THORLABS PDFA100 User manual

PDFA100
O-Band Praseodymium
Doped Fiber Amplifier
Operating Manual

Fiber Amplifier
Table of Contents
Warning Symbol Definitions..............................................................................................1
Safety....................................................................................................................................2
Description...........................................................................................................................4
3.1.Shipping List....................................................................................................................4
Setup.....................................................................................................................................5
4.1.Setting the AC Line Voltage ...........................................................................................5
4.2.Changing the Fuse ..........................................................................................................5
4.3.Initial Setup ......................................................................................................................5
Operation from Instrument Front Panel...........................................................................6
5.1.Front and Back Panel Overview.....................................................................................6
5.2.Turning On the Amplifier ................................................................................................7
5.3.Adjusting the Fiber Amplifier Gain ................................................................................7
5.4.Turning the Fiber Amplifier Off ......................................................................................7
Remote Operation from Command-Line Interface.........................................................8
Making Safety Interlock Connections..............................................................................9
Troubleshooting.................................................................................................................10
General Maintenance.........................................................................................................11
9.1.Cleaning .........................................................................................................................11
9.2.Connector Cleaning ......................................................................................................11
Specifications.....................................................................................................................12
Mechanical Drawings.........................................................................................................14
Regulatory...........................................................................................................................15
12.1.Waste Treatment is Your Own Responsibility............................................................15
12.2.Ecological Background ................................................................................................15
Declaration of Conformity.................................................................................................16
Thorlabs Worldwide Contacts..........................................................................................17

Fiber Amplifier Chapter 1: Warning Symbol Definitions
Rev C, March 9, 2020 Page 1
Warning Symbol Definitions
Note: Throughout this manual, references to temperature are with respect to °C.
Below is a list of warning symbols you may encounter in this manual or on your device.
Symbol Description
Direct Current
Alternating Current
Both Direct and Alternating Current
Earth Ground Terminal
Protective Conductor Terminal
Frame or Chassis Terminal
Equipotentiality
On (Supply)
Off (Supply)
In Position of a Bi-Stable Push Control
Out Position of a Bi-Stable Push Control
Caution: Risk of Electric Shock
Caution: Hot Surface
Caution: Risk of Danger
Warning: Visible or Invisible Laser Radiation
Caution: Spinning Blades May Cause Harm

Fiber Amplifier Chapter 2: Safety
Page 2 TTN190684-D02
Safety
All statements regarding safety of operation and technical data in this instruction manual will only apply when the
unit is operated correctly.
SHOCK WARNING
High voltage inside. To avoid electrical shock, before powering the unit on, make sure that the
protective conductor of the 3-conductor power cord is correctly connected to the protective earth
contact of the socket outlet. Improper grounding can cause electric shock resulting in severe injury
or even death. Do not operate without cover installed.
EXPLOSION WARNING
This instrument must not be operated in an explosion endangered environment.
LASER WARNING
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
Note: This equipment has been tested and found to comply with the limits for a Class B digital
device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable
protection against harmful interference in a residential 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. If this equipment does cause
harmful interference to radio or television reception, which can be determined by turning the
equipment off and on, the user is encouraged to try to correct the interference by one or more of the
following measures: Reorient or relocate the receiving antenna.—Increase the separation between
the equipment and receiver.—Connect the equipment into an outlet on a circuit different from that to
which the receiver is connected.—Consult the dealer or an experienced radio/TV technician for help.
CAUTION
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.

Fiber Amplifier Chapter 2: Safety
Rev C, March 9, 2020 Page 3
The unit is supplied with a region-specific power cord. If using your own power cord, make sure it is IEC 320
compatible.
Make sure that the line voltage rating marked on the rear panel agrees with your local supply and that the
appropriate fuses are installed. Changing of the mains fuse can be done by the user (see Section 4.2, Changing
the Fuse). With the exception of the mains fuses, there are no user serviceable parts in this product.
Do not operate in wet or damp conditions. Do not obstruct the air ventilation slots in the housing!
This device can only be returned when packed into the complete original packaging, including all foam packing
inserts. If necessary, ask for a replacement package.
Mobile telephones, cellular phones, or other radio transmitters should not to be used within the range of three
meters of this unit since the electromagnetic field intensity may exceed the maximum allowed disturbance values
according to EN50082-1.

