THORLABS ERM100 User manual

Extinction Ratio Meter
ERM100
Operation Manual
2018

Copyright © 2018 Thorlabs
Version:
Date:
Item No.:
1.2
10-Jul-2018
M0009-510-309

Foreword
Contents
3
1General Information 4
41.1 Safety
51.2 Ordering Codes and Accessories
51.3 Requirements
51.3.1 Hardware Requirements
51.3.2 Software Requirements
2 Installation 6
62.1 Parts List
62.2 Getting Started
3Operating Instruction 7
73.1 Operating Elements
83.2 Operation and Settings
83.2.1 Main Displays
93.2.2 Menu
93.2.2.1 Averaging
93.2.2.2 Remote State
103.2.2.3 Serial Number
103.2.2.4 Firmware Version
113.2.2.5 Bootloader Version
113.2.3 Remote Mode
113.2.4 Error Messages
123.3 Measurement Procedure
123.4 Measurement Principle
123.5 Coupling of linear polarized light into a main axis of a PM fiber
133.6 Alignment of a Laser Diode to a PM Fiber
143.7 Alignment of a PMF Patchcord
143.8 Aligning the connectors key to a main axis of a PM fiber
153.9 Measurement consideration
4Remote Operation 16
164.1 Installing Software
174.1.1 Install NI Visa 4.2
204.1.2 Install Remote Control Application
224.1.3 Install Instrument Communicator
234.1.4 Install Firmware Upgrade Wizard
264.1.5 Install NI Instrument Drivers
274.2 Connect the ERM100
304.3 Remote Control Application

324.4 Write Your Own Application
5Maintenance and Service 33
335.1 Firmware Upgrade
375.2 Version Information
375.3 Troubleshooting
385.4 Replacing Mains Fuses
6 Appendix 40
406.1 Technical Data
416.2 Instrument Driver Command Reference
416.2.1 Common IEEE488.2 Commands
446.2.2 Measurement Commands
456.2.3 Device Setup Commands
466.2.4 Device Status Commands
476.2.5 General System Commands
486.3 Status Reporting
486.3.1 Status Structure
496.3.2 Register Description
526.4 Certifications and Compliances
536.5 Warranty
546.6 Copyright and Exclusion of Reliability
556.7 Thorlabs 'End of Life' Policy (WEEE)
566.8 List of Acronyms
576.9 Thorlabs Worldwide Contacts

© 2018 Thorlabs
We aim to develop and produce the best solution for your application
in the field of optical measurement technique. To help us to live up to
your expectations and constantly improve our products we need
your ideas and suggestions. Therefore, please let us know about
possible criticism or ideas. We and our international partners are
looking forward to hearing from you.
Thorlabs GmbH
Warning
Sections marked by this symbol explain dangers that might result in
personal injury or death. Always read the associated information
carefully, before performing the indicated procedure.
Please read this advice carefully!
This manual also contains "NOTES" and "HINTS" written in this form.
Attention
Paragraphs preceded by this symbol explain hazards that could
damage the instrument and the connected equipment or may cause
loss of data.
Note
3

© 2018 Thorlabs4
ERM100
1General Information
The ERM100 Benchtop Extinction Ratio Meter is designed to analyze the ER of laser light in a
polarization maintaining fiber for any kind of alignment applications like connectorization of PM
fibers or pigtailing of laser diodes with PM fibers.
The easy to use interface combined with a fast USB device interface open a wide range of ap-
plications in Manufacturing, Quality Control, Quality Assurance, and R&D.
Drivers for LabVIEW and C are available and makes it easy to integrate the instrument in test
and measurement systems
1.1 Safety
Attention
All statements regarding safety of operation and technical data in this instruction manual will
only apply when the unit is operated correctly as it was designed for.
The ER meter ERM100 must not be operated in explosion endangered environments!
Before applying power to your ERM100 system, make sure that the protective conductor of the
3 conductor mains power cord is correctly connected to the protective earth contact of the
socket outlet!
Improper grounding can cause electric shock with damages to your health or even death!
All modules must only be operated with proper shielded connection cables.
Only with written consent from Thorlabs may changes to single components be carried out or
components not supplied by Thorlabs be used.
Do not obstruct the air ventilation slots in housing!
Do not remove covers!
Refer servicing to qualified personal!
This precision device is only serviceable if properly packed into the complete original packaging
including the plastic foam sleeves. If necessary, ask for a replacement package.
Attention
Mobile telephones, cellular phones or other radio transmitters are not to be used within the
range of three meters of this unit since the electromagnetic field intensity may then exceed the
maximum allowed disturbance values according to IEC 61326-1.
This product has been tested and found to comply with the limits according to IEC 61326-1 for
using connection cables shorter than 3 meters (9.8 feet).
Vous pouvez trouver les traductions françaises des paragraphes ayant trait à la sécurité
d'utilisation de ce produit sur le lien suivant:
http://www.thorlabs.com/thorcat/17500/ERM100-CSADocument(Français).pdf
Vous pouvez aussi simplement scanner le code QR

