IEC 61280-1-3:2010

IEC 61280-1-3 ®
Edition 2.0 2010-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Fibre optic communication subsystem test procedures –
Part 1-3: General communication subsystems – Central wavelength and
spectral width measurement
Procédures d'essai des sous-systèmes de télécommunication
à fibres optiques –
Partie 1-3: Sous-systèmes généraux de télécommunication – Mesure de la
longueur d'onde centrale et de la largeur spectrale

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IEC 61280-1-3 ®
Edition 2.0 2010-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Fibre optic communication subsystem test procedures –

Part 1-3: General communication subsystems – Central wavelength and

spectral width measurement
Procédures d'essai des sous-systèmes de télécommunication

à fibres optiques –
Partie 1-3: Sous-systèmes généraux de télécommunication – Mesure de la

longueur d'onde centrale et de la largeur spectrale

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX Q
ICS 33.180.01 ISBN 978-2-8322-0931-8

– 2 – 61280-1-3  IEC:2010
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
3.1 Wavelength . 5
3.2 Spectral width . 6
3.3 Additional spectral characteristics . 6
4 Apparatus . 6
4.1 Calibrated optical spectrum analyzer . 6
4.2 Power supplies . 7
4.3 Input signal source or modulator . 7
4.4 Test cord . 7
5 Test sample . 7
6 Procedure (Method A) . 7
6.1 General . 7
6.2 Setup . 7
6.3 Adjustment of spectrum analyzer controls . 8
7 Procedure (Method B) . 8
7.1 Setup . 8
7.2 Adjustment of spectrum analyzer controls . 9
7.3 Continuous LED and SLM spectra . 9
7.4 Discrete MLM spectra . 9
7.5 Continuous SLM spectra . 10
8 Calculation . 10
8.1 General . 10
8.2 Centre wavelength . 10
8.3 Centroidal wavelength . 10
8.4 Peak wavelength . 11
8.5 RMS spectral width (Δλ ) . 11
rms
8.6 n-dB spectral width (Δλ ) . 11
n-dB
8.7 Full-width half-maximum spectral width (Δλ ) . 11
fwhm
8.8 Side-mode suppression ratio (SMSR) . 12
9 Test results . 12
9.1 Required information . 12
9.2 Information to be available on request . 12
10 Example results . 12
Figure 1 – Example of a LED optical spectrum . 13
Figure 2 – Typical spectrum analyzer output for an MLM laser . 15
Figure 3 – Δλ spectral width measurement for MLM laser . 16
fwhm
Figure 4 – Δλ spectral width calculation for MLM laser . 16
fwhm
Figure 5 – Peak emission wavelength and Δλ measurement for SLM laser . 17
30–dB
Table 1 – Measurement points for LED spectrum from Figure 1 . 13
Table 2 – RMS spectral characterization . 14

61280-1-3  IEC:2010 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
FIBRE OPTIC COMMUNICATION
SUBSYSTEM TEST PROCEDURES –
Part 1-3: General communication subsystems –
Central wavelength and spectral width measurement

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
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61280-1-3 has been prepared by subcommittee 86C: Fibre optic
systems and active devices, of IEC technical committee 86.
This second edition cancels and replaces the first edition published in 1998. This edition
constitutes a technical revision with changes reflecting new laser technology and includes a
second method modified for state of the art instrumentation.
This bilingual version (2013-07) corresponds to the monolingual English version, published in
2010-03.
– 4 – 61280-1-3  IEC:2010
The text of this standard is based on the following documents:
CDV Report on voting
86C/ 887/CDV 86C/ 937/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
The French version of this standard has not been voted upon.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 61280 series can be found, under the general title Fibre optic
communication subsystem test procedures, on the IEC website.
The committee has decided that the contents of this amendment and the base 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.
61280-1-3  IEC:2010 – 5 –
FIBRE OPTIC COMMUNICATION
SUBSYSTEM TEST PROCEDURES –
Part 1-3: General communication subsystems –
Central wavelength and spectral width measurement

