THORLABS INTUN TL 1550-T User manual

TL-T
INTUN Tunable Laser
Manual

INTUN Tunable Laser
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Table of Contents
Part 1. Handling the INTUN TL-T.............................................................................................................. 4
1.1. Safety Requirements......................................................................................................................................4
1.2. ESD Precautions.............................................................................................................................................4
Part 2. Introduction....................................................................................................................................... 5
2.1. Features and Options.....................................................................................................................................5
Acronyms and Abbreviations............................................................................................................................................5
Important Messages ..........................................................................................................................................................5
Part 3. System Description and Interfaces................................................................................................... 6
3.1. What is a Tunable Laser Source (TLS)?......................................................................................................6
3.2. Brief System Overview ..................................................................................................................................6
3.3. Basic Operation..............................................................................................................................................7
3.4. Mechanical Interface ...................................................................................................................................10
3.5. Electrical Interfaces.....................................................................................................................................12
Grounding Issues ............................................................................................................................................................14
Part 4. Power Supplies................................................................................................................................ 16
4.1. Triangular Generator TL-F........................................................................................................................18
Connecting the TL-F....................................................................................................................................................... 18
Controlling the INTUN with a TL-F...............................................................................................................................19
4.2. Digital Control and Status Signals..............................................................................................................20
Analog Control Signals...................................................................................................................................................24
Electrical Power and Signal Connectors.........................................................................................................................28
4.3. Optical Interface...........................................................................................................................................30
Part 5. Operation......................................................................................................................................... 31
5.1. Switching ON the INTUN TL-T .................................................................................................................31
5.2. Switching OFF the INTUN TL-T ...............................................................................................................32
5.3. Calibration of the INTUN TL-T.................................................................................................................32
Part 6. Maintenance and Service................................................................................................................ 35
6.1. Transporting, Storage, Packaging, and Unpacking..................................................................................35
6.2. Cleaning ........................................................................................................................................................35
Part 7. Troubleshooting and FAQ.............................................................................................................. 36
Part 8. Technical Specifications................................................................................................................. 37
Part 9. Regulatory ....................................................................................................................................... 38
Part 10. Thorlabs, Inc. Worldwide Contacts................................................................................................ 39

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Table of Figures
Figure 1: The ESD wrist strap is connected to ground to minimize ESD failure. ................................ 4
Figure 2: Schematic of the INTUN TL-T.............................................................................................. 6
Figure 3: The INTUN TL780-T case .................................................................................................... 9
Figure 4: Front view of the INTUN TL780-T..................................................................................... 10
Figure 5: Side views of the INTUN TL-T........................................................................................... 10
Figure 6: The physical layout of the INTUN TL780-T....................................................................... 11
Figure 7: The INTUN TL780-T control and monitor controls and status signals............................... 13
Figure 8: Power (upper) and signal (lower) connectors ...................................................................... 13
Figure 9: INTUN TL-T recommended connections for electrical power and analog signals............. 15
Figure 10: TL-F control box for the INTUN TLX-T laser.................................................................... 16
Figure 11: Connecting the TL-F with the INTUN ................................................................................ 18
Figure 12: TL-F to INTUN Connection Cables .................................................................................... 19
Figure 13: Control knobs for the TL-F Control Box............................................................................. 20
Figure 14: Digital Input Circuitry.......................................................................................................... 21
Figure 15: Digital output circuitry......................................................................................................... 22
Figure 16: Analog input circuitry.......................................................................................................... 25
Figure 17: Wavelength tuning signal verse laser wavelength ............................................................... 26
Figure 18: Output powers compared to wavelength tuning range. ....................................................... 27
Figure 19: The rear connectors on the INTUN TL-T............................................................................ 28
Figure 20: Typical wavelength deviation as a function of input voltage. ............................................. 33
Figure 21: Illustration of the calibration sequence ................................................................................ 34