© 2018 Thorlabs
1 General Information
5
1.2 Ordering Codes and Accessories
Ordering code
Short description
ERM100
ERM100 Benchtop Extinction Ratio Meter
Please visit our homepage http://www.thorlabs.com for further information.
1.3 Requirements
1.3.1 Hardware Requirements
CPU: 1 GHz or higher
RAM: 256 MB
Graphic card with at least 32 MB memory
Hard disc with at least 100 MB free storage space
Free USB2.0 port
USB cable according the USB 2.0 specification
1.3.2 Software Requirements
The ERM100 software (CD1.1) is compatible with Windows ® XP (32-bit) SP3 operating sys-
tem. A NI-VISA engine V4.2 or higher must be installed. This NI-VISA engines comes with the
Thorlabs ERM100 installation CD.
In order to operate the ERM100 under
· Windows ® Vista (32-bit, 64-bit
· Windows ® 7 (32-bit, 64-bit)
a NI-VISA version 5.0.3 or higher is required. It can be downloaded also from National Instru-
ments' website www.ni.com.

© 2018 Thorlabs6
ERM100
2 Installation
2.1 Parts List
Inspect the shipping container for damage.
If the shipping container seems to be damaged, keep it until you have inspected the contents
and you have inspected the ERM100 mechanically and electrically.
Verify that you have received the following items within the package:
1. 1 ERM100
2. 1 power cord, connector according to ordering country
3. 2 Replacement mains fuses
4. 1 operation manual
5. 1 CD Rom
6. 1 USB Cable
2.2 Getting Started
Connect the ERM100 to the power outlet.
Turn the unit on by pressing the power switch at the front.
After switching on the unit, the display will show the device version and then jump to the opera-
tion screen.
The ERM100 is immediately ready to use after turning on. The rated accuracy is reached, how-
ever, after a warming-up time of approx. 15 minutes.
The chassis ground can be connected to ground potential via the banana connector jack to the
external optical build-up, if required.

© 2018 Thorlabs
3 Operating Instruction
7
3Operating Instruction
3.1 Operating Elements
Front Panel
Rear Panel

© 2018 Thorlabs8
ERM100
3.2 Operation and Settings
The ERM100 is controlled by five buttons on the front. A LC display on the front panel shows all
measurement data in various display configurations. All necessary settings can be easily done
using the control buttons and will be shown on the display.
There are two display modes. In 'Main Display Mode' the actual measurement data is dis-
played. In 'Menu Mode' addition measurement parameters can be modified and system inform-
ation will be shown. The button 'MENU' is used to toggle between this two modes.
3.2.1 Main Displays
There are three different measurement screens. The 'SET' button is used to toggle between
these displays:
The ER display presents the current ER measurement value in dB as well as the current mis-
alignment angle in degree:
The ERmin display shows the minimum ER in dB since the last ERmin-Monitor reset and the
corresponding misalignment angle in degree:
Pressing the button 'CLR' (Clear) while in 'Main Display Mode' resets the minimum ER mon-
itor and the minimum ER value measured from that moment is displayed in the ERmin display.
The last screen is the power display. It shows the power in dBm and the wavelength in nm:
Setting the Wavelength
Setting the wavelength is necessary to determine the correct power. This set value will impact
only the power value but no other measurement values.
· Press the 'SET' button until the power and wavelength menu is displayed.
· Press 'UP' and 'DOWN' buttons once: The "Set Wavelength" display comes up for about 2
seconds.

