THORLABS GSL Series User manual

GSL Series
Gain-Switched Lasers
User Guide

GSL Series Gain-Switched Lasers
Table of Contents
Chapter 1 Introduction ...............................................................................................................1
Chapter 2 Safety Information......................................................................................................2
Chapter 3 Quick Start Guide........................................................................................................4
Chapter 4 Operation...................................................................................................................5
Chapter 5 Specifications .............................................................................................................9
Chapter 6 Mechanical Drawings................................................................................................11
Chapter 7 Maintenance and Troubleshooting............................................................................12
Chapter 8 Declaration of Conformity.........................................................................................13
Chapter 9 Thorlabs Worldwide Contacts ...................................................................................14

GSL Series Gain-Switched Lasers Chapter 1: Introduction
Rev A, July 25, 2023 Page 1
Chapter 1 Introduction
The GSL series of lasers provide picosecond, nanosecond, and continuous wave operation in a compact, fiber-
coupled, turnkey source. Gain-switched pulse generation with repetition rate control up to 200 MHz and
adjustable pulse widths allow for applications including high-speed imaging and fluorescence lifetime
measurements. They also make these lasers ideal seed sources for additional amplification. Single-mode fiber
output through an FC/APC connector allows for integration with a range of fiber-terminated devices.
Series Overview
Model options are summarized in the table below.
Item #
Typical Center
Wavelength
Picosecond
Pulse Width
Nanosecond
Pulse Width
Max Peak Power
(ps Operation)
Typ. Peak Power
(ns Operation)
GSL106A
1064 nm ± 10 nm
<100 ps
2 to 65 ns
>35 mW
25 mW
GSL131A
1310 nm ± 20 nm
<80 ps
2 to 65 ns
>43 mW
37.5 mW
GSL155A
1550 nm ± 20 nm
<80 ps
2 to 65 ns
>37 mW
30 mW
Inputs and Controls
The back panel of each laser provides controls for the pulse width and repetition rate, as well as an SMA connector
for trigger input and output signals. Available internally-generated repetition rates include 1, 10, 100, and
200 MHz.
Figure 1 GSL Series Laser Back Panel
Pulse Width
Control
Key
Switch
Power
Jack
Trigger
Port
Interlock
Jack
Repetition
Rate Control
Status
LED
Rep Rate
Chart

GSL Series Gain-Switched Lasers Chapter 2: Safety Information
Page 2 TTN311232-D02
Chapter 2 Safety Information
All statements regarding safety of operation and technical data in this instruction manual will only apply when the
unit is operated correctly. If equipment is used in a manner not specified by the manufacturer, the protection
provided by the equipment may be impaired. Only with written consent from Thorlabs may changes to single
components be carried out or components not supplied by Thorlabs be used.
Warnings and Cautions
Warning: Laser Radiation
Avoid Exposure –Radiation emitted
from apertures. Do not look into the
laser aperture while the laser is on.
Injury to the eye may result. Laser
should not be turned on unless there
is an optical fiber connected to the laser
output port.
Caution –Use of controls or adjustments
or performance of procedures other than
those specified herein may result in
hazardous radiation exposure.
Caution: ESD Sensitive Component
The components inside this instrument are ESD sensitive. Take all appropriate precautions to
discharge personnel and equipment before making any connections to the unit.
Caution: Components not Water Resistant
This instrument should be kept clear of environments where liquid spills or condensing
moisture are likely. It is not water resistant. To avoid damage to the instrument, do not expose
it to spray, liquids, or solvents.
Caution: Follow Intended Usage Guidelines
Inputs and outputs must only be connected with shielded connection cables.
The safety of any system incorporating the equipment is the responsibility of the assembler of
the system. If equipment is used in a manner not specified by the manufacturer, the protection
provided by the equipment may be impaired. Only with written consent from Thorlabs may
changes to single components be carried out or components not supplied by Thorlabs be used.
There are no user serviceable components inside this device.
GSL106A Laser
 



GSL131A & GSL155A Lasers

GSL Series Gain-Switched Lasers Chapter 2: Safety Information
Rev A, July 25, 2023 Page 3
Precautions
The following statement applies to the products covered in this manual, unless otherwise specified herein. The
statement for other products will appear in the accompanying documentation.
Note: This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant
to Part 15 of the FCC Rules, and meets all requirements of the Canadian Interference Causing Equipment Standard
ICES-003 for digital apparatus. These limits are designed to provide reasonable protection against harmful
interference in an industrial installation. This equipment generates, uses, and can radiate radio frequency energy
and, if not installed and used in accordance with the instructions, may cause harmful interference to radio
communications. However, there is no guarantee that interference will not occur in a particular installation.
Thorlabs is not responsible for any radio television interference caused by modifications of this equipment or the
substitution or attachment of connecting cables and equipment other than those specified by Thorlabs. The
correction of interference caused by such unauthorized modification, substitution or attachment will be the
responsibility of the user. The use of shielded I/O cables is required when connecting this equipment to all optional
peripherals or host devices. Failure to do so may violate FCC and ICES rules.