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Part 1. Handling the INTUN TL-T
1.1. Safety Requirements
The INTUN TL-T is a sensitive product and should be handled accordingly. To avoid damage to the
INTUN TL-T or personnel handling the laser, the following precautions should be followed:
•Read this manual carefully before powering up the INTUN TL-T or connecting the INTUN TL-
T to any other equipment.
•Do not under any circumstances look into the optical output when the device is operating. The
laser radiation is not visible to the human eye, but it can seriously damage your eyesight.
•Protect the equipment from external shock and excessive vibrations.
•To avoid harmful shock, do not operate the INTUN TL-T if there are any signs of damage to any
part of the outer enclosure (covers, panels, etc.).
•Do not expose the equipment to rapid temperature fluctuations.
•The INTUN TL-T is not designed for outdoor use.
•Do not expose the equipment to dust, dusty air, condensation, or high humidity.
•Always store and use the INTUN TL-T in a vertical position (as further described in the manual).
•Handle with care when unpacking the INTUN TL-T.
•The original transport case supplied by Thorlabs should always be used when shipping the
INTUN TL-T to Thorlabs for service.
•Use an ESD wrist strap when handling the INTUN TL-T.
•Do not use solvents on or near the equipment as they may damage the INTUN TL-T.
•Handle all connectors, both electrical and optical, with care. Do not use unnecessary force as this
may damage the connectors.
•Depending on the model, the laser will be a class 3R or 3B laser product and proper safety
precautions should be taken.
1.2. ESD Precautions
All types of electronic components, particularly integrated circuits, are sensitive to electrostatic
discharge (ESD), a common cause of electronic equipment failure. Equipment failure due to ESD can be
reduced by always wearing an ESD wrist strap whenever handling boards or units.
Figure 1: The ESD wrist strap is connected to ground to minimize ESD failure.

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Part 2. Introduction
This manual describes how to interface and control the INTUN TL-T continuously tunable laser source
(TLS), a flexible OEM module that is designed and manufactured by Thorlabs and is intended for
integration into a variety of fiber optic test and measurement equipment, sensors, and spectroscopy
systems. It can be used in step or sweep mode, and the wavelength and optical power are controlled by a
simple analog interface.
This manual will sometimes refers to other documents (e.g., product specification, packing instructions),
all of which can be obtained from Thorlabs.
2.1. Features and Options
The INTUN Lasers manufactured by Thorlabs combine broad wavelength tunability with quick tuning
speed, linearity in sweep, high absolute accuracy, and repeatability. Some of the main features are
highlighted below:
•High absolute accuracy eliminates the need for frequent calibrations.
•Good repeatability results in consistent measurements.
•Truly continuous, smooth tuning (i.e., small tuning speed variations, no backward movements,
and no mode hops) is important for many applications such as interferometry and fiber sensing.
•The narrow linewidth is a prerequisite for high-resolution interferometric, heterodyne, and
spectroscopic measurements.
•Wide tuning range covers one or two bands, leading to a flexible laser source that eliminates the
need for multiple sources.
•High tuning speed results in fast measurements, saving time and money.
•Compact size and easy-to-integrate interface leads to a cost-effective system that provides
maximum flexibility and rapid implementation.
Acronyms and Abbreviations
The first time an abbreviation appears in the manual, the expanded form is shown, followed by the
abbreviation in parentheses [e.g., Electrostatic Discharge (ESD)]. Thereafter, the abbreviated form is
used.
Important Messages
Red highlighted text is used throughout this manual to alert the user to important messages and warning
messages. Both types of messages are illustrated below. These directions are meant to highlight
information, which if neglected can result in permanent damage to the product, serious injury to the
user, or fatality.
Attention/Warning!
This is an example of an attention or warning message.

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Part 3. System Description and Interfaces
This chapter is intended as an aid for designing a system that contains an INTUN TL-T. In order to
ensure that the INTUN TL-T will operate correctly and meet the stated specifications, requirements
regarding handling and operation stated within this manual must be met.
3.1. What is a Tunable Laser Source (TLS)?
A Tunable Laser Source (TLS) is a laser whose output wavelength can be swept (continuous or random
access) over a certain wavelength range. The INTUN TL-T laser’s tuning range typically varies from 3-
150 nm, depending on the model chosen. The TLS can be thought of as an optical equivalent to the
conventional electrical sweep oscillator. Although the acronym TLS is sometimes used interchangeably
with ECL (External Cavity Laser), ECL actually refers to the technical design of the laser itself.
Therefore, TLS encompasses a larger number of products than ECL since an ECL is not necessarily
tunable.
TLS’s are frequently used in various measurement applications to record some quantity (e.g., intensity)
as a function of wavelength. Each application requires detailed knowledge of some or all of the
parameters that characterize a TLS (e.g., wavelength range, side mode levels, spontaneous noise levels,
line width, sweep characteristics).
3.2. Brief System Overview
As shown in Figure 2, the INTUN TL-T is a TLS based on a semiconductor laser mounted in a Littrow
external cavity laser geometry. This tuning arrangement allows for high output power while maintaining
a large mode-hop-free tuning range.
1
234
5
6
Figure 2: Schematic of the INTUN TL-T
The INTUN is based on a Littrow resonator: 1) diffraction grating, 2) intra-cavity collimating hybrid
(i.e., refractive and diffractive combination) achromatic lens, 3) laser diode, 4) output coupling optics
including an isolator, 5) optical fiber, and 6) motor.