Fiber Amplifier Chapter 3: Description
Page 4 TTN190684-D02
Description
Thorlabs' Praseodymium-Doped Fiber Amplifier (PDFA) offers high gain, high saturation power, and a low noise
figure, making it ideal for use within optical networks as either a booster amplifier or preamplifier. The fiber amplifier
technology offers an alternative to semiconductor amplifiers (SOAs) with improved optical performance by
eliminating the signal distortions typically associated with gain saturation in SOA devices. Each fiber amplifier is
enclosed in a compact, turnkey benchtop package with FC/APC (2.0 mm narrow key) input and output connectors.
The system integrates a pump laser and precision current driver to adjust the pump power in the amplifier. The
current adjustment, done through an adjustment knob on the front panel, varies the amplifier gain. The amplifier
includes input and output isolators to protect the input laser source from any amplified spontaneous emission or
back reflections, as well as to prevent the pump light from exiting the amplifier.
The PDFA gain can be controlled in constant current control (ACC) mode via the front panel interface. The pump
current of the amplifier is adjustable through the instrument's front panel, allowing the user to vary the gain and
output power. The display screen shows the pump level, as well as the temperature and emission status. An
indicator light is also included on the enable button to show when the internal laser is active. In addition to this mode
of operation, the PDFA can be operated in constant power control (APC) and constant gain control (AGC) modes
using a command-line interface via USB connection with a PC. These modes of operation allow the user to control
the amplifier for a fixed output power level or a fixed gain value. The amplifier automatically adjusts the pump current
in order to maintain the power or gain target values. For further information regarding all three modes of operation,
please see Chapter 5.
For added safety, there is an interlock connector located on the rear panel that must be shorted in order for the
output to be enabled. This can easily be configured to be triggered by doors to disable the fiber amplifier in unsafe
conditions. An enable button must be set to activate the amplifier, and a green LED indicator displays the current
state of the unit. There is a 3 second delay before the fiber amplifier turns on, and the user is warned by the rapidly
blinking LED.
The amplifier includes a universal power supply allowing operation over 100 to 240 VAC without the need for
selecting the line voltage. The fuse access is conveniently located on the rear panel.
3.1. Shipping List
The PDFA100 consists of the following components:
 O-Band Praseodymium-Doped Fiber Amplifier in Benchtop Package
 Interlock-Shorting BNC Connector
 Region-Specific Power Cord
 USB Cable
 FBC250 Connector and Bulkhead Cleaner

Fiber Amplifier Chapter 4: Setup
Rev C, March 9, 2020 Page 5
Setup
CAUTION
Prior to using the PDFA systems, it is highly recommended to clean the input and output bulkheads
as well as the connector facets to be connected to the bulkheads. Failure to clean the connectors
can result in damage to the internal connectors in the PDFA as well as the connectors on fiber
patch cables connected to the PDFA.
When cleaning the connectors, ensure that the PDFA is powered off by turning off the push-button
switch. Never inspect optical connectors unless all light sources in your setup have been switched
off. Please refer to Section 9.2 for further instructions regarding connector cleaning.
4.1. Setting the AC Line Voltage
The fiber amplifier has been shipped configured for 100 to 240 VAC operation. There is no end user adjustment of
the line voltage for 110 or 220 VAC. The user needs to select the correct AC cord for their location.
4.2. Changing the Fuse
To change the power fuse, follow the following steps.
1. Remove the AC power cord if it is connected to the unit.
2. Locate the fuse tray directly adjacent to the AC power cord connection on the rear panel of the unit.
3. Carefully use a flat blade screwdriver to open the fuse tray.
4. Remove the existing fuses and install two fuses with the appropriate specifications. The replacement fuses
must be 5 mm x 20 mm, 2 A, 250 VAC, slow-blow type.
5. Push the fuse tray back into place making sure that it snaps and sits correctly.
6. Connect the appropriate power cord into the AC receptacle and plug the unit in.
4.3. Initial Setup
1. Set the unit on a dry, level working surface.
2. Plug the female end of the provided AC line cord into the IEC input receptacle on the rear of the unit. Plug
the male end into a properly grounded AC socket.
3. Install the interlock BNC connector. (See page 8 for details on the interlock circuitry.)
4. Connect the input to be amplified to the input fiber receptacle using a FC/APC fiber patch cable, carefully
cleaning both the input FC bulkhead connector and the patch cable connector beforehand. Please note that
a standard single mode (SM) cable should be used for the PDFA100, and that the input power entering the
amplifier should not exceed 10 dBm (10 mW).
5. Carefully clean both the output FC bulkhead connector and the connectors on both ends of a second
FC/APC patch cable. Connect one end of the cable to the output receptacle on the unit. Connect the other
end to a power meter or another measurement instrument. The output power from the amplifier – when
observing the 10 dBm (10 mW) input power limit – is guaranteed not to exceed 150 mW. Care should be
taken to avoid damage to the measurement instrument connected to the output port. Also note that when
the amplifier is enabled, it generates amplified spontaneous emission even when there is no input light
entering the amplifier. This should be considered when connecting measurement instruments to the output
port of the amplifier and when inspecting the fiber connectors.

