EXFO XTM-50 Series User manual

User Guide
XTM-50
Optical Tunable Filter
www.EXFO.com

Copyright Information
ii XTM-50
Copyright Information
Copyright © 2021–2023 EXFO Inc. All rights reserved. No part of this publication may be
reproduced, stored in a retrieval system or transmitted in any form, be it electronically,
mechanically, or by any other means such as photocopying, recording or otherwise,
without the prior written permission of EXFO Inc.(EXFO).
Information provided by EXFO is believed to be accurate and reliable. However, no
responsibility is assumed by EXFO for its use nor for any infringements of patents or other
rights of third parties that may result from its use. No license is granted by implication or
otherwise under any patent rights of EXFO.
EXFO’s Commerce And Government Entities (CAGE) code under the North Atlantic Treaty
Organization (NATO) is 0L8C3.
The information contained in this publication is subject to change without notice.
Trademarks
EXFO’s trademarks have been identified as such. However, the presence or absence of
such identification does not affect the legal status of any trademark.
Units of Measurement
Units of measurement in this publication conform to SI standards and practices.
Patents
The exhaustive list of patents is available at www.EXFO.com/patent.
Version number: 3.0.0.1
Information in this document applies to the XTM-50 version B.

Contents
Optical Tunable Filter iii
Contents
Copyright Information .........................................................................................................................................ii
1 Introducing the XTM-50 ........................................................................................................1
Technical Specifications .......................................................................................................................................1
XTM-50 Overview ................................................................................................................................................3
Conventions .........................................................................................................................................................5
2 Safety Information ................................................................................................................7
3 Getting Started with Your XTM-50 .......................................................................................9
Unpacking and Installing the XTM-50 ..................................................................................................................9
Connecting an Optical Source to the XTM-50 ....................................................................................................10
4 Setting the Wavelength/Frequency and FWHM Values .....................................................11
Adjusting the Central Wavelength .....................................................................................................................11
Adjusting the FWHM .........................................................................................................................................14
Reaching a Position on the Bandwidth or Wavelength Tuning Actuator ............................................................16
5 Maintenance ........................................................................................................................17
Cleaning Optical Connectors ..............................................................................................................................18
Cleaning the Cover of the XTM-50 .....................................................................................................................20
Recycling and Disposal ......................................................................................................................................20
6 Troubleshooting ..................................................................................................................21
Displaying the User Documentation ..................................................................................................................21
Contacting the Technical Support Group ...........................................................................................................21
Transportation ...................................................................................................................................................21
7 Warranty ..............................................................................................................................23
General Information ..........................................................................................................................................23
Gray Market and Gray Market Products .............................................................................................................23
Liability ..............................................................................................................................................................24
Exclusions ..........................................................................................................................................................24
Certification .......................................................................................................................................................24
Service and Repairs ............................................................................................................................................25
EXFO Service Centers Worldwide .......................................................................................................................26

Optical Tunable Filter 1
1 Introducing the XTM-50
The XTM-50 is a reliable optical tunable filter that features wavelength and bandwidth
tuning. The large wavelength range, the narrow FWHM and the flat-top shape ensure a
clean extraction of the optical signal. It is designed for closely-spaced channel selection and
extraction in DWDM applications.
The XTM-50 is based on the use of a reflection diffraction grating mounted in a
Littman-Metcalf configuration.
When an optical signal is detected at the XTM-50 input port, the input wave is directed
towards the output port after passing through the XTM-50 monochromator.
Technical Specifications
The following table lists the technical specifications of the XTM-50 models.
All optical specifications apply at constant temperature.
IMPORTANT
The following technical specifications can change without notice. The information
presented in this section is provided as a reference only. To obtain this product’s
most recent technical specifications, visit the EXFO Web site at www.exfo.com.
Standard Ultrafine O-bandaWide
Optical specifications
Wavelength range 1450–1650 nm 1480–1620 nm 1260–1360 nm 1525–1610 nm
Wavelength resolution 5 pmb5 pmb5 pmb5 pmb
Minimum bandwidth
(FWHM)
50 pm
(6.25 GHz)
32 pm
(4 GHz)
50 pm
(8 GHz)
50 pm
(6.25 GHz)
Maximum bandwidth
(FWHM)
950 pm
(120 GHz)
650 pm
(80 GHz)
900 pm
(160 GHz)
5000 pm
(625 GHz)
Bandwidth resolution 1 pm 1 pm 1 pm 0.3 % of FWHM
typical
Filter edge gradient 500 dB/nm
typicalc
800 dB/nm
typical
500 dB/nm
typicalc
500 dB/nm
typicald
Insertion loss 5 dB (4.5 dB
typical)e,f
5 dB (4.0 dB
typical)f,g
5 dB (4.5 dB
typical)f,h
5 dB (4.5 dB
typical)i,j
Flatness 0.2 dBk0.2 dBl0.3 dBk,m 0.2 dBn
Polarization dependent
loss ±0.2 dBe±0.2 dBg±0.2 dBh±0.2 dBi
Out-of-band
suppression (crosstalk)
40 dB (60 dB
typical)o
40 dB (50 dB
typical)o
40 dB (60 dB
typical)o
40 dB (45 dB
typical)o