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The interface between the INTUN TL-T and the user is analog. Analog voltages are used to set the
output wavelength and output optical power; however, a stable voltage source is necessary for supplying
these analog control signals. By applying an analog voltage to the interface, the wavelength can be either
tuned randomly to any wavelength or continuously tuned (i.e., swept) between any two wavelengths
within the specified operational wavelength range for that model. The tuning is truly continuous due to
the construction of the tuning arrangement (i.e., no stepper motor drive).
The INTUN TL-T is fully controlled by its electronic control system and the user-supplied analog
signals for setting output wavelength and optical output power. Furthermore, the INTUN TL-T requires
an external DC power supply to be operational.
3.3. Basic Operation
The INTUN TL-T is based on a patented, low source, spontaneous emission (SSE), Littrow-style
external cavity laser geometry. The intra-cavity lens collimates the light emitted from the laser diode
before the beam impinges on the diffraction grating. Wavelength selectivity is achieved by tilting the
diffraction grating. The amount of tilt is controlled by a patented moving coil (“motor”) arrangement
and is chosen such that the reflected beam is directed back towards the laser diode. Thus, the laser
resonator cavity is formed between the diffraction grating and the left-hand side of the laser diode as
shown in Figure 2 above. The output beam is collimated and sent through an optical isolator before the
beam is launched into the optical fiber.
Due to the analog interface, the INTUN TL-T is easy to integrate into any system configuration. The
user supplies an analog signal to tune (sweep) the laser between the minimum and maximum
wavelengths defining the tuning range. The tuning of the INTUN TL-T is truly continuous. The output
wavelength of the laser will follow the applied analog signal. Furthermore, by applying a constant
voltage to the tuning input, the laser will lase at a fixed wavelength. Therefore, the laser can randomly
access any fixed wavelength within its tuning range.
The control system continuously monitors the angular position and the angular speed of the mechanical
arm onto which the grating is mounted. The outputs are fed to the internal control circuitry. The
wavelength control system is designed to do the following:
•Follow a ramp (i.e., wavelength vs. time signal) without errors and with short settling times.
•Keep the laser at a fixed wavelength (i.e., a fixed angular position of the grating arm) without
errors.
•Obtain fast step response with short settling times when moving between fixed wavelengths
(“random access” tuning).
•Minimize errors in position due to external forces such as vibrations or magnetic fields.
The control system also monitors the optical output power, which can be set by the user using an analog
control port; once set, the system will maintain that input power over the entire tuning-range of the
INTUN TL-T.
The laser chip and the laser cavity are kept at a constant temperature using a closed-loop thermoelectric
cooler.

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The inner metal casing functions as a body for the attachment of the different modules, such as fiber
coupling, laser unit, and sensor mechanics. The outer casing is made of metal and a layer of thermal
isolating material. In addition, a magnetic shield, constructed from a high permeability material,
prevents external magnetic fields from interfering with the motor coils.
All lasers, and especially lasers having resonator cavities defined by mechanical tolerances, are delicate
precision instruments, and they must be handled accordingly. The INTUN TL-T is designed to withstand
normal transport and operating conditions.

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Figure 3: The INTUN TL780-T case

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3.4. Mechanical Interface
Measuring 49 x 93 x 260 mm (W x H x L) (49 x 93 x 274.1 mm if the locking mechanism belonging to
the signal connector is included), the INTUN TL-T provides a powerful laser source in a small footprint.
The front and side views of the INTUN TL-T are shown in Figures 4 and Figure 5, respectively.
Figure 4: Front view of the INTUN TL780-T.
Figure 5: Side views of the INTUN TL-T.
Mounting the INTUN TL-T
The orientation of INTUN TL-T must be horizontal during operation. There are two mounting slots (M6
or 1/4") on the front of the INTUN TL-T as shown in Figure 4. The laser should be secured using both
mounting slots.

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Figure 6: The INTUN with control unit
Environmental Conditions
Warning!
Sudden changes in temperature should be avoided as they may cause condensation to form
on the optical equipment, leading to a negative influence on the device’s performance.
In order to ensure specified performance, the unit is designed to withstand the following ETSI
(European Telecommunications Standards Institute) standards with the exceptions given below.
Storage and Transport
ETS 300 019-1-1.1 (Storage in partially temperature-controlled locations)
ETS 300 019-1-2.2 (Careful transport)