1 Scope
This part of IEC 61280 provides definitions and measure procedures for several wavelength
and spectral width properties of an optical spectrum associated with a fibre optic
communication subsystem, an optical transmitter, or other light sources used in the operation
or test of communication subsystems.
The measurement is done for the purpose of system construction and/or maintenance. In the
case of communication subsystem signals, the optical transmitter is typically under
modulation.
NOTE Different properties may be appropriate to different spectral types, such as continuous spectra
characteristic of light-emitting diodes (LEDs), and multilongitudinal-mode (MLM), multitransverse-mode (MTM) and
single-longitudinal mode (SLM) spectra, characteristic of laser diodes (LDs).
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 60825-1, Safety of laser products – Part 1: Equipment classification and requirements
IEC 62129, Calibration of optical spectrum analyzers
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 Wavelength
NOTE The following wavelength terms provide quantitative definitions for the describing the central wavelength of
a spectrum. In this standard, “central wavelength” is a general category label for these terms.
3.1.1
centre wavelength
λ
also called “half-power mid-point”, the mean of the closest spaced half-power wavelengths in
an optical spectrum, one above and one below the peak wavelength
3.1.2
half-power wavelength
λ
3dB
a wavelength corresponding to a half peak power value of the optical spectrum

– 6 – 61280-1-3  IEC:2010
3.1.3
peak wavelength
λ
p
the wavelength corresponding to the maximum power value of the optical spectrum
3.1.4
centroidal wavelength
λ
c
the mean or average wavelength of an optical spectrum
3.2 Spectral width
3.2.1
root-mean-square (rms) width
Δλ
rms
the square root of the second moment of the power distribution about the centroidal
wavelength
3.2.2
n-dB-down width
Δλ
n-dB
the positive difference of the closest spaced wavelengths, one above and one below the peak
wavelength λ , at which the spectral power density is n dB down from its peak value
p
3.2.3
full-width at half-maximum
Δλ
fwhm
a special case of n-dB-down width with n = 3
3.3 Additional spectral characteristics
3.3.1
side-mode suppression ratio
SMSR
the ratio of the largest peak of the optical spectrum to the second largest peak, for a
nominally SLM spectrum (see 8.8)
4 Apparatus
4.1 Calibrated optical spectrum analyzer
This special-purpose test equipment uses a dispersive spectrophotometric method to resolve
and record the optical spectral distribution. The required wavelength resolution and range
depends on the type and variety of signals to be measured. Generally, LED sources have
wide spectra with little structure so a range of at least 200 nm and resolution of 1 nm or
narrower are recommended. Laser sources have much narrower spectra and may be used in
wavelength-domain multiplexing (WDM) applications, where more accurate determination of
the wavelength is required. A wavelength resolution of 0,1 nm or narrower is recommended
and the actual requirement is determined by the application. In any case, the sensitivity and
wavelength range of the spectrum analyzer shall be sufficient to measure all of the spectrum
within at least –20 dB from the peak power. For measurement of SMSR, a larger dynamic
range is typically required.
OSA equipment shall be calibrated in accordance with IEC 62129. The equipment used shall
have a valid calibration certificate in accordance with the applicable quality system for the
period over which the testing is done.