Introducing the XTM-50
2XTM-50
Technical Specifications
Interfaces
Optical fiber type SMF or PMF SMF
Connector type FC/PC or FC/APC
Operating conditions
Maximum optical input
power
30 dBm 27 dBm
Temperature range 15° to 35°C, indoor use only
Storage temperature -20°C to 60°C
Maximum relative
humidity
80 % for temperatures up to 31°C decreasing linearly to 50 %
relative humidity at 40°C
Altitude 2000 m (maximum operating)
Size and Weight
Dimensions (W x D x H) 193 mm x 231 mm x 164 mm (7.6 in x 9.1 in x 6.4 in)
Weight 3.5 kg (7.7 lbs)
a Specifications apply for wavelengths not equal to any water absorption line.
b Typical, related to user dexterity.
c From -3 and -40 dB for FWHM <800 pm.
d Between -3 and -40 dB. Typically 550 dB/nm @ FWHM = 50 pm,
450 dB/nm @ FWHM = 1 nm, 225 dB/nm @ FWHM = 5 nm.
e From 1500 to 1600 nm & FWHM >100 pm.
f At lowest FWHM the insertion loss is 7 dB typical.
g From 1500 to 1600 nm & FWHM >60 pm.
h From 1280 to 1340 nm & FWHM >100 pm.
iForFWHM>100pm.
j At lowest FWHM the insertion loss is < 7.0 dB.
k Centered width of FWHM - 150 pm. For 150 pm < FWHM < 650 pm.
l Centered width of FWHM - 100 pm. For 100 pm < FWHM < 500 pm.
m From 1280 to 1340 nm.
n Centered width of FWHM - 150 pm. For 150 pm < FWHM < 2000 pm.
o Measured 1 nm away from the -3 dB points.
Standard Ultrafine O-bandaWide

Introducing the XTM-50
Optical Tunable Filter 3
XTM-50 Overview
XTM-50 Overview
Handle
The handle bar enables you to carry the XTM-50.
Micrometer Actuators
Two high resolution micrometer actuators enable you to perform wavelength and
bandwidth tuning.
The screw located on top of the actuators enable you to lock the actuator at the wanted
setting.
³The bandwidth actuator is composed of two graduated scales:
³On the sleeve: 13 mm stroke with 0.5 mm graduation interval.
³On the thimble (rotary part): 250 μm by turn, with 5 μm graduation interval.
³The wavelength actuator includes coarse and fine position adjustments, with four
graduated scales:
³Coarse adjustment:
On the sleeve: 13 mm stroke with 0.5 mm graduation interval.
On the thimble (rotary part): 0.5 mm by turn, with 0.01 mm graduation interval.
³Fine adjustment:
On the sleeve: 200 μm stroke with 25 μm graduation interval.
On the thimble: 25 μm by turn, with 0.5 μm graduation interval.
For more details on how to adjust wavelength and FWHM, see Setting the
Wavelength/Frequency and FWHM Values on page 11.
Connector’s
drawer
Handle
Drawer screw
Lock
Wavelength actuator:
Fine adjustment
Wavelength actuator:
Coarse adjustment
Bandwidth
actuator
Optical
connectors