GSL Series Gain-Switched Lasers Chapter 3: Quick Start Guide
Page 4 TTN311232-D02
Chapter 3 Quick Start Guide
1. Connect the power supply cable to the laser head and then plug the power supply into mains power.
2. Make sure the interlock pin is in place at this time. An external interlock circuit can be added later for
more convenient integration of the interlock safety feature.
3. Connect the patch cable with FC/APC connector to the laser output mating sleeve.
4. Put laser safety goggles on if your situation requires them.
5. Turn the power switch on using the key switch.
6. The multicolored status LED indicator (red/green/amber) will blink until the laser temperature has
stabilized. Initial warm up can take 30 - 60 seconds. The multicolored laser emission LED (red/blue) will
then glow continuously when the laser output is enabled. Note that there is a four second delay between
the time the emission indicator glows solid and laser output is enabled.
Note: For repetition rate setting “A” and “B” there will be no optical output unless the laser is triggered.
Figure 2 GSL Series Laser with Fiber Patch Cable Connected to Output
Emission LED

GSL Series Gain-Switched Lasers Chapter 4: Operation
Rev A, July 25, 2023 Page 5
Chapter 4 Operation
Block Diagram
The block diagram in Figure 3 depicts the internal architecture of the laser head, which contains all of the pulsing
drive electronics, safety interlocks, trigger circuits, and the temperature stabilization system. The multicolored
LED indicators are designed to be visible through most laser safety glasses. The Status LED blinks during the 30 -
60 s warm up and then turns off once temperature stability is achieved. Additional Status LED indications are
summarized in section 4.6. The Emission LED is active four seconds before laser emission and stays active in any
state where laser emission is possible.
In addition to external triggering with both high impedance (Hi-Z) and 50 Ω termination there are also four
different internally generated repetition rates: 1, 10, 100, and 200 MHz.
Figure 3 Block Diagram of the GSL Series Laser Head
Power
Power is supplied by the external, +15 V, wall-mounted DS15 Power Supply included with the unit and shown in
the left image of Figure 4. The power supply includes a region-specific plug. The mini-XLR type connector, which
uses a latching mechanism to prevent accidental pull-out, plugs into the laser head as shown in the right image of
Figure 4.
Figure 4 The DS15 Power Supply (left) connects to the back panel of the laser head (right).

GSL Series Gain-Switched Lasers Chapter 4: Operation
Page 6 TTN311232-D02
The key switch controls power to all internal components. When the key switch is turned on, the temperature
stabilization system is activated. There is a 30 - 60 second warm up, during which time the LED indicator light
blinks. When the LED stops blinking, there is an additional four second delay and then laser is enabled. Note there
will not be any optical output until the interlock is satisfied, a trigger signal is supplied, and the pulse width and
repetition rate combination are in an allowed state as show in the table in section 4.7.
Interlock Circuit
The laser is equipped with a phono-type interlock jack located on the back panel. To enable the laser source, a
short circuit must be applied across the terminals of the interlock connector. The shorting device (interlock pin)
installed in all units shipped from Thorlabs performs this function. Leave the shorting device installed unless using
an external safety circuit or other type of remotely controlled switch to enable laser output.
Making use of the Interlock feature requires the appropriate 2.5 mm phono-type plug, which is shown in the left
diagram of Figure 5 and is readily available through most electronics retailers. The plug should be wired to the
external safety circuit or switch and then plugged into the back panel’s interlock jack in place of the shorting
device. The electrical specifications of the interlock jack are listed in the following table, and the circuit schematic
describing how the interlock jack is connected inside the laser head is shown in the right diagram of Figure 5.
Parameter
Specification
Interlock Switch Requirements
Must be Normally Open Dry Contacts,
Apply no External Voltages to the Interlock Input
Type of Mating Connector
2.5 mm Mono Phono Jack
Open Circuit Voltage
5 VDC
(Center Pin is at 5 VDC, Ring is Ground)
The user’s safety circuit must be attached to the phono plug and wired such that the ring and center pin are
shorted when it is safe to enable the laser. The laser will be enabled when connection is closed. If it changes to an
open state, the laser source will turn off.
Figure 5 The interlock circuitry internal to the laser head (right) applies a 5 VDC bias across the ring and
center pin of the phono-type plug (left). An external circuit that shorts the ring and center pin enables
the laser.