61280-1-3  IEC:2010 – 7 –
4.2 Power supplies
As required for the device under test.
4.3 Input signal source or modulator
The input signal source is a signal generator or modulator with the appropriate digital or
analogue signal of the system.
4.4 Test cord
Unless otherwise specified, the physical and optical properties of the test cords shall match to
the cable plant with which the equipment is intended to operate. The cords shall be 2 m to
5 m long, and shall contain fibres with coatings which remove cladding light. Appropriate
connectors shall be used. Single-mode cords shall be deployed with two 90 mm diameter
loops or otherwise assure rejection of cladding modes. If the equipment is intended for
multimode operation and the intended cable plant is unknown, the fibre size shall be
50/125 µm.
5 Test sample
The test sample shall be a specified fibre optic subsystem, transmitter, or light source. The
system inputs and outputs shall be those normally seen by the user. The spectral width
parameters are typically used for characterizing MLM and LED transmitters. The width of
MTM and SLM lasers without modulation are normally too narrow to measure with the
dispersive spectral instruments used with this method. Modulated SLM transmitters have
broadened linewidths for high data rates (above about 2,5 Gb/s) and due to chirp that may be
measurable by this method.
WARNING – Exercise care to avoid possible eye damage from looking into the end of an
energized fibre from any light source. Most importantly, avoid looking into any energized fibre
using any type of magnification device.
The requirements in IEC 60825-1 shall be followed.
6 Procedure (Method A)
6.1 General
Method A is designed for the use of typical commercial optical spectrum analyzer instruments
that allow quick measurement of spectra with 1 000 wavelength samples or more, and allows
for the analysis of such spectra based on all of the samples rather than selecting for example
only the samples at the peaks of mode wavelengths. The previous method using a smaller
number of discrete wavelength points is included in Clause 7 as Method B, for compatibility
with the first edition of this standard. Method A has the advantage of easier simpler
automated analysis and better representation of complex but narrow spectra, such as
multitransverse-mode vertical cavity surface emitting lasers (VCSELs). Due to its convenience
and prevalence in the industry, Method A is considered the reference test method.
6.2 Setup
6.2.1 Use appropriate handling procedures to prevent damage from electrostatic discharge
(ESD), which can cause opto-electronic devices to fail.
6.2.2 With the exception of ambient temperature, standard ambient conditions shall be used,
unless otherwise specified. The ambient or reference point temperature shall be 23 °C ± 2 °C,
unless otherwise specified.
– 8 – 61280-1-3  IEC:2010
6.2.3 Unless otherwise specified, apply a modulated input signal to the optical source. Allow
sufficient time (per manufacturer’s recommendation or as specified in the detail specification)
for the optical source/transmitter to reach a steady-state temperature.
6.2.4 Turn the optical spectrum analyzer on, and allow the recommended warm-up and
settling time to achieve rated measurement performance level.
6.2.5 Connect the optical output of the optical source under test to the optical input
connector of the optical spectrum analyzer. If the transmitter under test does not include
isolation from back-reflections, as often the case at 850 nm, these reflections can cause the
spectrum to be unstable and should be reduced with high return-loss connections and
possibly external isolation or attenuation at the transmitter output.
6.3 Adjustment of spectrum analyzer controls
6.3.1 Using the resolution control, select an appropriate resolution (see 4.1). Typically less
than 1/10 of the spectral width to be measured, or the finest available resolution bandwidth
(0,1 nm or narrower) should be used. Set the number of data points in the acquired signal to
be sure to adequately sample the detail of the optical spectrum. Typically, this is set to at
least 4 times the sample resolution times the total measured width. For example, a 10 nm
measurement span, using 0,1 nm resolution, requires a minimum of 400 points in the
measurement (4 × (total span)/resolution).
6.3.2 Using the span control, select an appropriate span of wavelength range on the display
section of the spectrum analyzer. Initially select a sufficiently wide span to determine the
appropriate position of the peak wavelength; then reduce and adjust the span again to fit all of
the source spectrum or at least all that is within at least 20 dB of the peak power. For SLM
lasers, the span may need to be changed, typically from 2 nm to 20 nm full scale, to
determine the spectral width and SMSR.
6.3.3 Using the gain or reference level control, select a gain or reference level so that the
amplitude of the peak output extends over the entire screen vertical scale.
6.3.4 If available, use the spectrum analyzer log-scale for amplitude measurement, to
achieve the maximum dynamic range
6.3.5 For OSAs that are not capable of performing the subsequent calculations in Clause 8
internally, download the measured optical spectra data to a computer for further analysis in a
format that contains both the wavelength and amplitude of all points in the measurement.
7 Procedure (Method B)
7.1 Setup
7.1.1 Use appropriate handling procedures to prevent damage from electrostatic discharge
(ESD), which can cause opto-electronic devices to fail.
7.1.2 With the exception of ambient temperature, standard ambient conditions shall be used,
unless otherwise specified. The ambient or reference point temperature shall be 23 °C ± 2 °C,
unless otherwise specified.
7.1.3 Unless otherwise specified, apply a modulated input signal to the optical source. Allow
sufficient time (per manufacturer’s recommendation or as specified in the detail specification)
for the optical source/transmitter to reach a steady-state temperature.
7.1.4 Turn the optical spectrum analyzer on, and allow the recommended warm-up and
settling time to achieve rated measurement performance level.