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Applicable EMC standards
EMC testing is done according to EN 61326-1 Annex A “Immunity test requirement for equipment
intended for use in industrial locations”
Emission according to EN 55022 class B
Immunity against radiation according to EN 61000-4-2, 4-3, 4-4, 4-5, 4-6, and 4-8
Immunity against radiation according to ENV 50204
Safety Standards
Safety requirements for electrical equipment for measurement, control, and laboratory use as outlined in
the EN 61010-1 standard
UL 3101-1 standards for electrical equipment for laboratory use
According to IEC 60825-1 edition 1.2 2001-08 (laser safety), the INTUN TL-T is classified as 3B or 3R
depending on model. Refer to the label on the laser itself for classification.
Laser safety classifications as outlined in IEC 825
Exceptions and Extensions to Standards Compliance
Operating temperature range: 15 to 30 °C
Dew point: <26 °C noncondensing environment (RH 85%) @ 30 °C
External vibration will gradually degrade the performance.
External magnetic field at the surface: < 6 µT at 30 – 200 Hz (5 A/m)
3.5. Electrical Interfaces
IMPORTANT!
Read this chapter carefully before connecting the INTUN TL-T to any voltage source.
The INTUN TL-T is fully controlled and monitored by a set of analog and digital control1and status2
signals as shown in Figure 7.
1A control signal is defined as an input signal to the INTUN TL780-T (written to INTUN TL780-T). The control signals can
be either analog or digital.
2A status signal is defined as an output signal from the INTUN TL780-T (read from the INTUN TL780-T).

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Figure 7: The INTUN TL780-T control and monitor controls and status signals.
The user needs to provide the following electrical connections:
•DC power +5 V and ±15 V (see page 14)
•DC voltage, low noise, [ -10 V, 10 V] for setting the output wavelength (see page 25)
•DC voltage, low noise, [ -1 V, 10 V] for setting the optical output power level (see page 26).
•Setting appropriate digital control signals (0 V / 5 V logical levels) (see page 20).
•Reading the status of appropriate digital status signals (0 V / 5 V logical levels) (see page 22).
The electrical signals are accessible via the two connectors located on the rear side of the INTUN TL-T
and shown in Figure 8. The top (6 pin) connector connects the DC power supply to the INTUN TL-T
and the lower (40 pin) connector contains all other electrical control and status signals.
Figure 8: Power (upper) and signal (lower) connectors

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This table lists the signals used to control and monitor the INTUN TL-T.
Signal Type Note
_WAVELENGTH_TUNING Analog Control -10 to 10 V
_FINE_TUNING Analog Control -10 to 10 V
_OPTICAL_POWER Analog Control -1 to 10 V
_FINE_TUNING_ENABLE Digital Control
On = 0 V
Off = +5 V
_OPTICAL_POWER_ENABLE Digital Control
On = 0 V
Off = +5 V
_WAVELENGTH_TUNING_ENABLE Digital Control
On = 0 V
Off = +5 V
_COHERENCE_CONTROL_ENABLE Digital Control
On = 0 V
Off = +5 V
_CONSTANT_CURRENT_ENABLE Digital Control
On = 0 V
Off = +5 V
TBD Digital Status
TRUE = 0 V
FALSE = +5 V
Duration time > 100 µs
_SYSTEM_ERROR Digital Status
TRUE = 0 V
FALSE = +5 V
_TEMPERATURE_ERROR Digital Status
TRUE = 0 V
FALSE = +5 V
Internal temperature
_WAVELENGTH_ERROR Digital Status
TRUE = 0 V
FALSE = +5 V
_OPTICAL_POWER_ ERROR Digital Status TRUE = 0 V
FALSE = +5 V
Grounding Issues
Prior to connecting the INTUN TL-T to any electrical power or signal source, care must be taken to
avoid ground loops. The ground loops may pick up noise and other disturbances from the surrounding
electromagnetic environment. Such disturbances may lead to reduced performance (or malfunctioning)
of the INTUN TL-T.
There are two connectors on the rear side of the INTUN TL-T: one connector for electrical power and
one connector for the control and status signals. Both connectors have pins connected to ground. All
pins labeled GND are physically joined inside the INTUN TL-T.
We recommend that the INTUN TL-T is connected to the (signal) ground via the electrical power
connector; physically join all Row B pins and keep them at 0 V. This connection scheme ensures that
the +5 V, +15 V, and –15 V supplies can be used for the user’s control electronics. However, a ground

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connection between the Row B pins (see page 29) and the ground of the user’s control electronics must
be made.
The three analog control voltages (TUNING_VOLTAGE, OPTICAL_POWER, and FINE_TUNING)
are connected to differential input stages having a high common-mode rejection ratio (CMRR). Hence,
grounding is not recommended for any of the analog control voltage terminals (see Figure 9).
Figure 9: INTUN TL-T recommended connections for electrical power and analog signals