Fiber Amplifier Chapter 5: Operation from Instrument Front Panel
Page 6 TTN190684-D02
Operation from Instrument Front Panel
5.1. Front and Back Panel Overview
Figure 1 Front and Rear Panels of the Fiber Amplifier (PDFA100)
Amplifier Input Port
FC/APC Bulkhead
Pump Current Adjustment Knob
Push to adjust.
Push-Button Power Switch
Display
Indicates pump current level (0-100%),
temperature status, and emission status.
Remote Interlock Input (BNC)
See page 9 for connection logic.
USB Port
Communication Port fo
r
Diagnostics and Remote
Interface
Fuse Tray
See Section 4.2 for
replacement details.
Amplifier Output Por
t
FC/APC Bulkhead
AC Power Cord
Connector
Cooling Fan - Do Not Block
Moves air from vent holes on the bottom and sides.
Periodically remove dust buildup from vents for
best operation.
AC Power On/Off
Switch
Enable Switch
and Emission
Indicator

Fiber Amplifier Chapter 5: Operation from Instrument Front Panel
Rev C, March 9, 2020 Page 7
5.2. Turning On the Amplifier
1. Please consult with your organization’s laser safety officer regarding proper operation of the amplifier at
your institution.
LASER WARNING
The amplifier generates invisible amplified spontaneous emission (ASE) even without any optical
input. The power level of the ASE can be as high as 30 mW. Therefore, all laser safety measures
should be followed even if the input light to the amplifier has been disconnected or switched off.
Additionally, it should be noted that connecting a laser to the output port of the amplifier by mistake
can cause damage to the laser due to the ASE light getting coupled into the laser source.
2. Turn on the AC power switch on the back panel.
3. Press the POWER push-button switch. The display will turn on. The pump current set-point (in % of max)
will be displayed in the middle of the screen.
4. Check the temperature status on the bottom left corner of the display. It should show “OK”. If the
temperature status shows “Stabilization” for more than 30 seconds or if it shows “Error”, please turn the
unit off and contact technical support.
5. Check the emission status of the device on the bottom right corner of the screen. It should show “Off” prior
to enabling the amplifier.
6. Make sure the interlock input on the back panel is short-circuited. See Section 6 for detailed instructions.
7. Press and release the ENABLE switch to activate the fiber amplifier. There will be a 3 second delay before
the fiber amplifier powers up. During this time, the ENABLE indicator will light up and blink.
8. Adjust the pump current set-point to the desired value by pressing the adjustment knob once. The “%” sign
blinks in the adjustment mode and it times out after 5 seconds. The knob must be pressed again after the
time-out in order to make additional adjustments to the pump current set-point.
9. Ensure that the temperature status still shows “OK” after the pump current has been increased to the
desired level. The amplifier is now producing gain and is ready to use.
5.3. Adjusting the Fiber Amplifier Gain
The default operation mode of the amplifier is by controlling the pump current. This operation mode is refered to as
the automatic current control (ACC). The fiber amplifier gain and output power are controlled by varying the pump
current set-point. The system specifications represent the performance at max operating set-point (100%). Each
unit is shipped with a test data sheet that shows the amplifier output power at two different input power levels (0
dBm and -30 dBm) as a function of the pump current set-point. The data can be used as a reference to adjust the
pump current set-point for a desired gain level. In addition to the ACC mode of operation, it is possible to operate
the PDFA in automatic power control (APC) and automatic gain control (AGC) modes. These modes of operation
are only accessible through the command-line interface as explained in Chapter 6 of this manual.
5.4. Turning the Fiber Amplifier Off
 Disabling the amplifier emission - The amplifier output can be turned off by pressing and releasing the
ENABLE switch. The pump diode temperature will be maintained even when the amplifier is disabled. The
temperature status should show “OK” after the amplifier has been disabled.
 Power Down - When completely powering down an enabled unit, first press and release the ENABLE
switch and then press the POWER push-button switch, which will turn OFF the entire unit. Anytime the unit
is turned OFF and then turned back ON, the fiber amplifier will be disabled until the ENABLE switch is
pressed. If the amplifier is not being used for an extended period of time, it is recommended to turn off the
AC power using the switch located on the back panel of the instrument. Please note that the pump current
set-point goes back to 0% after each AC power cycle.