GSL Series Gain-Switched Lasers Chapter 4: Operation
Rev A, July 25, 2023 Page 7
Repetition Rates and Pulse Widths
The GSL series of lasers has four internally triggered repetition rates and two externally triggered settings
accommodating both Hi-Z and 50 Ωimpedance. The internally available rates include: 1, 10, 100 and 200 MHz.
Use the included 2.5 mm flathead screwdriver to operate these controls.
All of the GSL series offers controls for varying the pulse width. Use the included 2.5 mm flathead screwdriver to
operate this control also, as shown in Figure 7. The range of pulse widths for each model are listed in the
specifications table in Section 5.1. The pulse width control directly programs the pulse generator and has 16
positions, which allows the pulse width to be adjusted to the settings shown in the table in section 4.5. Plots of
typical pulses and of typical pulse width as a function of control setting are available in the web presentation.
Figure 6 Pulse width and repetition rate controls are adjusted with the included 2.5 mm flathead
screwdriver.

GSL Series Gain-Switched Lasers Chapter 4: Operation
Page 8 TTN311232-D02
Trigger Port
The Trigger In/Out port has dual function. If the internal oscillators are used, then the Trigger port provides an
output signal that is synchronized with the pulse generation. Both a Hi-Z and 50 Ωuser-trigger mode are available
for low-frequency and high-frequency operation respectively. In the user-triggered mode, the SMA port allows
external trigger signals to drive the pulse generator. See the Specifications table in 5.2 for the correct signal levels
and impedances. Allowable repetition rate ranges for each pulse duration are given in the table below.
Pulse Width Position
Pulse Width
Max Rep. Rate
Min Rep. Rate
1 MIN
<100 psa
200 MHz
200 kHz
2
2 ns
200 MHz
200 kHz
3
4 ns
100 MHz
200 kHz
4
6 ns
30 MHz
Single Shot
5
8 ns
30 MHz
Single Shot
6
10 ns
30 MHz
Single Shot
7
12 ns
30 MHz
Single Shot
8
14 ns
30 MHz
Single Shot
9
16 ns
30 MHz
Single Shot
10
18 ns
25 MHz
Single Shot
11
20 ns
20 MHz
Single Shot
12
25 ns
16 MHz
Single Shot
13
30 ns
13 MHz
Single Shot
14
40 ns
10 MHz
Single Shot
15 MAX
65 ns
5 MHz
Single Shot
16 CW
CW
N/A
N/A
Status LED
The operational state of the GSL series of lasers is indicated through the multicolor (Red/Green/Amber) “STATUS”
LED on the back panel of the laser. Following typical thermal stabilization and laser emission delay, this LED should
be OFF (-). A full list of the states is summarized in the following table.
Laser State
Status LED State
Red
Green
Amber
Laser Emission
-
-
-
Error
Blinking b
-
-
Interlock OPEN
On
-
-
Rep. Rate Out of Range
-
-
Slow Blinking
Laser Powering On
-
Slow Blinking
-
a
Refer to Section 5.1Chapter 5 for specific values.
b
See Troubleshooting section 7.2 for instructions if an error occurs.

GSL Series Gain-Switched Lasers Chapter 5: Specifications
Rev A, July 25, 2023 Page 9
Chapter 5 Specifications
Optical Specifications
Item #
GSL106A
GSL131A
GSL155A
Center Wavelength
1064 ± 10 nm
1310 ± 20 nm
1550 ± 20 nm
Fiber Typea
HI1060
SMF-28 Ultra
SMF-28 Ultra
Laser Class
3B
1M
1M
Picosecond Pulse Operation
Average Powerb
>0.7 mW
>0.7 mW
>0.6 mW
Pulse Durationc
<100 ps
<80 ps
<80 ps
Spectral Linewidth
<15 nm
<12 nm
<20 nm
Repetition Rates
200 kHz to 200 MHz
Peak Power (Typ. Max)
>35 mW
>43 mW
>37 mW
Power Stabilityd
<1%
Nanosecond Pulse Operation
Pulse Durationsa
2 –65 ns
Repetition Ratese
See Section 4.5
Peak Power (Typical)
25 mW
37.5 mW
30 mW
CW Operation
Average Power
20 mW
Trigger Specifications
Parameter
Specification
Max Input Frequencyf
200 MHz
Input Voltageg
50 Ω(AC Coupled)h
0.2 –5.0 Vpp
Hi-Z, 5 kΩ(DC Coupled)
VIL
0 - 0.8 V
VIH
2.2 - 5 V
Output Voltage
50 Ω
400 mV
Hi-Z
800 mV
Max Timing Jitteri
12 ps RMS
Delay from External Trigger Input to Optical Outputj
44 ± 4 ns
Delay from Internal Trigger to Optical Outputj
3.4 ± 1.5 ns
a
The fiber output is an FC/APC connector with a narrow 2.0 mm key.
b
Specification is given for operation at 200 MHz.
c
Pulse widths are of fixed duration and adjustable over 15 discrete settings, from the minimum to the maximum specified width.
Refer to the web presentation for plots of typical pulses.
d
Stability is the RMS measurement of average power over an 8-hour period of operation.
e
Table in Section 4.5 summarizes Max. Rep. Rate with pulse width. A 40% duty cycle limits the range of operation for longer pulses.
f
The maximum supported edge transition time is 1 ms.
g
This is set using the Repetition Rate dial on the back panel of the laser.
h
This setting is intended for high frequency operation > 1 MHz; minimum cutoff frequency is 318 Hz.
i
Applies to external and internal triggering.
j
Trigger delay is measured between the Trigger SMA connector and the optical output at the fiber connector.