61280-1-3  IEC:2010 – 9 –
7.1.5 Connect the optical output of the optical source under test to the optical input
connector of the optical spectrum analyzer. If the transmitter under test does not include
isolation from back-reflections, as often the case at 850 nm, these reflections can cause the
spectrum to be unstable and should be reduced with high return-loss connections and
possibly external isolation or attenuation at the transmitter output.
7.2 Adjustment of spectrum analyzer controls
7.2.1 Using the resolution control, select an appropriate resolution (see 4.1).
7.2.2 Using the span control, select an appropriate span of wavelength range on the display
section of the spectrum analyzer. Initially select the maximum span to obtain the appropriate
position of the peak wavelength; then adjust the span again so that, at the selected gain, the
smallest detectable output power level occupies the extreme edges of the screen horizontal
scale. For SLM lasers, the span may need to be changed, typically from 2 nm to 20 nm full
scale, to determine the spectral width and SMSR.
7.2.3 Using the gain or reference level control, select a gain or reference level so that the
amplitude of the peak output extends over the entire screen vertical scale.If available, use the
spectrum analyzer log-scale for amplitude measurement, to achieve the maximum dynamic
range.
7.3 Continuous LED and SLM spectra
7.3.1 General
Refer to Figures 1 and 5 for samples of LED and SLM-LD spectrum analyzer outputs. At the
end of several single measurement sweeps, ensure that the output spectrum is stable (power
variation at any wavelength is ≤10 % or ~0,5 dB between sweeps).
7.3.2 Determine the peak wavelength, λp. (Most optical spectrum analyzers have a peak-
search button that automatically performs this function.)
7.3.3 For LEDs, record the two half-power wavelengths, on both sides of the peak
wavelength, that are 3 dB down from the peak amplitude. Determine the number of points to
record (minimum 11), and the wavelength λ and the amplitude p for each point i in the
i i
displayed spectrum as follows.
7.3.4 On both sides of the peak, find the wavelengths closest to the peak, corresponding to
the two points n dB down from the peak (see example in Figure 1), where n is typically 20.
7.3.5 To find 11 equally spaced points, subtract these two wavelengths and divide the result
by 10. This gives the spacing between points.
7.3.6 Starting with the minimum wavelength as the first point, add the wavelength spacing to
find the next point. Continue until 11 points are found (the 11th point should correspond to the
maximum wavelength from 7.3.4). Record the wavelengths in Table 2, Column 2.
7.3.7 Find the output power (in dBm) corresponding to each wavelength point and record in
Table 2, Column 3.
[0,1P(dBm)+6]
7.3.8 Convert the power in dBm to nanowatts (nW) using P(nW) = 10 and record
in Table 2, Column 4.
7.4 Discrete MLM spectra
7.4.1 At the end of a single measurement sweep, measure and record the wavelength and
the amplitude, for all the modes displayed, in Table 2. The display at the end of the

