THORLABS S1 Series User manual

Fiber Coupled Laser Sources
Operating Manual
OFF
ON
POWER
LD PWR ADJ.
ENABLE mW
oC
FIBER DFB LASER SOURCE
LASER APERTURE
TEMP. ADJUST
ON
POWER
OFF
LD PWR ADJ.
mW
LASER
ENABLE ON
FIBER LASER SOURCE
LASER APERTURE
LASER
ON
THORLABS, Inc. Phone: [phone]
435 Route 206N Fax: [phone]
Newton, NJ 07860 USA Serial #:_______________

2298-D11e.DOC REV. E 9/5/03 Page 1 of 12
Table of Contents:
Table of Figures........................................................................................................................1
Description................................................................................................................................2
Specifications ...........................................................................................................................2
Electrical: ..............................................................................................................................2
Optical:..................................................................................................................................2
Thermal:................................................................................................................................2
Setting the AC Line Voltage and Installing Fuses.....................................................................3
OPERATION ............................................................................................................................4
S1 SERIES FABREY-PEROT...............................................................................................4
1) Initial Set-up ..................................................................................................................4
2) Turning ON the Source .................................................................................................5
3) Adjusting the Laser Output Power.................................................................................5
4) Turning the Laser OFF ..................................................................................................5
5) Modulating the Laser Output .........................................................................................5
S3 SERIES DFB MODELS ...................................................................................................6
1) Initial Set-up ..................................................................................................................6
2) Turning ON the Source .................................................................................................6
3) Adjusting the Laser Output Power.................................................................................7
4) Turning the Laser OFF ..................................................................................................7
5) Adjusting the Temperature of the Laser Diode..............................................................7
6) Modulating the DFB Laser Output ...............................................................................7
Making the Safety Interlock Connections..................................................................................8
Maximizing the Stability of the S3 Series DFB Laser Source……………………………………12
Table of Figures
FIGURE 1 - LOCATIONS OF LINE SELECT SWITCH AND FUSE HOLDER 3
FIGURE 2 - FRONT AND REAR PANELS OF FABRY-PEROT LASER SOURCE 4
FIGURE 3 - FRONT PANEL OF DFB LASER SOURCE 6
FIGURE 4 - REMOTE INTERLOCK CONNECTOR 8

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Description
The Thorlabs Fiber Coupled Laser Sources are fiber optic laser sources that provide ease of coupling
and simple control of laser diode driven fiber optics. These laser sources are available in two versions, Fabry-
Perot and Distributed Feed Back (DFB). The Fabry-Perot version comes in five available wavelength choices
from 635nm up to 1550nm. The DFB version comes equipped with a thermo-electric cooler to stabilize the output
wavelength, and a 40dB optical isolator to eliminate frequency jitter due to back-reflections. The DFB is available
in 1310nm and 1550nm wavelengths.
Specifications
Electrical:
AC Input: 115VAC 50-60Hz @ 250mA Max
Switch selectable to 230VAC 50-60Hz @ 160mA (All Models)
Analog Modulation Input: 0 – 5V corresponds to 0mW to Max Power (max power varies per unit)
Bandwidth: 0 – 30kHz Sinewave ONLY – Do not apply TTL or squarewave.
50 ΩInput Impedance
Optical:
S1 Series Fabry-Perot
Item # λFiber Power* Actual λ** Thorlabs Fiber Optic Cable
S1FC635 635nm FS-SN-3224 mW nm P1-3224-FC-2
S1FC675 675nm FS-SN-3224 mW nm P1-3224-FC-2
S1FC780 780nm FS-SN-4224 mW nm P1-4224-FC-2
S1FC1310 1310nm SMF-28 mW nm P1-6324-FC-2 or P1-SMF28-FC-2
S1FC1550 1550nm SMF-28 mW nm P1-7324-FC-2 or P1-SMF28-FC-2
S3 Series DFB
Item # λFiber Power* Actual λ**
S3FC1310 1310nm SMF-28 mW nm
S3FC1550 1550nm SMF-28 mW nm
* Maximum power available at the output connector as determined during unit’s final calibration.
** Actual wavelength of laser diode per manufacturer’s spec. sheet.
Setpoint Resolution: +/- 0.01mW
Display Accuracy (mW): +/- 10% of actual power
Adjustment Range: 0mW to rated output power (units are power limited to specifications of Laser Diodes)
Stability: 15 min: +/-0.05dB, 24 hr: +/-0.1dB (After 1 hr. warm-up at 25°C +/-10°C ambient)
Refer to “Maximizing the Output Stability” for helpful advice on improving the performance of your S3
Series Laser Source.
Thermal:
Stability: .005°C / 1°C change in ambient
Setpoint Accuracy: +/- 0.25°C of actual temperature
Setpoint Resolution: +/-0.1°C
Adjustment Range: 20°C +/- 1°C to 30°C +/- 1°C
Mechanical:
Length: 11.5”
Width: 5.3”
Height: 2.5”