Introducing the XTM-50
4XTM-50
XTM-50 Overview
Optical Connectors
The two following optical connectors, protected by a dust cap, are located on the front
panel:
³Input: channel filter input port.
³Output: channel filter output port.
The two optical connectors are mounted on a drawer, which enables you to access the
internal optical connectors for cleaning (see Cleaning Optical Connectors on page 18).
Retractable Leg
The retractable leg enable you to tilt the XTM-50 upward for convenient purpose, so that it
stands on both front legs and the rear feet (see Unpacking and Installing the XTM-50 on
page 9).
Labels and markings
Label Description
Identification of the product.
Indicates serial number, model, options (if any) and date
of manufacture.
Warranty seal.
The XTM-50 cover must not be open, otherwise the
warranty is not valid anymore.
MANUFACTURED / FABRIQUE
OPTIONS
MODEL / MODELE
Made in France
xxxx-xx
XTM-50
xxxxxxxxxxxx
SERIAL NUMBER / NUMERO DE SERIE

Introducing the XTM-50
Optical Tunable Filter 5
Conventions
Conventions
Before using the product described in this guide, you should understand the following
conventions:
WARNING
Indicates a potentially hazardous situation which, if not avoided, could result in
death or serious injury. Do not proceed unless you understand and meet the
required conditions.
CAUTION
Indicates a potentially hazardous situation which, if not avoided, may result in
minor or moderate injury. Do not proceed unless you understand and meet the
required conditions.
CAUTION
Indicates a potentially hazardous situation which, if not avoided, may result in
component damage. Do not proceed unless you understand and meet the required
conditions.
IMPORTANT
Refers to information about this product you should not overlook.

XTM-50 7
2 Safety Information
WARNING
Do not install or terminate fibers while a light source is active. Never look directly
into a live fiber and ensure that your eyes are protected at all times.
WARNING
The use of controls, adjustments and procedures, namely for operation and
maintenance, other than those specified herein may result in hazardous radiation
exposure or impair the protection provided by this unit.
WARNING
If the equipment is used in a manner not specified by the manufacturer, the
protection provided by the equipment may be impaired.
WARNING
Use only accessories designed for your unit and approved by EXFO. For a complete
list of accessories available for your unit, refer to its technical specifications or
contact EXFO.
IMPORTANT
Refer to the documentation provided by the manufacturers of any accessories used
with your EXFO product. It may contain environmental and/or operating conditions
limiting their use.
IMPORTANT
When you see the following symbol on your unit , make sure that you refer
to the instructions provided in your user documentation. Ensure that you
understand and meet the required conditions before using your product.
IMPORTANT
When you see the following symbol on your unit , it indicates that the unit is
equipped with a laser source, or that it can be used with instruments equipped
with a laser source. These instruments include, but are not limited to, modules and
external optical units.
IMPORTANT
Other safety instructions relevant for your product are located throughout this
documentation, depending on the action to perform. Make sure to read them
carefully when they apply to your situation.

Optical Tunable Filter 9
3 Getting Started with Your XTM-50
This section explains how to properly install and connect your XTM-50.
Unpacking and Installing the XTM-50
The XTM-50 is a bench-top instrument designed for indoor use only, and is not dedicated to
wet locations. It is designed for use either in the horizontal or tilted position.
To unpack and install the XTM-50:
1. Open the package with care and remove the protective foam.
2. Pull out the XTM-50 vertically from its packaging.
3. Set the XTM-50 on a flat stable surface free of excessive vibration.
4. Place the XTM-50 in the wanted operating position as illustrated in the following figure:
5. To tilt the XTM-50 upward, deploy the two retractable legs located underneath it.
CAUTION
³Do not expose the XTM-50 to rain or excessive moisture.
³Do not install the XTM-50 near flammable gases or fumes.
IMPORTANT
When unpacking, handle the device with care and do not damage the original
shipping container in case the XTM-50 needs to be returned to EXFO.

