THORLABS PDF10A2 User manual

Femtowatt Photoreceiver
PDF10A2
Operation Manual
2020

Version:
Date: 1.0 10-Mar-2020
Copyright © 2020 Thorlabs

Foreword
Contents
1 General Information 1
11.1 Ordering Codes and Accessories
2 Getting Started 2
22.1 Parts List 22.2 Preparation
3 Operating Instruction 3
33.1 Operating Elements 33.2 Mounting 43.3 Operation 53.4 Recommendations 63.5 Operating Principle 63.5.1 Optical Input 63.5.2 Electrical Output
4 Maintenance and Service 7
5 Appendix 8
85.1 Technical Data 95.2 Typical Responsivity 95.3 Typical Frequency Response 105.4 Typical Spectral Noise 105.5 Typical Output Time Response 115.6 Drawings 115.7 Safety 125.8 Return of Devices 125.9 Manufacturer Address 135.10Certifications and Compliances 145.11Warranty 145.12Exclusion of Reliability and Copyright 155.13Thorlabs Worldwide Contacts and WEEE poilicy

© 2020 Thorlabs
We aim to develop and produce the best solutions for your
applications in the field of optical measurement techniques. To help
us to live up to your expectations and constantly improve our
products, we need your ideas and suggestions. We and our
international partners are looking forward to hearing from you.
Thorlabs GmbH
Warning
Sections marked by this symbol explain dangers that might result in
personal injury or death. Always read the associated information
carefully before performing the indicated procedure.
Please read this advice carefully!
This manual also contains "NOTES" and "HINTS" written in this form.
Attention
Paragraphs preceded by this symbol explain hazards that could
damage the instrument and the connected equipment or may cause
loss of data.
Note

© 2020 Thorlabs
1 General Information
1
1 General Information
This Thorlabs PDF10A2 Femtowatt Photoreceiver combines a low-noise silicon photodiode with
a specially designed ultra-low-noise, fixed-gain transimpedance amplifier with extremely high
gain of up to 1012 V/A. This combination results in a photoreceiver with femtowatt sensitivity and
an exceptionally low NEP, making it ideal for low-light level detection applications, such as
spectroscopy and fluorescence measurements. Direct detection of optical power down to ~10
fW is possible. In combination with an optional lock-in amplifier, sub-femtowatt sensitivity can
be achieved.
Due to a very high sensitivity, the PDF10A2 Femtowatt Photoreceiver can replace photomulti-
plier tubes (PMTs), avalanche photodiodes (APDs), and liquid-nitrogen-cooled germanium pho-
todiodes in many applications. No expensive high-voltage power supply or cooling is required.
Another advantage is that the PDF10A2 cannot be damaged by unwanted ambient light, which
is critical for many photomultiplier tubes.
The PDF10A2 detector housing can be integrated in optical setups using convenient 8-32 and
M4 combi-thread mounting holes that are compatible with both imperial and metric threading.
Please see the chapter Mounting for details.
The housing accommodates Thorlabs' SM05 (0.535"-40) and SM1 (1.035"-40) threaded adap-
ters and accessories. This allows convenient mounting of external optics, light filters, and aper-
tures. The product includes an SM1 Coupler Body (SM1T1), which adapts the external thread
to an internal thread and holds the SM1RR Retaining Ring, and a reusable protective plastic
cover cap. For accessories, please visit our website or contact Thorlabs .
A ±12 VDC power supply is included with each amplified photodetector. The appropriate input
voltage (100 VAC, 120 VAC, 230 VAC) can be selected with a switch on the power supply .
Attention
Please find all safety information and warnings concerning this product in the chapter Safety
in the Appendix.
1.1 Ordering Codes and Accessories
PDF10A2 Femtowatt Photoreceiver, Silicon detector, 320 - 1100nm, Bandwidth DC-20Hz,
Square Active Area 1.2 mm2 (1.1 mm x 1.1 mm), Combi-Thread Mounting Holes
Compatible with 8-32 and M4 Threads
Included Accessories
·LDS12B Power Supply (±12V, 0.2A), 100 VAC, 120 VAC or 230 VAC Line Voltage
·Plastic Cover Cap (Item # SM1EC2B) on an included SM1T1 SM1 Coupler with a SM1RR
SM1 Retaining Ring.
Optional Accessories
·All Thorlabs internal SM1 (1.035"-40) and external SM05 (0.535"-40) threaded accessories
are compatible with the PDF10A2.
·Fiber adapter of the Thorlabs S120-xx. These fiber adapter can be mounted on the optical in-
put for fiber coupled applications.
·PDA-C-72 DC power supply cable to PDF10A2: This cable has a connector on one end and
open wires at the other. The pin-out of the PDF10A2 DC power jack is shown in the ap-
pendix .
Please visit our homepage http://www.thorlabs.com for various accessories like fiber adapters,
posts and post holders, data sheets and further information.
3
15
2
11
11