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! IMPORTANT! PLEASE READ CAREFULLY!
Setting the AC Line Voltage and Installing Fuses
Your S1 or S3 Series Laser Source has been shipped from Thorlabs, Inc. configured for 115VAC operation. If
you are planning to operate your unit using a 220 / 230VAC input, or need to replace an open fuse, you must
perform the following procedure:
 Remove any AC Input cords that may be connected to the unit.
 Remove the cover of the unit by removing the two 4-40 Phillips head screws located on the bottom rear of the
unit and sliding the cover off. Refer to Figure 2.
 Locate the AC Line Select Switch and Fuse Holder. They are located near the AC Input Module towards the
back of the unit. Refer to Figure 1.
 Using a flat blade screwdriver turn the Line Select Switch to the appropriate setting to match the AC input
voltage you will be using.
 Remove the cover to the fuse holder. The fuse is installed in the cover. Remove the existing fuse and install
the appropriate fuse for the line voltage you will be using:
For 115VAC operation use 250mA
For 220 / 230VAC operation use 160mA
In all cases use only 5mm x 20mm 250VAC Type T Fuses
 Reinstall the cover and replace the two 4-40 Phillips head screws.
 Remove the small label indicating the previous voltage configuration located on the rear panel, above the AC
input housing. Place the label in the box indicating the new AC input configuration or fill in the appropriate
box using a black permanent marker.
Figure 1 - Locations of Line Select Switch and Fuse Holder
Line Select Switch
Set to either 110V or
220V
Fuse Holder
Fuse is installed in the
cover

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OPERATION
S1 SERIES FABREY-PEROT
ON
POWER
OFF
LD PWR ADJ.
mW
LASER
ENABLE ON
FIBER LASER SOURCE
LASER APERTURE
MANUFACTURED BY
TO LASER NOTICE NO.50, DATED 5/27/01
230VAC / 100mA 50-60HZ
115VAC / 200mA 50-60HZ
COMPLIES WITH 21 CFR 1040.10 AND 1040.11
EXCEPT FOR DEVIATIONS PURSUANT
NEWTON, NJ USA
DATE OF MFG.
MOD IN
INTERLOCK
S.N.
435 ROUTE 206
Figure 2 - Front and Rear Panels of Fabry-Perot Laser Source
1) Initial Set-up
 Determine the AC line voltage the unit will be connected to (either 115VAC or 230VAC) and set
the AC Line Voltage Selector Switch to the appropriate position and install the proper fuse.
(Refer to “Setting the AC Line Voltage and Installing Fuses”)
 Locate the unit on a dry, level working surface.
 Make sure the POWER keyswitch on the front of the unit is in the OFF position (Key perpendicular to
working surface).
 Plug the female end of the AC line cord provided into the AC Input Receptacle on the rear of the unit.
Plug the male end into a properly grounded AC socket.
 Connect a Fiber Optic cable to the LASER APERTURE on the front panel of the unit.
Power Adjust
Pot
Keylock Power
Switch
Key removes
only in OFF
position
Laser Enable
Switch
Laser Aperture
Connect FC
Terminated
Fiber Cable
FC Aperture Cover
Must be installed on
A
perture whenever
cable is removed
3 ½ Digit
Displa
y
Laser Emission
Indicator turns
ON 5 seconds
before laser
Remote
Interlock Input
Modulation Input
0 – 5V Max
50
Ω
A
C Input Housing
Cover Screws (2)
Remove to access
line switch and fuse