– 10 – 61280-1-3  IEC:2010
measurement sweep will determine the number of modes and the reference nominal
wavelength for each mode. Refer to Figure 2 for a sample spectrum analyzer output.
7.4.2 Measure and record the wavelength and the amplitude for each mode displayed for
each of the 10 single measurement sweeps. Include modes at least n dB below the peak
mode, where n is typically 20 to 25. For each mode at nominal wavelengths measured and
recorded in 7.4.1, calculate the average of the 10 measured wavelengths and the
corresponding average of the 10 amplitude readings. Record these average values in Table 2.
7.4.3 Compare the readings of 7.4.1 and 7.4.2 for each mode. For any mode, if the difference
in wavelength readings is more than 0,2 nm, or the difference in amplitude readings is more
than 10 %, this indicates mode instability and the calculations may not be accurate.
7.5 Continuous SLM spectra
7.5.1 Measure and record the amplitude (M1) at the peak wavelength and the amplitude (M2)
of the strongest side-mode.
7.5.2 Measure and record the two wavelengths, on both sides of the peak wavelength, that
are n dB down from the peak amplitude, where n is typically 20 or 30.
8 Calculation
8.1 General
Many optical spectrum analyzers calculate some or all of the following parameters internally.
Note that for Method A, there will be N points corresponding to all of the data points taken.
Before beginning calculations, it is recommended that any power data points that are more
than 20 dB (or another chosen and documented range) below the maximum power reading not
be used in the calculations. This will especially prevent the user from overestimating the RMS
spectral width. For Method B, the total number of data points N will be the number of recorded
mode peaks.
8.2 Centre wavelength
8.2.1 Continuous LED spectra
This is the average of the half-power wavelengths determined from the result of 6.3.5 for
Method A or in 7.3.3 for Method B.
8.2.2 Discrete MLM spectra
This is the average of the half-power wavelengths that can be determined as follows by
interpolation, since the laser may not have modes at these wavelengths.
Connect the tip of each mode to the tips of adjacent modes as shown in Figure 3; draw a
horizontal line 3 dB down from the peak power point. The two or more intersection points of
the horizontal line with the tip-connecting lines define the half-power wavelengths. The
average of the half-power wavelengths that are furthest separated is λ .
8.3 Centroidal wavelength
Using the wavelengths and corresponding linear power (nW) in Table 2 for Method B or the
result of 6.3.5 for Method A, calculate the centroidal wavelength as follows:
N
 
λ =   P λ
c i i
∑
 
P
 0 
i=1
61280-1-3  IEC:2010 – 11 –
where
th
λ is the wavelength of the i point;
i
th
P is the power of the i point; and
i
P is the total power summed for all points:
N
P = P
0 ∑ i
i =1
N is the number of points.
Refer to Table 1 for a calculation example.
8.4 Peak wavelength
8.4.1 Continuous LED and SLM spectra
Use the value measured in 7.3.2 for Method B or the wavelength of the maximum power in the
spectrum of 6.3.5 for Method A as the peak wavelength.
8.4.2 Discrete MLM spectra
The peak wavelength can be obtained directly the wavelength corresponding to maximum
power in the spectrum from 6.3.5 for Method A or from Table 2 (log or linear scale),
representing the average of 10 readings, by reading the wavelength corresponding to the
peak power level for Method B. If the maximum power occurs in more than one mode, take
the average of the wavelength of all modes with the maximum power. Use the average value
as the peak wavelength.
8.5 RMS spectral width (Δλ )
rms
Using the wavelengths and corresponding linear power (nW), in the spectrum from 6.3.5 for
Method A or from Table 2 (single or average values) for Method B, calculate the rms spectral
width as:
N
 
