86B/3458/DTR 86B/3506/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 in 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
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

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 62627-03-03  IEC:2013(E)
INTRODUCTION
Since 2000, the optical power in transmission systems has increased in conjunction with the
increase in the number of channels for DWDM systems, with the help of deployment of
RAMAN amplifiers and application of optical amplifiers. It is pointed out, however, that the
transmission media of the optical transmission system such as the optical fibre, optical
connector and optical passive components may sometimes be hazardous because of possible
leakage of high-power light that results in personal injury, melting, or a damage possibly
causing a fire.
IEC Japan National Committee (JPNC) and Optoelectronics Industry and Technology
Development Association (OITDA) carried out the research on the high-power reliability and
safety of optical passive components. The result was summarized in the OITDA Technical
paper, TP04/SP-PD-2008 “Study on the High-Power Reliability of Optical Passive Parts for
Communications.” IEC/TR 62627-03-02 was published based on the above report. According
to that report, deterioration of optical passive components at high-power input is caused by
temperature rise due to absorption of light as well as consequential thermal distortion. It was
decided to undertake additional research whilst utilizing these findings, specifically on the
plug style optical attenuator, whose resistance against high-power is relatively small. The
study result was summarized in OITDA TP, TP09/SP-PD-2010.
This technical report was prepared on the basis of OITDA TP, TP09/SP-PD-2010,“Technical
paper of investigation of high-power reliability for plug-style fixed optical attenuators”.

TR 62627-03-03  IEC:2013(E) – 7 –
FIBRE OPTIC INTERCONECTING DEVICES
AND PASSIVE COMPONENTS –
Part 03-03: Reliability –
Report on high-power reliability for metal-doped
optical fibre plug-style optical attenuators

1 Scope
IEC/TR 62627-03-03, which is a technical report, describes the investigation results of high-
power reliability for metal-doped optical fibre plug-style attenuators.
This report contains the high-power test results for metal-doped optical fibre SC plug-style
optical attenuators, the thermal simulation results and the analysis of degradation modes,
long-term reliability test results under high-power conditions and the derivation of maximum
limit of optical power for guaranteeing long-term operation.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC/TR 62627-03-02, Fibre optic interconnecting devices and passive components –
Part 03-02: Reliability – Report of high-power transmission test of specified passive optical
components
3 Outline of high-power test for optical attenuators in IEC/TR 62627-03-02
The test was carried out by inputting the high-power light into the SC plug style metal-doped
fibre optical attenuators with an attenuation of 10 dB, 20 dB and 30 dB. The test ambient
temperature was set at the assumed normal maximum operating temperature of 70 °C and the
test method was the step stress test. The test result indicated failures in all the samples, i.e.
the return loss decreased by 10 dB or more at 1,4 W to 2,3 W. Variation of the attenuation
and the return loss before and after the test was within the range of measurement uncertainty.
When the fibre end surface was checked after th test, it indicated either protrusion or
withdrawal of the optical fibre.
On the other hand, thermal simulation was carried out and the result was that the maximum
internal temperature reached 300 °C or more at the input power of 2 W for SC plug style
metal-doped fibre optical attenuator of 10 dB attenuation.
In addition, the long-term reliability test of the optical attenuator was carried out for 500 h.
The test conditions were 1 W for the input power and 70 °C for the ambient temperature. As a
result of the test, it was found that the return loss did not decrease during the test, but
withdrawal or protrusion of the optical fibre was found after the test.
Based on the result of the above tests, it was estimated that the mechanism of return loss
decline consists of the softening of adhesive fixing the metal-doped optical fibre and ferrule,
which in turn causes withdrawal of optical fibre and finally results in loss of physical contact
(PC) between the fibre endfaces. Therefore, for the purpose of guaranteeing long-term
reliability with high power, it is necessary to control the internal maximum temperature within