2298-D11e.DOC REV. E 9/5/03 Page 5 of 12
2) Turning ON the Source
 Turn the POWER keyswitch clockwise. The unit is ON when the 3 ½ Digit Display lights up.
 Make sure the Interlock Input is short-circuited, refer to “Making the Safety Interlock Connections”.
 Press and release the ENABLE switch to turn ON the laser. Immediately the LASER ON indicator
will light up, after a “safety delay” of approximately 5 seconds the laser output will be available at the
LASER APERTURE.
3) Adjusting the Laser Output Power
 Using the LD PWR ADJ. knob on the front of the unit, adjust the Output Power to the desired setting.
 The power shown on the 3 ½ digit display is the optical output at the LASER APERTURE. The
actual power at the end of your fiber optic cable may be less, depending on the quality of the
connections at the FC to FC adapter.
 Each unit is calibrated internally to limit the maximum operating power of the Laser Diode to a safe
operating area.
4) Turning the Laser OFF
 The Laser output should be turned OFF by pressing and releasing the ENABLE switch.
 When completely powering down an enabled unit first press and release the ENABLE switch then
turn the POWER keyswitch counterclockwise (which will turn OFF the entire unit). Anytime the unit is
turned OFF and then turned back ON, the Laser will be disabled until the ENABLE switch is pressed.
5) Modulating the Laser Output
 The MOD IN input can be used to sinusoidally modulate the laser output, or set the laser output
remotely using a 0 to 5V power source.
 The 5V maximum input corresponds to the maximum calibrated power of the laser source. Each unit
is calibrated to achieve the maximum power output for the particular laser diode used in the internal
fiber-coupling package. Due to variations in the coupling process no two units will have the same
maximum power.
 Connect a signal generator or 0 – 5V power source to the unit using a BNC type connector.
 Set the LD PWR ADJ pot on the front panel to its full counter clockwise setting.
 Press the ENABLE switch to turn on the Laser, wait for the “safety delay” to time out.
 Apply the appropriate signal to the MOD IN input. Signals above approximately 5.5V will be clamped
by internal circuits.
 Adjusting the LD PWR ADJ pot will allow for a DC offset on the modulated output. Adjust the input
signal accordingly to avoid clipping the output waveform, which will occur if the unit is driven to its
current or power limits.
 DO NOT apply TTL or squarewave inputs to the MOD IN input. Due to response delays of the
constant power control loop damage to the integrated fiber coupled laser may occur!

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S3 SERIES DFB MODELS
OFF
ON
POWER
LD PWR ADJ.
ENABLE mW
oC
FIBER DFB LASER SOURCE
LASER APERTURE
TEMP. ADJUST
LASER
ON
Figure 3 - Front Panel of DFB Laser Source
1) Initial Set-up
 Determine the AC line voltage the unit will be connected to (either 115VAC or 230VAC) and set
the AC Line Voltage Selector Switch to the appropriate position and install the proper fuse.
(Refer to “Setting the AC Line Voltage and Installing Fuses”)
 Locate the unit on a dry, level working surface.
 Make sure the POWER keyswitch on the front of the unit is in the OFF position (perpendicular to the
working surface).
 Plug the female end of the AC line cord provided into the AC Input Receptacle on the rear of the unit.
Plug the male end into a properly grounded AC socket.
 Connect a Fiber Optic cable to the LASER APERTURE on the front panel of the unit.
2) Turning ON the Source
 Turn the POWER keyswitch clockwise. The unit is ON when the 3 ½ Digit Display lights up.
 Make sure the Interlock Input is short-circuited; refer to “Making the Safety Interlock Connections”.
 Press and release the ENABLE switch to turn ON the laser. Immediately the LASER ON indicator
will light up, after a “safety delay” of approximately 5 seconds the laser output will be available at the
LASER APERTURE.
 The default display mode is Laser Power (mW), however the thermo-electric cooler is activated at
turn on.
Power Adjust
Pot
Keylock Power
Switch
Key removes
only in OFF
p
osition
Laser Enable
Switch
Laser Emission
Indicator turns
ON 5 seconds
before lase
r
Display Select Switch
toggles display
between LD Power and
Temp set point
FC Aperture Cover
Must be installed on Aperture
whenever cable is removed
Laser Aperture
Connect FC
Terminated
Fiber Cable
3 ½ Digit
Dis
p
la
y