Getting Started with Your XTM-50
10 XTM-50
Connecting an Optical Source to the XTM-50
Connecting an Optical Source to the XTM-50
To connect an optical source to the XTM-50:
Remove the protective cap from the IN and OUT connectors and connect the appropriate
jumper corresponding to the connector type mounted on your product, as indicated next to
the connectors (see XTM-50 Overview on page 3).
CAUTION
³Make sure you use the appropriate connector type, corresponding to the one
mounted on your XTM-50 (see Technical Specifications on page 1 for available
models).
³Make sure optical connectors are perfectly clean. It is essential to achieve
optimum system performance (see Cleaning Optical Connectors on page 18).
³To prevent premature failure of the XTM-50 optical connectors due to frequent
connections, always keep a fiber-optic jumper cable connected to the XTM-50
optical port while you use the jumper's free end to connect to other devices.
IMPORTANT
Keep protective caps on optical connectors when not in use.

Optical Tunable Filter 11
4 Setting the Wavelength/Frequency
and FWHM Values
Adjusting the Central Wavelength
The wavelength actuator enables you to adjust the wavelength with coarse and fine
adjustment positions.
³Coarse adjustment:
On the coarse adjustment screw, the scale on the thimble is graduated from 0 to 500.
One complete revolution of the thimble reaches one graduated marking on the sleeve.
³On the sleeve: 13 mm stroke with 0.5 mm graduation interval.
1 scale graduation corresponds to:
XTM-50 Standard: 11 nm (typ.)
XTM-50 Ultrafine: 6.5 nm (typ.)
XTM-50 O-band: 12 nm (typ.)
XTM-50 Wide: 11 nm (typ.)
³On the thimble (rotary part): 0.5 mm by turn, with 0.01 mm graduation interval.
1 scale graduation corresponds to:
XTM-50 Standard: 220 pm (typ.)
XTM-50 Ultrafine: 130 pm (typ.)
XTM-50 O-band: 240 pm (typ.)
XTM-50 Wide: 220 pm (typ.)
IMPORTANT
When using thimbles, account for any backlash in the system: always use the
thimble in the same rotating direction.
Coarse adjustment, thimble scale
Coarse adjustment, sleeve scale
Fine adjustment, sleeve scale
Fine adjustment, thimble scale

Setting the Wavelength/Frequency and FWHM Values
12 XTM-50
Adjusting the Central Wavelength
³Fine adjustment:
On the fine adjustment screw, the scale on the thimble is graduated from 0 to 30. One
complete revolution of the thimble reaches one graduated marking on the sleeve.
³On the sleeve: 200 μm stroke with 25 μm graduation interval.
1 scale graduation corresponds to:
XTM-50 Standard: 550 pm (typ.)
XTM-50 Ultrafine: 325 pm (typ.)
XTM-50 O-band: 600 pm (typ.)
XTM-50 Wide: 550 pm (typ.)
³On the thimble: 25 μm by turn, with 0.5 μm graduation interval.
1 scale graduation corresponds to:
XTM-50 Standard: 11 pm (typ.)
XTM-50 Ultrafine: 6.5 pm (typ.)
XTM-50 O-band: 12 pm (typ.)
XTM-50 Wide: 11 pm (typ.)
IMPORTANT
Modifying the FWHM can slightly alter the central wavelength setting. So you may
need to re-adjust the central wavelength after FWHM change.

Setting the Wavelength/Frequency and FWHM Values
Optical Tunable Filter 13
Adjusting the Central Wavelength
To tune the central wavelength:
1. Move the Wavelength tuning coarse thimble as follows:
³To increase the central wavelength from lower wavelength to higher wavelengths,
turn the thimble clockwise (from high to low values).
³To decrease the central wavelength from higher wavelength to lower wavelengths,
turn the thimble counterclockwise (from low to high values).
2. To finely adjust the central wavelength value, move the Wavelength tuning fine thimble
as follows:
³To increase the central wavelength from lower wavelength to higher wavelengths,
turn the thimble clockwise (from high to low values).
³To decrease the central wavelength from higher wavelength to lower wavelengths,
turn the thimble counterclockwise (from low to high values).
3. Tighten the lock screw (see XTM-50 Overview on page 3) to lock the central
wavelength setting.
4. If you had previously adjusted the FWHM, re-adjust it as it may have been slightly
altered by the central wavelength change.