 
Δλ = P (λ − λ )
rms i i c
∑
 P 
i=1
 
Refer to Table 1 for a calculation example. Note that Δλ does not apply to SLM sources. As
rms
mentioned at the beginning of Clause 8, a documented method for limiting the range of the
data points should be used, such as a cutoff of 20 dB from the peak power.
8.6 n-dB spectral width (Δλ )
n-dB
The difference in wavelengths recorded in 7.5.2 for Method B, or which are n dB below the
peak in the spectrum from 6.3.5 from Method A, is Δλ (see Figure 5). This Δλ applies
n-dB n-dB
to SLM lasers, but does not apply to MLM lasers or to LEDs.
8.7 Full-width half-maximum spectral width (Δλ )
fwhm
8.7.1 Continuous LED spectra
The difference of the half-power wavelengths recorded in 7.3.3 from Method B or determined
λ .
from the spectra of 6.3.5 for Method A is Δ
fwhm
– 12 – 61280-1-3  IEC:2010
8.7.2 Discrete MLM spectra
This is the difference of the half-power wavelengths that can be determined as follows by
interpolation, since the laser may not have modes at these wavelengths.
Connect the tip of each mode to the tips of adjacent modes as shown in Figure 3 and draw a
horizontal line 3 dB down from the peak power point. The two or more intersection points
between these lines define the half-power wavelengths. The maximum difference in half-
power wavelengths is Δλ .
fwhm
NOTE The procedure of 8.7.2 uses interpolation based on a segmented linear fit. In many cases, the spectrum
can also be well represented by a Gaussian fit. In this case, the FWHM spectral width can also be calculated on
the basis of the RMS spectral width. For a Gaussian distribution,
.
Δλ = 2,355 × Δλ
fwhm rms
8.8 Side-mode suppression ratio (SMSR)
From the power of the highest signal peak of an SLM, M1, and the power of the highest
sidemode, M2, as determined in 7.5.1 from Method B or from the spectrum of 6.3.5 from
Method A, calculate the ratio (in dB) as:
 M1 
SMSR = 10 log  
M 2
 
9 Test results
9.1 Required information
The required information shall include :
a) Date, title of test, and procedures used
b) Identification of the fibre optic transmitter (terminal device) or the optical source to be
tested, together with applicable data
c) Reference point temperature
d) Results of the examination.
9.2 Information to be available on request
Information to be available on request is as followings:
a) Test equipment used and the latest date of calibration
b) Names of test personnel
c) The measurement uncertainty due to measurement inaccuracy and display resolution
d) Data rate and input signal characteristics, including modulation depth and pulse shape
e) Supply voltage(s) and/or current(s)
f) Bias circuit configuration for discrete optical source
g) Optical output measurement conditions, including details of fibre test cords, pigtail and
standard coupling means, where applicable
h) Optical output measurement conditions, including details of fibre test cords, pigtail and
standard coupling means, where applicable
i) Recommended warm-up time for temperature stabilization.
10 Example results
The output power spectrum (in dBm) of a single-mode fibre coupled, high power, InGaAsP
edge-emitting LED is shown in Figure 1. Columns 1 to 3 in Table 1 show the 11 points

61280-1-3  IEC:2010 – 13 –
selected from the spectrum according to 7.3. Column 4 shows the power converted from
logarithmic to linear units. The products shown in Columns 5 and 6, and the summations
shown in the row labeled “SUM”, are used to calculate the centroidal wavelength λ , and rms
c
spectral width, Δλ , according to 8.3 and 8.5, respectively. The bottom two rows show the
rms
calculated centroidal wavelength and rms spectral width for this LED.
−20
−30
Optical
output
power
−40
(dBm)
−50
1 200 1 300 1 400
Wavelength  (nm)
IEC  1 692/98
Figure 1 – Example of a LED optical spectrum
Table 1 – Measurement points for LED spectrum from Figure 1
Wavelength λ Power (log)
i
i Power (linear) p nW p λ p (λ – λ )
i i i i i c
dBm
m
1 1 226 –44 40 49 040 256 000
2 1 243 –39 126 156 618 500 094
3 1 260 –33 501 631 260 1 060 116
4 1 277 –28 1 585 2 024 045 1 332 985
5 1 294 –24 3 981 5 151 414 573 264
6 1 311 –24 3 981 5 219 091 99 525
7 1 328 –27 1 995 2 649 360 965 580
8 1 345 –31 794 1 067 930 1 207 674
9 1 362 –35 316 430 392 990 976
10 1 379 –39 126 173 754 671 454
11 1 396 –44 40 55 840 324 000
SUM – – 13 485 17 608 744 7 981 668
1 306 –      –
λ
c
24 –      –
Δλ
rms
– 14 – 61280-1-3  IEC:2010
Table 2 – RMS spectral characterization
Wavelength λ Power (log) Power (linear) p 2