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3) Adjusting the Laser Output Power
 Using the LD PWR ADJ. on the front of the unit, adjust the Output Power to the desired setting.
 The power shown on the 3 ½ digit display is the optical output at the LASER APERTURE. The
actual power at the end of your fiber optic cable may be less, depending on the quality of the
connections at the FC to FC adapter.
 Each unit is calibrated internally to limit the maximum operating power of the Laser Diode to a safe
operating area. Allow a minimum of 5 minutes warm-up time for the unit to stabilize.
 Refer to “Maximizing the Output Stability” for helpful advice on improving the performance of your
laser source.
4) Turning the Laser OFF
 The Laser output can be turned OFF by pressing and releasing the ENABLE switch.
 When completely powering down an enabled unit first press and release the ENABLE switch, then
turn the POWER keyswitch counterclockwise (which will turn OFF the entire unit). Anytime the unit is
turned OFF and then turned back ON, the Laser will be disabled until the ENABLE switch is pressed.
5) Adjusting the Temperature of the Laser Diode
 Pressing the C°/mW switch once will toggle the 3 ½ digit display from Laser Power (mW) to Laser
Temperature (C°).
 The display indicates the temperature Set Point of the thermo-electric cooler system.
 Adjustments to the temperature are made with the TEMP. ADJUST knob on the front of the unit.
Clockwise increases the set point, counter-clockwise decreases it.
 Depending on the magnitude of the change in temperature set point, it will take anywhere from a few
seconds to a few minutes for the system to settle into the new operating temperature.
 Refer to “Maximizing the Output Stability” for helpful advice on improving the performance of your
laser source.
6) Modulating the DFB Laser Output
 The MOD IN input can be used to sinusoidally modulate the laser output, or set the laser output
remotely using a 0 to 5V power source.
 The 5V maximum input corresponds to the maximum calibrated power of the S1 Series Laser
Source, which operates using a constant power drive technique. The S3 Series DFB Laser Sources
operate using a constant current drive technique, which causes the actual output power to be
dependent on the operating temperature as set using the TEMP ADJ pot. That is, for a MOD IN input
of 5V the output power will vary depending on the operating temperature. Also, in order to eliminate
a “dead zone” in the LD PWR ADJ pot, the output of the unit is offset to the threshold current of the
coupled laser diode. That is, when the LD PWR ADJ pot is full counter clockwise the drive current is
not zero but actually I threshold. Keep this in mind when using the MOD IN input.
 Connect a signal generator or 0 – 5V power source to the unit using a BNC type connector.
 Set the LD PWR ADJ pot on the front panel to its full counter clockwise setting.
 Press the ENABLE switch to turn on the Laser, wait for the “safety delay” to time out.
 Apply the appropriate signal to the MOD IN input. Signals above approximately 5.5V will be clamped
by internal circuits.
 Adjusting the LD PWR ADJ pot will allow for a DC offset on the modulated output. Adjust the input
signal accordingly to avoid clipping the output waveform, which will occur if the unit is driven to its
current or power limits.
 DO NOT apply TTL or squarewave inputs to the MOD IN input. Due to response delays of the
constant current control loop damage to the integrated fiber coupled laser may occur!

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Making the Safety Interlock Connections
The S1 and S3 series Laser Sources are equipped with a Remote Interlock connector located on the rear
panel (Refer to Figure 2). All units have this feature regardless of their FDA and IEC classifications. In
order to enable the laser source, a short circuit must be applied across the terminals of the Remote
Interlock connector. In practice this connection is made available to allow the user to connect a remote
actuated switch to the connector (i.e. an open door indicator). The switch (which must be normally open)
has to be closed in order for the unit to be enabled. Once the switch is in an open state the Laser Source
will automatically shutdown. If the switch returns to a closed condition the Laser Source must be re-
enabled at the unit by pressing the ENABLE switch.
All units shipped from Thorlabs are configured with a shorting device installed in the Interlock connector.
If you are not going to use this feature then you can leave the shorting device installed and the unit will
operate normally as described in the procedures above.
If you wish to make use of the Interlock feature you will need to acquire the appropriate connector mate
and wire it your remote interlock switch. Next, remove the shorting device by pulling it out with a pair of
needle nose pliers and install the connector into the Interlock input.
The Interlock input only accepts a 2.5mm mono phono jack. This connector is readily available at most
electronics stores (Radio Shack, Digikey, Mouser, Allied to name a few).
The electrical specifications for the Interlock input are as follows:
Type of Mating Connector: 2.5mm mono phono jack
Open Circuit Voltage: +5VDC with respect to Chassis ground
Short Circuit Current: 0.5mADC
Connector Polarity: Tip is +5V, Barrel is ground
Interlock Switch Requirements: Must be N.O. dry contacts (under no circumstances should any external
voltages be applied to the Interlock input)
Figure 4 - Remote Interlock Connector
Ground