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Part 4. Power Supplies
The TL-F control box, which is shown below, provides all the power and control signals necessary to
run the INTUN TLX-T laser. More details about this all-in-one control box can be found in the next
section.
Figure 10: TL-F control box for the INTUN TLX-T laser.
Alternatively, three user-supplied external power supplies can be used to run the INTUN TL-T unit. If
using this option to power the INTUN laser, the DC Power Supply table below lists the required
voltages; the specifications that these power supplies should meet are outlined in the DC Power Supply
Requirements table. In addition, the pin configuration of the DC power connector can be found on page
29. The full pin configuration of the INTUN TL-T power and signal connectors are shown on page 28.

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DC Power Supply
Voltage Comments
+5 V +5 V supply
GND (+5 V) Return for +5 V connected to the circuit board ground
+15 V +15 V supply
GND (+15 V) Return for +15 V connected to the circuit board ground
-15 V -15 V supply
GND (-15 V) Return for -15 V connected to the circuit board ground
DC Power Supply Requirements
Nominal Voltage Input Voltage Max Voltage Ripple
Max
Operating
Current Comment
+5 V 4.9 to 5.2 V 25 mVpp 2 A
Current surge at power-on
C = 100 nF
+15 V 14.6 to 15.4 V 150 mVpp
(up to 2 MHz) 0.3 A Current surge at power-on
C = 470 µF, Rmin = 0.3 Ω
-15 V -15.4 to -14.6 V 150 mVpp
(up to 2 MHz) 0.3 A Current surge at power-on
C = 470 µF, Rmin = 0.3 Ω
Overall Power Consumption < 20 W
The electrical power is connected to the top (6 pin) connector, which is located on the left side of the
INTUN TL-T.

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4.1. Triangular Generator TL-F
The INTUN TLX-T comes with a TL-F control box, which provides all the power and control signals
needed to run the laser.
Connecting the TL-F
To detach the TL-F from the INTUN, remove the screw at the back (see arrow in the picture below), lift
up, and then out. The TL-F does not need to be attached to the INTUN to work so long as the signal
cable is connected.
Figure 11: Connecting the TL-F with the INTUN
There are three connectors on the back of the TL-F and INTUN as shown above. One cable is connected
to both the INTUN and the TL-F (cream cable), enabling signals to be transferred between the two while
the other is for connecting the power adapter (black cable).

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Figure 12: TL-F to INTUN Connection Cables
Controlling the INTUN with a TL-F
Power On
First, turn on the TL-F, and then turn on the INTUN.
Controls
There are four knobs on the top of the TL-F, each of which allows you to control a different aspect of
the INTUN:
1. Output Power: Sets the output power between its minimum and maximum values. Look in the
test data for maximum output power. To totally extinguish the output power, you need to use the
shutter.
2. Wavelength: Sets the wavelength between its minimum and maximum values or at the center
wavelength for the sweep. See the test data for the wavelength range. Note that 0 corresponds to
the shortest wavelength.
3. Tuning Range: Sets the range you want to sweep; 0 holds the unit at one wavelength and 10
corresponds to sweeping over the entire range. Note: To sweep over the entire range, the
wavelength must be set to 5.
4. Tuning Speed: Sets the tuning speed from approximately 10 nm/s to 100 nm/s (0 ≈10 nm/s and
10 ≈100 nm/s).
Signal Cable1
Power Adapter

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Figure 13: Control knobs for the TL-F Control Box
Constant Wavelength
The TL-F is not made for this type of application and will have a jitter of about ±20 pm or more.
To stand still on a certain wavelength, set the tuning speed to 5 and the tuning range to 0.
4.2. Digital Control and Status Signals
If desired, three user-supplied external power supplies can be used instead of the TL-F control box to
run the INTUN TL-T unit.
Definition of the Logical States
The digital control signals are defined with 0 V (LOW) as ON/TRUE/active/able and with 5 V (HIGH)
as OFF/FALSE/inactive/disable.
Important!
If the input signal is not connected, its default logical state is 5 V (i.e. disabled).
Digital Control Signals
The digital logic control signals are used to enable (or disable) certain INTUN TL-T features. The
control signals could be either TRUE or FALSE. Carefully read through the Digital Control and Status
Signals section starting on page 18 before connecting the INTUN TL-T. The digital input circuitry is
shown in Figure 10.
Definition of the Control Signals
The table below lists the available control signals. Prior to connecting the INTUN TL-T, carefully read
the important note above, which defines the default logical state. The full pin configuration of the
INTUN TL-T power and signal connectors are shown on page 28.