THORLABS PDA100A User manual

PDA100A(-EC)
Si Switchable Gain
Detector
User Guide

Si Amplified Detector with Switch Gain
Table of Contents
Chapter 1Warning Symbol Definitions ...........................................1
Chapter 2Description........................................................................2
Chapter 3Setup.................................................................................. 3
Chapter 4Operation...........................................................................4
4.1.TheoryofOperation.......................................................4
4.2.Responsivity..................................................................4
4.3.DarkCurrent..................................................................5
4.4.BandwidthandResponse...............................................5
4.5.TerminatingResistance..................................................6
4.6.GainAdjustment............................................................6
Chapter 5Trouble Shooting..............................................................7
Chapter 6Specifications ...................................................................8
6.1.ResponseCurve............................................................10
6.2.MechanicalDrawing....................................................11
Chapter 7Certificate of Conformance ...........................................12
Chapter 8Regulatory.......................................................................13
Chapter 9Thorlabs Worldwide Contacts.......................................14

Si Amplified Detector with Switch Gain Chapter 1: Warning Symbol Definitions
Rev F, June 30, 2017 Page 1
Chapter 1 Warning Symbol Definitions
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: Laser Radiation
Caution: ESD Sensitive Components

Si Amplified Detector with Switch Gain Chapter 2: Description
Page 2 13055-D03
Chapter 2 Description
The PDA100A(-EC) is an amplified, switchable-gain, Silicon (Si) detector designed
for detection of light signals ranging from 340 nm to 1100 nm. An eight-position
rotary switch allows the user to vary the gain in 10 dB steps. A buffered output
drives 50 load impedances up to 5 V. The PDA100A(-EC) housing includes a
removable threaded coupler (SM1T1) and retainer ring (SM1RR) that is compatible
with any number of Thorlabs 1” threaded accessories. This allows convenient
mounting of external optics, light filters, apertures, as well as providing an easy
mounting mechanism using Thorlabs’ cage assembly accessories. Also included
is a ±12 V power supply.
ESD Caution
The components inside this instrument are ESD sensitive. Take all appropriate
precautions to discharge personnel and equipment before making any electrical
connections to the unit.

Si Amplified Detector with Switch Gain Chapter 3: Setup
Rev F, June 30, 2017 Page 3
Chapter 3 Setup
The detector can be set up in many different ways using our extensive line of
adapters. However, the detector should always be mounted and secured for best
operation.
1. Unpack the optical head, install a Thorlabs TR-series ½" diameter post
into one of the #8-32 (M4 on -EC version) tapped holes, located on the
bottom and side of the head, and mount into a PH-series post holder.
2. Connect the power supply 3-pin plug into the power receptacle on the
PDA100A(-EC).
3. Plug the power supply into a 50 to 60Hz, 100 to 120 VAC outlet (220 to
240 VAC for –EC version).
4. Attach a 50 coax cable (i.e. RG-58U) to the output of the PDA. When
running cable lengths longer than 12" we recommend terminating the
opposite end of the coax with a 50 resistor (Thorlabs p/n T4119) for
maximum performance. Connect the remaining end to a measurement
device such as an oscilloscope or high speed DAQ card. Caution: Many
high speed oscilloscopes have input impedances of 50 . In this case,
do not install a 50 terminator. The combined loads will equal 25 
which could allow ~135 mA of output current. This will damage the output
driver of the PDA100A(-EC).
5. Power the PDA100A(-EC) on using power switch located on top side of
unit.
CAUTION
The PDA100A(-EC) was designed to allow maximum accessibility to the
photodetector by having the front surface of the diode flush with the outside of
the PDA housing. When using fiber adapters, make sure that the fiber ferrule
does not crash into the detector. Failure to do so may cause damage to the
diode and or the fiber. An easy way to accomplish this is to install a SM1RR
retaining ring [included with the PDA100A(-EC)] inside the 1" threaded coupler
before installing the fiber adapter.
6. Install any desired filters, optics, adapters, or fiber adapters to the input
aperture.
7. During alignment, take appropriate precautions, such as using reduced
radiation power, or other precautions, and use proper eye and/or skin
protection as recommended by the radiation source manufacturer.
8. Apply a light source to the detector. Adjust the gain to the desired setting.
! !