© 2020 Thorlabs2
PDF10A2
2 Getting Started
2.1 Parts List
Please inspect the shipping container for damage. Do not cut through the cardboard. You might
need the box for storage or returns.
If the shipping container seems to be damaged, keep it until you have inspected the contents
mechanically and electrically.
Verify that you have received the following items within the package:
1. PDF10A2 Amplified Photodetector
2. Plastic Cover Cap (Item # SM1EC2B) on SM1T1-SM1 Coupler with an SM1RR-SM1 Re-
taining Ring
3. LDS12B Power Supply (±12V, 0.2A), 100 VAC, 120 VAC or 230 VAC Line Voltage
4. Quick Reference
2.2 Preparation
Carefully unpack the unit and accessories. If any damage is noticed, do not use the unit.
Contact Thorlabs and have us replace the defective unit.
Note
Prior to operation, please check if the indicated line voltage range on the power supply matches
with your local mains voltage! Adjust the power supply accordingly to 100 VAC, 120 VAC or
230 VAC.
Note
If you prefer to use your own power supply, please ask Thorlabs for an appropriate power
connector cable .
15
15
1

© 2020 Thorlabs
3 Operating Instruction
3
3 Operating Instruction
3.1 Operating Elements
PDF10A2
3.2 Mounting
Housing
The PDF10A2 is housed in a rugged, shielded, 70.9 mm x 49.9 mm x 22.5 mm aluminum en-
closure.
Mounting PDF10A2 on an Optical Table
Mount the PDF10A2 on an optical post by using either of the two tapped mounting holes on the
side and bottom. The combi-thread tapped holes accept both 8-32 and M4 threads, such that
using either imperial or metric TR posts is possible.
Mounting External Optics
The PDF10A2 housing accommodates Thorlabs’ SM05-threaded (0.535"-40) and SM1-
threaded (1.035"-40) adapters that are compatible with any number of Thorlabs 1” and ½”
threaded accessories. This allows to mount external optics, filters, apertures, fiber adapters,
lens tubes, or cage systems. For accessories, please visit our website or contact Thorlabs .
The PDF10A2 comes with an SM1T1 SM1 coupler that adapts the external thread to an SM1
internal thread. A retaining ring in the coupler holds the protective cover cap. Please unscrew
the coupler if needed.
15

© 2020 Thorlabs4
PDF10A2
3.3 Operation
Attention
Ensure that the correct mains voltage is selected on the power supply prior to connecting the
power supply to the mains power. Wrong settings for the mains voltage may damage the power
supply. The ±12 V, 250 mA power supply is included; no high voltage power supply is required
for operation.
Attention
Refer to the Technical Data and pay attention to the optical damage threshold of 10 mW!
Exceeding this value will permanently destroy the detectors!
Attention
Due to limitations in the IC, the high-speed amplifier used in these devices may become un-
stable, exhibiting oscillations or negative output, if the power supply voltage is applied when the
module is on. Therefore, please make sure the power-on switch on your PDF10A2 is in OFF
position 0 (see Operating Elements ) prior to connecting the external power supply.
Electrical Setup
·Mount the detector using the combi-thread mounting holes on the side and bottom of the
device.
·Make sure the PDF10A2 is switched off.
·Plug the power connector cable into the DC INPUT LDS12B connector of the PDF10A2.
·Plug the power supply into an outlet.
·Connect OUTPUT to your data acquisition device with a coaxial cable. The PDF10A2 with
femtowatt sensitivity is a low-frequency device that should only be terminated into high impe-
dance (Hi-Z) loads.
·Switch on the power supply.
·Switch on the PDF10A2 by moving the power slider to I while the optical input is protected by
the cover cap.
·The maximum OUTPUT voltage swing is ±10 V for high impedance loads (>10 kW). The
OUTPUT signal should stay below this maximum output voltage to avoid amplifier saturation.
Optical Setup
·Ensure that OUTPUT offset voltage is within the range listed in Technical Data . A small
drift during the warm up period (~5 min) is typical.
·Check whether the noise level is below 5 mVRMS. If the noise level is significantly higher,
please refer to recommendations and optimize your setup.
·Remove the plastic cover cap that protects the optical input.
·Mount external optics if needed.
·Align the light source with the optical input.
·It is recommended to focus the optical signal out of the fiber onto the detector.
·To prevent saturation of the amplifier keep the optical input powers below the CW saturation
power listed in Technical Data . External neutral density filters or attenuators are recom-
mended to reduce the input light level in critical cases.
·For maximum linearity performance and to prevent damage to the detector when measuring
focused beams, fiber outputs, or small diameter beams, do not exceed a maximum input
power of 10 mW/cm2.
Turning off the PDF10A2
Move the power slider to 0after finishing the measurements.
2
8
3
3
8
5
3
5
8