Fiber Amplifier Chapter 6: Remote Operation from Command-Line Interface
Page 8 TTN190684-D02
Remote Operation from Command-Line Interface
The Command Line Interface (CLI) provides the user with a method of controlling the PDFA remotely over the
USB interface that is emulating a serial port. A standard terminal program (such as Tera Term) can be used to
send commands to the PDFA and receive responses. The following functions are available through the CLI:
 Enabling and disabling the amplifier emission.
 Reading status indicators
 Setting the current set-point value in the ACC operation mode.
 Operating the system in APC or AGC modes at user-defined power or gain values.
The list below shows the list of available commands along with a brief description and syntax:
Command: Command description:
Help DISPLAY COMMANDS – Lists commands available to the user
le ENABLE LASER – Turns the Pump LASER ON
ld DISABLE LASER - Turns the Pump LASER OFF
sloc SET LASER DIODE OPERATING CURRENT – Sets the Pump LASER output
sloc <current>
Set current is between: 0 to 100 percent
gloc GET LASER DIODE OPERATING CURRENT – Returns the Pump LASER
output
stat STATUS REGISTER – Returns the following status info:
Interlock : Open or Closed
Temp stable: Stable or Unstable
Temp fault : No Fault or Fault
LASER : ON or OFF
runpwr RUN PID POWER CONTROL – Enables the amplifier and starts the PID power
control loop to keep output power constant
runpwr <power>
<power> can be any positive value representing the output power in
micro-Watts
rungain RUN PID GAIN CONTROL – Enables the amplifier and starts the PID gain
control loop to keep the amplifier gain constant
rungain <gain>
<gain> can be any positive value representing the gain value in linear
scale.
Please note that the system default mode is the ACC mode. This mode is accessible by the front panel operation
and the current set point is adjustable using the front panel knob as well as the CLI. The instrument enters this
mode after every power cycle. Enabling the laser from the front panel switch or by executing the “le” command
results in entering the ACC mode of operation. The APC and AGC modes of operation can be activated using the
commands “runpwr” and “rungain”. These commands enable the amplifier and start control loops to maintain a
constant level of output power or gain. The control loops can be interrupted by turning the laser off using the
command “ld”. Alternatively, by setting the power or gain to zero, the control loop is interrupted and amplifier
emission is turned off. If the control loop fails to reach its target under either APC or AGC modes, the closed-loop
operation is automatically terminated and the amplifier id disabled. Upon exiting the control loop, the amplifier goes
back to the default ACC mode.