Si Amplified Detector with Switch Gain Chapter 4: Operation
Page 4 13055-D03
Chapter 4 Operation
4.1. Theory of Operation
Thorlabs PDA series are ideal for measuring both pulsed and CW light sources.
The PDA100A(-EC) includes a reverse-biased PIN photo diode, mated to a
switchable gain transimpedance amplifier, and packaged in a rugged housing.
4.2. Responsivity
The responsivity of a photodiode can be defined as a ratio of generated
photocurrent (IPD) to the incident light power (P) at a given wavelength:
󰇛󰇜

Photodetector
Transimpedance Amp
Out
Feedback
R
F
A
B
-V
BNC
GND
GND GND
R
LOAD

Si Amplified Detector with Switch Gain Chapter 4: Operation
Rev F, June 30, 2017 Page 5
4.3. Dark Current
Dark current is leakage current which flows when a bias voltage is applied to a
photodiode. The PDA with Transimpedance Amplifier does control the dark current
flowing out. Looking at the figure above, it can be noted that Point B is held at
ground and the amplifier will try to hold point A to “Virtual Ground”. This minimizes
the effects of dark current present in the system.
The dark current present is also affected by the photodiode material and the size
of the active area. Silicon devices generally produce low dark current compared to
germanium devices which have high dark currents. The table below lists several
photodiode materials and their relative dark currents, speeds, sensitivity, and
costs.
Material Dark
Current Speed Sensitivity1 (nm) Cost
Silicon (Si) Low High 400 – 1000 Low
Germanium (Ge) High Low 900 – 1600 Low
Gallium Phosphide
(GaP) Low High 150 – 550 Med
Indium Gallium Arsenide
(InGaAs) Low High 800 – 1800 Med
Extended Range: Indium
Gallium Arsenide
(InGaAs)
High High 1200 – 2600 High
4.4. Bandwidth and Response
A load resistor will react with the photodetector junction capacitance to limit the
bandwidth. For best frequency response, a 50 terminator should be used in
conjunction with a 50 coaxial cable. The gain of the detector is dependent on
the feedback element (RF). The bandwidth of the detector can be calculated using
the following:
󰇛3󰇜
4
Where GBP is the amplifier gain bandwidth product and CDis the sum of the
photodiode junction capacitance and the amplifier capacitance.
1Approximate values; actual wavelength values will vary from unit to unit.

Si Amplified Detector with Switch Gain Chapter 4: Operation
Page 6 13055-D03
4.5. Terminating Resistance
A load resistance is used to convert the generated photocurrent into a voltage
(VOUT) for viewing on an oscilloscope:
Depending on the type of the photodiode, load resistance can affect the response
speed. For maximum bandwidth, we recommend using a 50 coaxial cable with
a 50 terminating resistor at the opposite end of the cable. This will minimize
ringing by matching the cable with its characteristic impedance. If bandwidth is not
important, you may increase the amount of voltage for a given light level by
increasing RLOAD. In an unmatched termination the length of the coaxial cable
can have a profound impact on the response, so it is recommended to keep the
cable as short as possible.
The maximum output of the PDA100A(-EC) is 10 volts for high impedance loads
(i.e. RLoad > 5 k) and 5 volts for 50 loads. Adjust the gain so that the measured
signal level out of the PDA100A(-EC) is below 10 volts (5 volts with a 50 load)
to avoid saturation.
For low terminating resistors, <5 kor 1% error, an additional factor needs to be
considered. As described above the output includes a 50series resistor (RS).
The output load creates a voltage divider with the 50series resistor as follows:
 



󰇛󰇜∗∗∗󰇛󰇜
4.6. Gain Adjustment
The PDA100A(-EC) includes a low noise, low offset, high gain transimpedance
amplifier that allows gain adjustment over a 70 dB range. The gain is adjusted by
rotating the gain control knob, located on the top side of the unit. There are 8 gain
positions incremented in 10 dB steps. It is important to note that the bandwidth will
decrease as the gain increases. See the specifications table on page 8 to choose
the best gain verse bandwidth for a given input signal.

Si Amplified Detector with Switch Gain Chapter 5: Trouble Shooting
Rev F, June 30, 2017 Page 7
Chapter 5 Trouble Shooting
Problem Suggested Solutions
There is no signal response.
Verify that the power is switched on and all
connections are secure.
Verify the proper terminating resistor is installed
if using a voltage measurement device.
Verify that the optical signal wavelength is within
the specified wavelength range.
Verify that the optical signal is illuminating the
detector active area.
Output Voltage will not increase.
Detector Output is skewed.
Check to make sure the detector is not
saturated. Refer to the Output Voltage spec.
in the table on page 8.
Install a 1" Lens Tube (SM1L10) to the thread
coulpler (SM1T1) to baffle any external light
sources to see if this improves the response.