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Maximizing the Stability of the S3 Series DFB Laser Source
The S3 Series DFB Laser Source provides the ability to control not
only the output power of the fiber coupled laser diode, it also allows for
the precise control of the temperature at which the laser is operating.
These two controls can be used to “tune” the fiber coupled laser diode
to an optimum operating point, providing as stable an output as
possible.
To understand the relationship between the laser diode operating
current, operating temperature, and stability refer to the optical
spectrum analyzer plots of a typical S3FC1550 Laser Source provided
on this page and the next.
To your left, reading from top to bottom is shown the effect of changing
the operating current of the laser while maintaining a fixed operating
temperature (in this case 24.5C). The first plot corresponds to a drive
current of 75% of maximum. Notice the broad line width, the laser is
not optimized but the output will appear to be stable. The next plot is
at 80% drive current. The laser is approaching a stable point but is not
quite there yet as indicated by the second mode. At this point the laser
will toggle between this mode and the previous mode, resulting in
erratic performance. The power display of the unit will typically bounce
between a number of different levels. The third plot down is at 85%
current and is typical of an optimized DFB output; a single, very narrow
line width and very stable power. The last two plots, taken at 90% and
95% currents shows the laser passing through the optimum point and
starting to ebb again.
The five plots on the following page showing the relationship of
temperature vs. stability. With the drive current fixed at 85% of
maximum, the operating temperature was increased by 0.1C per plot,
starting at 24.3C. Viewing the top most plot (24.3C) the laser is once
again not optimized but may appear to be stable. As the temperature
is increased to 24.4C the laser enters a transition point between
modes. At this point the laser may toggle between these modes,
resulting in erratic output. At 24.5C the laser has reached a stable
operating point, indicated by the single narrow line width. The last two
plots (@ 24.7C and 24.9C) show the laser passing through the
optimum point and ebbing again. The range of temperature that will
yield favorable conditions at this drive current is therefore between
24.45C and 24.65C, ideally 24.50C.
Some important points to add here are:
1) This is not the only setting capable of stable operation, there are
many and,
2) This combination of temperature and current may not produce
stable operation in a different unit.
In both of the above examples (fixed temp. or fixed current) the
instabilities are a direct result of the effect that current or temperature
has on the peak wavelength of the laser, shifting it ever so slightly into
regions that don’t support good lasing.
75% Current
1547.993nm
80% Current
1548.834nm
85% Current
1548.834nm
90% Current
1548.839nm
95% Current
1548.839nm

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How to tune your Laser Source to the most optimum power:
So what does all this mean? It means that through careful use of both
the laser diode power control and laser diode temperature control you
will be able to tune your unit to provide the most stable output. Ideally
this procedure should be done using an Optical Spectrum Analyzer
(OSA), however, lacking one you should be able to tune the unit using
the power display on the front panel of the laser source.
Using an OSA:
Step 1 – Let the unit warm up for at least 5 minutes at approximately
the target output power and temperature.
Step 2 – While monitoring the output on the OSA determine the quality
of the output based on the samples shown in the plots to the left.
Step 3 – Adjust the temperature controller in 0.1C steps until you
have passed through an ideal operating point.
Step 4 – Determine the mid-point of the favorable temperature range
and set the temperature to that point.
Step 5 – Do not change the power set point, doing so will affect the
tuning.
Step 6 – Record the power and temperature set points. These
settings are repeatable when used in an ambient temperature within
+/-10 C of the original tuning. To use recorded settings it is best to
set the temperature and allow it to settle, then set the power.
Using the Power Display:
Step 1 - Let the unit warm up for at least 5 minutes at approximately
the target output power and temperature.
Step 2 – Record the temperature set point and power set point.
Step 3 – Increase the temperature by 0.1C, record the output power
as displayed on the front panel meter.
Step 4 – Repeat Step 3 at least 8 to 10 more times, recording the
output power after each step.
Step 5 – Looking at the changes in output power you should observe a
trend of the power increasing-decreasing-increasing over the course
of the temperature range (or visa-versa depending on the initial
stability).
Step 6 – Determine the temperature that corresponds to a maximum
power trend in Step 5 and set the unit to this point.
Step 7 – Do not change the power set point, doing so will affect the
tuning.
Step 8 - Record the power and temperature set points. These settings
are repeatable when used in an ambient temperature within +/-10 C
of the original tuning. To use recorded settings it is best to set the
temperature and allow it to settle, then set the power.
24.3C
1547.994nm
24.4C
1548.830nm
24.5C
1548.834nm
24.7C
1548.839nm
24.9C
1548.839nm

2298-D11e.DOC REV. E 9/5/03 Page 11 of 12
CAUTION- use of controls or adjustments or performance of procedures other than those specified
herein may result in hazardous radiation exposure.
This product complies with 21 CFR 1040.10 and 1040.11 except for deviations pursuant to Laser Notice
No. 50, dated May 27, 2001.
Class 1 Laser Product
1310nm <5mW
Class 1 Laser Product
1550nm <5mW
Laser Radiation
Do Not Stare Into Beam
Class 3R Laser Product
600-700nm <5mW
Invisible Laser Radiation
Avoid Direct Eye Exposure
Class 3B Laser Product
700-800nm <50mW