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3 Operating Instruction
9
· Press within these 2 sec. 'UP' or 'DOWN' buttons to set the desired wavelength. This mode
will be left automatically 2 sec. after the last key-press and the new wavelength is stored.
3.2.2 Menu
Additional settings but the wavelength can be accessed in the 'Menu Mode'. This mode can be
entered by pressing the 'MENU' button. To return to 'Main Display Mode' press the 'MENU' but-
ton again. The ERM100 being in 'Menu Mode' is indicated by an arrow in the upper right corner
of the display pointing to the 'MENU' button.
To navigate in the 'Menu Mode' use the 'UP' and 'DOWN' buttons. If the value of a menu entry
is editable the word 'Set' is displayed in the lower left corner of the Display. Pressing the 'SET'
button enters the edit mode of the selected menu entry. If a menu point is in edit mode, the
'UP' and 'DOWN' buttons are used to modify the value and the 'SET' button is used to save the
new value. If a menu entry is in edit mode a cursor flashes at the position the value will be ed-
ited.
The following menu functions are accessible:
3.2.2.1 Averaging
The ERM100 gains 10 samples per second. With AVERAGING up to 16 samples can be aver-
aged for the display values. A higher AVERAGING value will result in lower display rate. The
AVERAGING value has no effect on the measurement data transferred by the remote interface.
3.2.2.2 Remote State
This menu entry displays the remote state. The following states are possible:
Local
The ERM100 is operated by the front panel. The 'REMOTE' LED on the ERM100 front is off.
This remote state is not editable.

© 2018 Thorlabs10
ERM100
Remote
The ERM100 is operated by the remote interface. The 'REMOTE' LED on the ERM100 front is
on. The front panel can not change settings but this menu entry can be used to switch back to
local mode.
To switch back to local mode press the 'SET' button to enter the edit mode of the 'REMOTE
STATE' menu entry. Then toggle the menu entry value with the 'UP' or 'DOWN' button from
'REMOTE' to 'Go to Local'. Pressing the 'SET' button again switches the ERM100 to 'LOCAL'
state. The display changes to the local state display and the 'REMOTE' LED goes off.
Remote with Local Lockout
The ERM100 is operated by the remote interface. The 'REMOTE' LED on the ERM100 front is
on. The front panel can not change settings. The 'Go to Local' function of this menu entry is
locked by a remote command. Therefore this remote state is not editable. The front panel can
only regain access by an unlock command over the remote interface or by power on reset of
the ERM100.
3.2.2.3 Serial Number
The serial number of the ERM100. This value is not editable.
3.2.2.4 Firmware Version
The version of the ERM100 firmware. This value is not editable.

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3 Operating Instruction
11
3.2.2.5 Bootloader Version
The version of the ERM100 bootloader. The bootloader software is a special part of the
ERM100 firmware. It is used to transfer a new firmware version to the ERM100. This value is
not editable.
3.2.3 Remote Mode
If the ERM100 is in remote control state by the USB interface this is shown by 'REMOTE' LED
on. In remote state no settings can be changed by the front panel. If you try to change any set-
ting for 3 seconds a remote message display is shown.
If the 'CLR' (Clear) button is pressed within these 3 seconds, the instrument is set to local
mode.
If the ERM100 is in remote control state with local lockout and you try to change any setting for
3 seconds a remote with local lockout message display is shown.
In 'Remote with Local Lockout' mode the 'Go to Local' function is disabled by a remote com-
mand. See also menu entry 'Remote State'.
3.2.4 Error Messages
If there is an error and the 'Main Display Mode' is active an error message will be displayed. If
there occur more than one error the most important error message is shown. The error displays
look like that:

© 2018 Thorlabs12
ERM100
3.3 Measurement Procedure
Depending on the alignment task there exist different measurement setups and measurement
procedures. For example the alignment of a laser diode to a PM fiber pigtail has different re-
quirements than the testing of PM fiber patch cords.
The ERM100 can be used to couple linear polarized light into the slow (or fast) axis of a polari-
zation maintaining (PM) fiber as well as align the connectors key to the slow (or fast) axis of the
PM fiber.
3.4 Measurement Principle
The ERM100 is based on a rotating polarizer. A polarizer transmits only the polarized part of
the light which is parallel to its transmission axis. The transmitted power is not only dependent
on the input polarization but also on the degree of polarization (DOP). A photo diode after the
spinning polarizer detects the power.
If the input light is completely linear polarized and the DOP is 100% the measured photo cur-
rent is sinusoidal with its minimum at zero. If the minimum is not equal to zero it can due to an
elliptical input polarization or due to a DOP less than 100%. There are also more factors which
can influence the measurement data like dark current and noise of the photo diode but let us
assume perfect optical elements for our considerations.
If the input light is circularly polarized with a DOP of 100% a DC photo current would be the res-
ult. A purely unpolarized input light would also generate a DC photo current.
Both properties the ellipticity as well as the DOP will affect the measurement result. This should
be considered when measurements with the ERM100 are performed.
3.5 Coupling of linear polarized light into a main axis of a PM
fiber
If linear polarized light is coupled to one of the main axis (slow or fast) of a PM fiber the linear
polarization will be maintained in the fiber. Light with an elliptical polarization or linear polarized
light which is not parallel to one of the main axis will not preserve its polarization state along the
fiber. The output polarization state is not predictable. It depends on the current conditions like
bends and stress of the fiber.
There are several ways to set up an ER measurement. The light source is one of the key ele-
ments. Using a broadband source like an ASE or SLED will simplify the alignment procedure
compared to a narrow band source like a DFB laser.
Narrow bandwidth light source (DFB laser)
It is not sufficient to measure a single ER value to characterize the quality of an PM fiber align-
ment. The output polarization can be linear with a misaligned linear polarization at the input or
even with a elliptical polarization entered into the input. There are many different output polariz-
ations possible. The worst case has to be found to characterize this fiber.
An easy way to generate the worst case is to stress the fiber by pulling it gently. Stress is in-
duced and the output polarization will be changed. The ERM100 stores the worst case / min-
imum ER value and displays this data in the ERmin screen.
ASE Source
Instead of a laser diode a SLED (super-luminescent diode) or an ASE is used as light source. A
SLED has a 3dB bandwidth of 10nm to >60nm and an ASE source typically more than 100nm.
As larger the bandwidth as better suitable is a broadband source for this ER measurement on
PMF method.
In general the polarization of a broadband source is not known. It is necessary to generate a
linear polarization for the complete spectrum. A fiber bench with a polarizer is convenient to
perform this task. The polarizer can be mounted with its transmission axis vertical orientated to

© 2018 Thorlabs
3 Operating Instruction
13
the base plate. Now the incident light from the SLED or ASE is linear polarized. This light is fed
into the slow axis of the PM fiber if the slow axis is orientated to the connectors key and the key
is vertical aligned.
As long as the linear polarized light of the broadband source travels along the slow (or fast) axis
the polarization is maintained and the ERM100 will show a high Extinction Ratio. Values
between 20dB and 30dB are desired. If the linear polarized light is not coupled into one of the
main axes of the PM fiber the linear polarized light is separated into two parts. One is traveling
along the fast and the other along the slow axis. Both parts will travel with different speeds.
Depending on the birefringence of the fiber, its length and the induced stress for example by
bending or temperature the output polarization is not predictable and can vary over time. Fur-
thermore, the birefringence is wavelength dependent. The output of each certain wavelength of
the spectrum of the broadband source will be different. This leads to a depolarization of the
complete light. In this case the ERM100 will detect a low Extinction ratio.
3.6 Alignment of a Laser Diode to a PM Fiber
The alignment of a laser diode to a PM fiber can be done in the following way:
1. The output of the fiber is entered to the input of the ERM100 and the unit is switched on.
2. Toggle to the ER display by pressing the button 'SET'.
3. Rotate the PM fiber in respect to the laser diode until a maximum ER value is displayed.
Typically values between 20dB and 30dB are desired.
4. Change to the ERmin display and reset the minimum ER value by pressing the button 'CLR'.
5. Gently pull the fiber.
6. The shown ER value in the ERmin display represents the minimum ER value.
7. The coupling efficiency can be increased by a trial and error method. Rotate the fiber only
slightly in respect to the laser diode in one direction and repeat step 4 to 6. If the ERmin value
increases try the same direction again otherwise try the opposite direction.
Note
The ERM100 cannot distinguish between the fast and slow axis of a PM fiber. A preadjustment
to the desired main axis has to be performed to align the DUT to the slow (or fast) axis of the
PM fiber.