Si Amplified Detector with Switch Gain Chapter 6: Specifications
Page 8 13055-D03
Chapter 6 Specifications
All performance specifications are typical, performed at 25 °C ambient
temperature, and assume a 50 load, unless stated otherwise.
2The PDA100A(-EC) has a 50 Ωseries terminator resistor (i.e. in series with amplifier
output). This forms a voltage divider with any load impedance (e.g. 50 Ωload divides
signal in half).
3For NIR wavelengths, the rise time of the photodiode element will become slower which
may limit the effective bandwidth of the amplified detector.
Performance Specifications2
0 dB Setting 40 dB Setting
Gain (Hi-Z) 1.51 x 103V/A ±2% Gain (Hi-Z) 1.51 x 105V/A ±2%
Gain (50 Ω) 0.75 x 103V/A ±2% Gain (50 Ω) 0.75 x 105V/A ±2%
Bandwidth32.4 MHz Bandwidth4 225 kHz
Noise (RMS) 254 V Noise (RMS) 799 V
NEP (@ p) 2.7. x 10-11 W/Hz NEP (@ p) 3.55 x 10-12 W/Hz
Offset ±5 mV (10 mV max) Offset ±8 mV (15 mV max)
10 dB Setting 50 dB Setting
Gain (Hi-Z) 4.75 x 103V/A ±2% Gain (Hi-Z) 4.75 x 105V/A ±2%
Gain (50 Ω) 2.38 x 103V/A ±2% Gain (50 Ω) 2.38 x 105V/A ±2%
Bandwidth41.6 MHz Bandwidth478 kHz
Noise (RMS) 261 V Noise (RMS) 998 V
NEP (@ p) 1.1 x 10-11 W/Hz NEP (@ p) 2.42 x 10-12 W/Hz
Offset ±6 mV (12 mV max) Offset ±8 mV (15 mV max)
20 dB Setting 60 dB Setting
Gain (Hi-Z) 1.5 x 104V/A ±2% Gain (Hi-Z) 1.5 x 106V/A ±5%
Gain (50 Ω) 0.75 x 104V/A ±2% Gain (50 Ω) 0.75 x 106V/A ±5%
Bandwidth4860 kHz Bandwidth420 kHz
Noise (RMS) 349 V Noise (RMS) 1163 V
NEP (@ p) 8.91 x 10-12 W/Hz NEP (@ p) 1.22 x 10-12 W/Hz
Offset ±6 mV (15 mV max) Offset ±8 mV (15 mV max)
30 dB Setting 70 dB Setting
Gain (Hi-Z) 4.75 x 104V/A ±2% Gain (Hi-Z) 4.75 x 106V/A ±5%
Gain (50 Ω) 2.38 x 104V/A ±2% Gain (50 Ω) 2.38 x 106V/A ±5%
Bandwidth4480 kHz Bandwidth45.9 kHz
Noise (RMS) 561 V Noise (RMS) 1490 µV
NEP (@ p) 4.65 x 10-12 W/Hz NEP (@ p) 9.73 x 10-13 W/Hz
Offset ±8 mV (15 mV max) Offset ±30 mV (Max)

Si Amplified Detector with Switch Gain Chapter 6: Specifications
Rev F, June 30, 2017 Page 9
Electrical Specifications
Detector Si PIN
Active Area 10 x 10 mm (100 mm2)
Wavelength Range 340 to 1100 nm
Peak Wavelength p 960 nm (Typ)
Peak Response ( p) 0.62 A/W (Typ)
Amplifier GBP 600 MHz
Output Impedance 50 
Max Ouput Current IOUT 100 mA
Load Impedance 50 to Hi-Z
Gain Adjustment Range 0 to 70 dB
Gain Steps 8 x 10 dB Steps
Output Voltage VOUT 0 to 5 V (50 )
0 to 10 V (Hi-Z)
General
On/Off Switch Slide
Gain Switch 8 Position Rotary
Output BNC (DC Coupled)
Package Size 2.76" x 2.06" x 0.88"
(70.1 mm x 52.3 mm x 22.4 mm)
PD Surface Depth 0.16" (4.1 mm)
Weight, Detector Only 0.15 lbs
Accessories SM1T1 Coupler
SM1RR Retainer Ring
Operating Temp 10 to 40 °C
Storage Temp -20 to 70 °C
AC Power Supply AC – DC Converter
Input Power4
31 W
100 – 200 VAC (50 to 60Hz)
220 – 240 VAC (50 to 60 Hz)
4Although the power supply is rated for 31 W the PDA100A(-EC) actual usage is <5 W
over the full operating range.