Setting the Wavelength/Frequency and FWHM Values
14 XTM-50
Adjusting the FWHM
Adjusting the FWHM
The bandwidth actuator is graduated from 0 to 250. Two complete revolution of the thimble
reach one graduated marking on the sleeve.
³On the sleeve: 13 mm stroke with 0.5 mm graduation interval.
1 scale graduation corresponds to:
³XTM-50 Standard: 105 pm (typ.)
³XTM-50 Ultrafine: 68 pm (typ.)
³XTM-50 O-band: 96 pm (typ.)
³XTM-50 Wide: not linear, see the following figure.
³On the thimble (rotary part): 250 μm by turn, with 5 μm graduation interval.
1 scale graduation corresponds to:
³XTM-50 Standard: 0.21 pm (typ.)
³XTM-50 Ultrafine: 0.14 pm (typ.)
³XTM-50 O-band: 0.19 pm (typ.)
³XTM-50 Wide: not linear, see the following figure
IMPORTANT
Modifying the central wavelength can slightly alter the FWHM. So you may need to
re-adjust the FWHM after central wavelength change.
Thimble scale
Sleeve scale
FWHM (pm)
Actuator Graduation (sleeve scale, typical values) - Model: XTM-50 Wide only

Setting the Wavelength/Frequency and FWHM Values
Optical Tunable Filter 15
Adjusting the FWHM
To tune the bandwith:
1. Move the Bandwidth tuning actuator as follows:
³To increase the FWHM, turn the actuator clockwise (from high to low values)
³To decrease the FWHM, turn the actuator counterclockwise (from low to high
values).
2. Tighten the lock screw (see XTM-50 Overview on page 3) to lock the FWHM setting.
3. If you had previously adjusted the central wavelength, re-adjust it as it may have been
slightly altered by the FWHM change.
CAUTION
To avoid damaging your XTM-50, do not turn the bandwidth actuator beyond the 0
graduation marked on the sleeve.

Setting the Wavelength/Frequency and FWHM Values
16 XTM-50
Reaching a Position on the Bandwidth or Wavelength Tuning Actuator
Reaching a Position on the Bandwidth or Wavelength
Tuning Actuator
The Acceptance Test Report delivered with your instrument indicates the actuator position
(in mm) of the central wavelength and FWHM on your XTM-50.
This section explains how to adjust the actuators to reach the wanted position.
Reaching a Position on the Bandwidth Tuning Actuator
The bandwidth actuator is composed of two graduated scales:
³On the sleeve: 13 mm stroke with 0.5 mm graduation interval.
³On the thimble (rotary part): 250 μm by turn, with 5 μm graduation interval.
To reach a graduated position on the actuator, you must add both scale values.
Example:
To reach the value of 7.275 mm, proceed as follows:
1. Align value 0 of the thimble to value 7 of the scale on the sleeve.
2. Make a full counterclockwise revolution of the thimble to add 0.250 mm.
3. Turn the thimble counterclockwise to add 0.005 mm.
Reaching a Position on the Wavelength Tuning Actuator
The wavelength actuator enables coarse and fine adjustments.
³Coarse adjustment:
³On the sleeve: 13 mm stroke with 0.5 mm graduation interval.
³On the thimble (rotary part): 0.5 mm by turn, with 0.01 mm graduation interval.
³Fine adjustment:
³On the sleeve: 200 μm stroke with 25 μm graduation interval.
³On the thimble: 25 μm by turn, with 0.5 μm graduation interval.
To reach a graduated position on the actuator, you must add all four scale values.
Example:
To reach the value of 8.852 mm you can use different combinations; the following
procedure explains the "8.7+0.152" combination:
1. On the fine adjustment screw, align value 0 of the rotary thimble to value 100 of the
sleeve scale.
2. On the coarse screw:
2a. Align value 0 of the thimble to value 8.5 of the sleeve scale.
2b. Turn the thimble counterclockwise to reach value 200, which adds 0.200 mm.
3. On the fine screw:
3a. Align value 0 of the thimble to value 150 of the of the sleeve scale.
3b. Turn the thimble counterclockwise to add 4 graduations on the thimble scale
(which is 0.002 mm).