i i
i p λ pi (λ – λ )
i i i c
dBm nW
nm
SUM – –
– – – –
λ
c
– – – –
Δλ
rms
The table contains the average wavelength power readings for each point, where i
corresponds to mode number for discrete MLM spectra and to wavelength point for continuous
LED and SLM spectra.
61280-1-3  IEC:2010 – 15 –
Linear scale
Spectrum
500 nW
250 nW
p 2
p 1
1,297 1,302 1,307
λ
λ 5
λ
λ
1 λ
IEC  1 693/98
1 nm/div
Spectrum  dB
Log scale
5 dB / div
−20
p3
p2
p1
−40
1,272 1,292
1,282
λ
λ
λ
IEC  1 694/98
2 nm/div
Figure 2 – Typical spectrum analyzer output for an MLM laser

– 16 – 61280-1-3  IEC:2010
Spectrum  dB
−7
3 dB
2 dB/div
−17
−27
1,305 1,315 1,325
Δλ
fwhm
2 nm/div
IEC  1 695/98
Figure 3 – Δλ spectral width measurement for MLM laser
fwhm
Spectrum  dB
−8
3 dB
2 dB/div
−18
−28
1,305 1,315 1,325
Δλ = λ -λ
fwhm 3 1
λ λ λ
1 2 3
2 nm/div IEC  1 696/98
Figure 4 – Δλ spectral width calculation for MLM laser
fwhm
61280-1-3  IEC:2010 – 17 –
Spectrum  dBm
Peak wavelength and amplitude
-30 dBc
10 dB/div HI.S
Bandwidth (“chirp”)
−40
−29,81
−80
1,5121 1,5131 1,5141 μm
0,2 nm/div
RES 0,1 nm IEC  1 697/98
Figure 5 – Peak emission wavelength and Δλ measurement for SLM laser
30–dB
___________
– 18 – 61280-1-3  CEI:2010
SOMMAIRE
AVANT-PROPOS . 19
1 Domaine d’application . 21
2 Références normatives . 21
3 Termes et définitions . 21
3.1 Longueur d’onde . 21
3.2 Largeur spectrale . 22
3.3 Caractéristiques spectrales supplémentaires . 22
4 Appareillage . 22
4.1 Analyseur de spectre optique (OSA, Optical Spectrum Analyzer) étalonné . 22
4.2 Alimentations électriques. 23
4.3 Source des signaux d'entrée ou modulateur . 23
4.4 Cordon d’essai . 23
5 Echantillon d'essai . 23
6 Procédure (Méthode A) . 23
6.1 Généralités . 23
6.2 Montage . 24
6.3 Réglage des commandes de l'analyseur de spectre optique . 24
7 Procédure (Méthode B) . 25
7.1 Montage . 25
7.2 Réglage des commandes de l'analyseur de spectre optique . 25
7.3 Spectres LED et SLM continus . 25
7.4 Spectres MLM discrets . 26
7.5 Spectres SLM continus . 26
8 Calculs . 27
8.1 Généralités . 27
8.2 Longueur d'onde centrale . 27
8.3 Longueur d'onde centroïdale . 27
8.4 Longueur d'onde de crête . 27
8.5 Largeur spectrale RMS (Δλ ) . 28
rms
8.6 Largeur spectrale n-dB (Δλn-dB) . 28
8.7 Largeur spectrale à mi-hauteur (Δλ ) . 28
fwhm
8.8 Rapport de suppression latérale (SMSR) . 29
9 Résultats . 29
9.1 Informations requises .
...