Si Amplified Detector with Switch Gain Chapter 6: Specifications
Page 10 13055-D03
6.1. Response Curve
The highlighted region represents the detector’s specified wavelength range.
400 500 600 700 800 900 1000300 1100
0.0
0.2
0.4
0.6
0.8
PDA100A Responsivity
Responsivity (A/W)
Wavelength (nm)

Si Amplified Detector with Switch Gain Chapter 6: Specifications
Rev F, June 30, 2017 Page 11
6.2. Mechanical Drawing
65.3 mm
(2.57")
21.1 mm
(0.83")
19.1 mm
(0.75")
Power Supply
Connection
±12 VDC, 200 mA
Output BNC with
0 - 10 V Range and
50 Ohm Drive Capability
Power LED
A
1.035"-40 External Thread Mates with SM1 Series
53.3 mm
(2.10")
20.1 mm
(0.79")
48.0 mm
(1.89")
43.2 mm
(1.70")
Power Switch
SM1T1 Threaded Coupler with Retaining Ring Included
0.535"-40 Internal Thread Mates with SM05 Series
#8-32 x 0.25" Thread (M4 x 6.35 mm for -EC Version)
26.2 mm
(1.03")
1.00 mm (0.04")
Detector Surface
Detail A
Scale 2:1

Si Amplified Detector with Switch Gain Chapter 7: Certificate of Conformance
Page 12 13055-D03
Chapter 7 Certificate of Conformance

Si Amplified Detector with Switch Gain Chapter 8: Regulatory
Rev F, June 30, 2017 Page 13
Chapter 8 Regulatory
As required by the WEEE (Waste Electrical and Electronic Equipment Directive)
of the European Community and the corresponding national laws, Thorlabs offers
all end users in the EC the possibility to return “end of life” units without incurring
disposal charges.
This offer is valid for Thorlabs electrical and electronic equipment:
Sold after August 13, 2005
Marked correspondingly with the crossed out
“wheelie bin” logo (see right)
Sold to a company or institute within the EC
Currently owned by a company or institute
within the EC
Still complete, not disassembled and not
contaminated
As the WEEE directive applies to self contained
operational electrical and electronic products, this end of
life take back service does not refer to other Thorlabs products, such as:
Pure OEM products, that means assemblies to be built into a unit by the
user (e.g. OEM laser driver cards)
Components
Mechanics and optics
Left over parts of units disassembled by the user (PCB’s, housings etc.).
If you wish to return a Thorlabs unit for waste recovery, please contact Thorlabs or
your nearest dealer for further information.
Waste Treatment is Your Own Responsibility
If you do not return an “end of life” unit to Thorlabs, you must hand it to a company
specialized in waste recovery. Do not dispose of the unit in a litter bin or at a public
waste disposal site.
Ecological Background
It is well known that WEEE pollutes the environment by releasing toxic products
during decomposition. The aim of the European RoHS directive is to reduce the
content of toxic substances in electronic products in the future.
The intent of the WEEE directive is to enforce the recycling of WEEE. A controlled
recycling of end of life products will thereby avoid negative impacts on the
environment.
Wheelie Bin Logo

Si Amplified Detector with Switch Gain Chapter 9: Thorlabs Worldwide Contacts
Page 14 13055-D03
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.
sal[email protected]
[email protected]
Europe
Thorlabs GmbH
[email protected]
France
Thorlabs SAS
[email protected]
Japan
Thorlabs Japan, Inc.
[email protected]
UK and Ireland
Thorlabs Ltd.
[email protected]
[email protected]
Scandinavia
Thorlabs Sweden AB
[email protected]
Brazil
Thorlabs Vendas de Fotônicos Ltda.
[email protected]br
China
Thorlabs China
[email protected]

www.thorlabs.com