© 2018 Thorlabs14
ERM100
3.7 Alignment of a PMF Patchcord
The alignment of a PMF patchcord can be performed also with a narrow bandwidth laser
source. However, there are two disadvantages using such a light source. The first is the manual
handling which is divided into a rotating and a pulling (stress) part. The second and main disad-
vantage is that with this method fibers which have a loose tube are difficult to handle.
Loose tube means that the fiber itself and the buffer (tube) are not fixed to each other over the
entire length. If someone pulls the buffer the fiber inside is not necessarily stressed in the same
way like the buffer.
Therefore, a broadband source like a SLED or ASE is more suitable for this task. The Extinc-
tion Ratio measurement of a PM fiber with a SLED can be done in the following way:
1. The output of the PM fiber is entered to the input of the ERM100 and the ERM100 is
switched on.
2. Connect the SLED to the input of the fiber bench with the polarizer.
3. Connect the input of the PM fiber to the output of the fiber bench.
4. Toggle to the ER display by pressing the button 'SET'.
5. Rotate the input of the PM fiber in respect to the fiber bench until a maximum ER value is
displayed. Typically values between 20dB and 30dB are desired.
6. The shown ER value in the ER display represents the minimum ER value.
3.8 Aligning the connectors key to a main axis of a PM fiber
The alignment of the connectors key can also be done using the ERM100. There are several
ways to perform this alignment depending on the type of connector and the equipment used to
assemble a connector to a fiber.
Assuming the connector is already assembled to fiber and the key can still be moved the align-
ing can be performed as follows:
1. Couple linear polarized light into the main axis which has to be aligned to the connectors
key.
2. Toggle to the ER display by pressing the 'SET' button.
3. Rotate the connector until the displayed misalignment angle shows 0°.
Lock the key in the respect to the connector with adhesive or another adequate method.

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3 Operating Instruction
15
3.9 Measurement consideration
The method based on the rotating polarizer does not only take the polarized light into account
for the determination of the ER but also the unpolarized part. Therefore, even if the light with
linear polarization but with a DOP less than 100% enters the rotating polarizer the calculated
ER value depends strongly on the DOP. The following table shows the measured ER value in
relation to the DOP assuming a ideal linear polarization.
DOP [%]
90.0
98.0
99.0
99.8
99.9
99.94
99.98
99.99
99.998
ER [dB]
12.8
20.0
23.0
30.0
33.0
35.0
40.0
43.0
50.0
If the DOP is a problem for the ER measurement a more complex measurement system like
Thorlabs' Polarization Measurement System PAX57xx is required.

© 2018 Thorlabs16
ERM100
4Remote Operation
The ERM100 optical power meter provides a USB 2.0 Full Speed link that allows to remote
control the instrument by a host computer (USBTMC Interface) or upgrade the instrument firm-
ware (DFU Interface). The connection between PC and ERM100 is accomplished by a USB
cable with a male type ‘A’ connector at the PC side and a type ‘B’ connector on the instrument
side.
USBTMC Interface:
The USB link provides an interface according to the USBTMC specification (Universal Serial
Bus Test and Measurement Class Specification (USBTMC) Revision 1.0 April 14, 2003) and
the USBTMC-USB488 specification (Universal Serial Bus Test and Measurement Class, Sub-
class USB488 Specification (USBTMC-USB488) Revision 1.0 April 14, 2003).
There are two categories of command types:
-Set commands that bring the ERM100 to the desired configuration
-Query commands that get data from the ERM100. These commands are always terminated
by a question mark (?).
These commands are described in chapter 'Command Reference' of this document.
Additionally the ERM100 USB driver comes with a VISA Instrument Driver DLL. Details please
see in section Write Your Own Application
Attention
Prior to connect the ERM100 first time to a PC, please install the software from the delivered
with the ERM100 CD! Otherwise, a proper operation is impossible.
4.1 Installing Software
The delivered with ERM100 CD includes:
· Remote Control Application: an application to display and record data over time
· VISA Instrument Drivers: These are drivers to write your own application.
· Instrument Communicator: Basic communication with the instrument
· Device Firmware Upgrade Wizard: Upload a ERM100 firmware update to the instrument
· Install NI VISA: NI VISA Runtime is mandatory to remotely control the ERM100.
Hereinafter the software installation to a Windows XP operating system is described.
Note

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4 Remote Operation
17
For remote operation the NI-VISA engine is required. Please check, if you have installed a NI-
VISA Runtime on your PC.
Attention
From the delivered CD 1.1 the version 4.2 can be installed. This works on Windows XP® sys-
tems only.
If you want to operate the ERM100 from a Windows Vista® or Windows 7® operating system,
you need to install a NI VISA Runtime, version 5.0.2 or higher. You can download it from Na-
tional Instruments' web site www.ni.com/visa/.
If you have installed already an appropriate NI VISA version, the software installation descrip-
tion continues in section Install Remote Control Application.
4.1.1 Install NI Visa 4.2
The installation is simple - just follow the recommendation as per the screen shots:

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ERM100