– 8 – TR 62627-03-03  IEC:2013(E)
the range in which the adhesive does not exceed the glass transition temperature. Thermal
simulation results lead to the assumption that the input power of 500 mW is the limit at the
ambient temperature of 50 °C for SC plug style optical metal-doped fibre optical attenuator of
10 dB attenuation.
After studying IEC/TR 62627-03-02, problems were found on the high power reliability for
plug-style attenuators in the following areas:
– accuracy of internal temperature estimated by the thermal simulation;
– consideration of the variation of ferrule endface geometries for attenuators and optical
connector plugs which affect the condition of PC (physical contact) detaching;
– identification of the mechanism of optical fibre withdrawal;
– confirmation of long-term reliability that considers temperature and humidity conditions.
4 Accuracy of the internal temperature estimated by the thermal simulation
In 2002, Yanagi et al. measured increasing temperature at high-power input for the MU plug-
style optical attenuator [1] . Yamaguchi et al. used a similar test set-up when testing the SC
plug style optical attenuator [2]. Figure 1 shows the test set-up of Yamaguchi et al. while
Figure 2 shows their test results. Test samples were SC plug style optical attenuators without
housing. The resistance temperature detector (RTD) was attached on the outer surface of the
split sleeve to monitor the temperature. The ambient temperature was 23 °C. The test was
carried out for the attenuation of 1 dB, 3 dB, 5 dB, 10 dB, 15 dB and 20 dB, respectively.
Figure 2 shows the test result at the attenuation of 5 dB, 10 dB, 15 dB and 20 dB. It appeared
that the temperature rose approximately linearly to the input power of 500 mW at maximum,
then its rate of rise decreased. The temperature at the input power of 500 mW for 10 dB
attenuator was 75 °C and the temperature rise from the ambient temperature of 23 °C was
52 °C.
SSCC f fererrurulle e
SC ferrule
with metal doped fibre
wwiitth mh meettaall do dopeped fd fiibeberr
Temperature
TTememppereraattuurere
measuring point
mmeeaassururiingng po poiintnt
High optical power
HigHighh o opptticicaal pl poowweerr
Split sleeve
SSpplitlit s sleleeevvee
SC ferrule
SSCC f fererrurullee
IEC  927/13
Figure 1 – Split-sleeve surface temperature measurement system on high-power
input condition for the SC plug style attenuators by Yamaguchi et al.
______________
Numbers in square brackets refer to the Bibliography.

TR 62627-03-03  IEC:2013(E) – 9 –
5 dB
10 dB
15 dB
20 dB
0 200 400 600 800 1 000
Input power  (mW)
IEC  928/13
Figure 2 – Split sleeve out-surface temperature measurement results on high-power
input condition for the SC plug style attenuators by Yamaguchi et al.
On the other hand, IEC/TR 62627-03-02 describes the thermal simulation results of the
maximum internal temperature for SC plug style attenuators with and without housing. The
thermal simulation of outer surface temperature of the split sleeve for SC plug-style optical
attenuators without housing was calculated with the same method as that used in
IEC/TR 62627-03-02. The simulation results are shown in Figure 3. For the SC plug style
attenuator of 10 dB attenuation, the relation between the temperature rise ∆T (°C) and the
input power P (mW) can be explained in the following equation:
∆T = 0,1169 × P (1)
As reported in IEC/TR 62627-03-02, the ambient temperature dependency of temperature rise
was small. For SC plug style 10 dB attenuators, the temperature rise on the condition of input
power of 1 000 mW could be calculated as 129,1 °C and 128,3 °C for the ambient
temperature of 25 °C and 70 °C, respectively.
The test results of Yamaguchi et al. indicated that the input power of 500 mW optical powers
into the 10 dB SC plug style attenuators made a temperature rise of 52 °C. According to the
results of thermal simulation shown in Figure 3, the temperature rise is calculated as
0,116 9 × 500 = 58 °C. Accordingly, this thermal simulation could reproduce the
demonstration results by Yamaguchi et
...