GSL Series Gain-Switched Lasers Chapter 5: Specifications
Page 10 TTN311232-D02
Power, Environmental, and Physical Specifications
Parameter
Specification
AC Input Frequency Range to DS15 Power Supply
50 - 60 Hz
AC Input Voltage to DS15 Power Supply
100 - 240 V
DC Input Voltage Range to Laser
14.5 - 15.5 V
DC Input Current to Laser
1100 mA Max
Operating Temperature Range
10 to 45 °C
Storage Temperature Range
0 to 60 °C
Humidity Range (RH)
5% to 85%
Mass
0.80 kg
Dimensions (L x W x H)
185.6 mm x 100.0 mm x 39.4 mm
(7.31" x 3.94" x 1.55")

GSL Series Gain-Switched Lasers Chapter 6: Mechanical Drawings
Rev A, July 25, 2023 Page 11
Chapter 6 Mechanical Drawings
Figure 7 Mechanical Drawing of GSL Series Laser

GSL Series Gain-Switched Lasers Chapter 7: Maintenance and Troubleshooting
Page 12 TTN311232-D02
Chapter 7 Maintenance and Troubleshooting
Maintenance
The GSL laser should not require regular maintenance. If necessary, the housing can be cleaned using a soft cloth
moistened with a mild glass cleaner. Do not use acetone, chemical solvents, or harsh cleaning solutions, and do
not spray cleaning solutions directly onto the unit. See Section 7.2 for advice on cleaning the lens.
Aside from the procedure outlined in section 7.3, there are no user serviceable components in GSL series lasers.
If malfunctions occur, please contact Thorlabs’ technical support ([email protected]). Do not disassemble
the unit.
See the troubleshooting guide below for basic help.
Troubleshooting
Problem
Suggested Checks
No Output
Check that power is supplied and connected properly.
Check that key switch is turned on.
Confirm that laser is warmed up (30 - 60 s).
Confirm the interlock circuit is complete.
Check that the indicator LED is glowing continuously.
Check that a trigger signal is being provided for REP RATE position “A” and “B”.
Power is Low
Check to see if the fiber end face is dirty.
If so, see the cleaning instructions in section 7.3.
Status LED
Blinking Amber
Internal or externally provided repetition rate is out of range for pulse width.
Check that the repetition rate falls into the allowable range provided in section 4.5.
Status LED
Blinking Red
Temperature control or communications error.
Check that the unit is being operated within the ambient temperature range.
Contact Tech Support to assist with this error.
Fiber Inspection and Cleaning
Should an issue arise with low output power or a distorted beam out of the laser, please follow these instructions
to inspect and clean the end face of the fiber.
1. Turn off the power to the unit and disconnect the power supply.
2. Using a 1.3 mm hex wrench, remove the mating sleeve at the laser output (Figure 8).
3. Pull out the mating sleeve to give access to the fiber connector. Take care not to pull out more than 10 cm
of fiber to allow for inspection and cleaning with fiber cleaner.
4. Once the endface has been inspected and/or cleaned, replace the mating sleeve and test for performance.
Figure 8 Removal of Fiber Mating Sleeve (Left) and Fiber Connector Pulled Out for Cleaning (Right)

GSL Series Gain-Switched Lasers Chapter 8: Declaration of Conformity
Rev A, July 25, 2023 Page 13
Chapter 8 Declaration of Conformity

GSL Series Gain-Switched Lasers Chapter 9: Thorlabs Worldwide Contacts
Page 14 TTN311232-D02
Chapter 9 Thorlabs Worldwide Contacts
For technical support or sales inquiries, please visit us at www.thorlabs.com/contact for our most up-to-date
contact information.
USA, Canada, and South America
Thorlabs, Inc.
[email protected]m
[email protected]om
UK and Ireland
Thorlabs Ltd.
[email protected]m
[e-mail]
Europe
Thorlabs GmbH
[email protected]om
Scandinavia
Thorlabs Sweden AB
[e-mail]
France
Thorlabs SAS
[email protected]m
Brazil
Thorlabs Vendas de Fotônicos Ltda.
[email protected]om
Japan
Thorlabs Japan, Inc.
[email protected]
China
Thorlabs China
[e-mail]

www.thorlabs.com