© 2020 Thorlabs
3 Operating Instruction
5
3.4 Recommendations
·Optical Alignment
oAn open beam should always be carefully aligned with the detector. Due to the small active
area of the PDF10A2 photodiodes, it is recommended to focus the optical signal out of a
fiber onto the detector. For this and other fiber-coupled applications, fiber adapters like
Thorlabs S120-xx series can be mounted on the optical input. The fiber adapters accom-
modate multi-mode or single-mode fibers.
oPlease note that coupling losses may occur due to the small detector size. This will result in
a reduced output signal. If angled connectors are used, an FC adapter can be rotated from
its original position to improve the alignment. For this process apply an input signal with
power below the saturation level while observing the output voltage using a digital voltmeter
or other low-frequency measurement device.
·Ambient or stray light
oPDF10A2 photodetectors are extremely sensitive devices. To reduce the noise level, careful
shielding of the PDF10A2 from any unwanted light sources is essential. Common tech-
niques are baffling or other opaque barriers like black cloths or beam tubes. Even a small
power-on indicator LED far away from the PDF10A2 can affect power measurements at
femtowatt levels.
oIt is not necessary to switch off the PDF10A2 when it is exposed to ambient light. The amp-
lifier will saturate but, unlike photomultiplier tubes, it will not be damaged or saturated for a
long period of time.
oIt is highly recommended to use appropriate bandpass filters in front of the detector to mini-
mize the influence of stray light.
·High Optical Input Power
oTo avoid permanent damage to the detector, do not exceed the specified optical damage
threshold of 10 mW as specified in section Technical Data .
oKeep the optical input power below the CW saturation power listed in the Technical Data
to avoid electrical saturation.
·Amplifier Saturation
To avoid electrical saturation of the amplifier keep the output voltage Vout below the maximum
listed in Technical Data . External neutral density filters or attenuators are recommended to
reduce the input light level in critical cases.
·Electrostatic Coupling
Electrostatic coupling of electrical noise associated with ground loops can be critical. In most
cases an electrically isolated post (e.g. Thorlabs item# TRE or TRE/M) will suppress elec-
trical noise coupling. Always try to identify electrical noise sources and increase the distance
to the PDF10A2. If possible, rotate the PDF10A2 input away from the noise source. Different
common ground points can also be tested.
·Impact of Temperature
oThe amplifier offset voltage is factory set to zero at 23 °C ambient temperature. Due to the
very high transimpedance gain, even small temperature changes or even humidity changes
may affect the offset voltage. Therefore it is recommended for precise DC light level mea-
surements to use the PDF10A2 in an environment with constant temperature after a short
warm up period (~5 min).
8
8
8

© 2020 Thorlabs6
PDF10A2
3.5 Operating Principle
The Thorlabs PDF10A2 Femtowatt Photoreceiver combines a low noise Silicon photodiode with
a specially designed ultra low noise transimpedance amplifier with extremely high gain. This
unique combination results in a photoreceiver with femtowatt sensitivity due to the exceptional
low NEP and makes it ideal for low-light level detection applications, such as spectroscopy and
fluorescence measurements. Direct detection of optical power down to ~10 fW is possible.
3.5.1 Optical Input
Optical Beam Alignment
The PDF10A2 uses a Silicon Photodiode with a square detector active area of 1.2 2 (1.1 mm x
1.1 mm).
Due to this small active area of the PDF10A2 photodiodes, it is recommended to focus the op-
tical signal out of the fiber onto the detector.
Because the housing is compatible with any number of Thorlabs 1” and ½” threaded accessor-
ies, external optics, filters or apertures can be easily attached to the PDF10A2.
Detector Sensitivity
The PDF10A2 and PDF10C2 are specified for determined wavelength ranges . The typical
responsivity curves can be found in the appendix . Please note that these femtowatt photore-
ceivers are extremely sensitive to unwanted stray light.
3.5.2 Electrical Output
Responsivity
The Thorlabs PDF10A2 detectors deliver an output voltage, which is a function of incident light
power POPT, detector responsivity Â(l) and transimpedance gain G given by:
l × ×OUT OPTV =P ( ) G
The responsivity Â(l) for a given wavelength can be read from the diagrams Typical Responsi-
vity to estimate the output voltage. Please note that transimpedance gain tolerance is ±10%
for an individual unit due to extremely high feedback resistors used for the transimpedance
amplifier. Temperature changes or even humidity changes may affect transimpedance gain.
Output Voltage
The maximum output voltage is 10 V for high impedance loads (>10 kW). The output signal
should stay below the maximum output voltage to avoid saturation. Depending on wavelength
responsivity Â(l) of the detector, the amplifier will reach saturation at optical input power greater
than CW Saturation Power listed in Technical Data .
Note
Typical curves for the Frequency Response , Spectral Noise Distribution and Output Time
Response can be found in the appendix.
8
9
9
8
9 10
10