THORLABS PDA10A User manual

PDA10A(-EC)
Si Amplified Fixed Gain
Detector
User Guide

Si Amplified Fixed Gain Detector
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..................................................5
Chapter 5Troubleshooting ...............................................................7
Chapter 6Specifications ...................................................................8
6.1.ResponseCurve..............................................................9
6.2.MechanicalDrawing....................................................10
Chapter 7Certificate of Conformance ...........................................11
Chapter 8Regulatory.......................................................................12
8.1.WasteTreatmentisYourOwnResponsibility...............12
8.2.EcologicalBackground.................................................12
Chapter 9Thorlabs Worldwide Contacts.......................................13

Si Amplified Fixed Gain Detector Chapter 1: Warning Symbol Definitions
Rev J, September 28, 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 Fixed Gain Detector
Page 2 13054-D02
Chapter 2 Description
The PDA10A(-EC) is an amplified, silicon detector designed for detection of light
signals ranging from 200 to 1100 nm. A buffered output drives 50 load
impedances up to 5 V. The PDA10A(-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.
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.
Caution!
Long-term exposure to high-energy UV light may degrade the performance
and specifications of this Si detector.
!
!

Si Amplified Fixed Gain Detector Chapter 3: Setup
Rev J, September 28, 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
PDA10A(-EC).
3. Plug the power supply into a 50 to 60 Hz, 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 PDA10A(-EC).
5. Power the PDA10A(-EC) on using the power switch located on the top
side of the unit.
Caution!
The PDA10A(-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 PDA10A(-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 Fixed Gain Detector
Page 4 13054-D02
Chapter 4 Operation
4.1. Theory of Operation
Thorlabs PDA series are ideal for measuring both pulsed and CW light sources.
The PDA10A(-EC) includes a reverse-biased PIN photo diode, mated to a fixed
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 Fixed Gain Detector Chapter 4: Operation
Rev J, September 28, 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.
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
1Approximate values, actual wavelength values will vary from unit to unit.

Si Amplified Fixed Gain Detector
Page 6 13054-D02
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 PDA10A(-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 PDA10A(-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:
 



󰇛󰇜∗∗∗󰇛󰇜

Si Amplified Fixed Gain Detector Chapter 5: Troubleshooting
Rev J, September 28, 2017 Page 7
Chapter 5 Troubleshooting
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
Specifications table.
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 Fixed Gain Detector
Page 8 13054-D02
Chapter 6 Specifications
All performance specifications are typical, performed at 25 °C ambient
temperature, and assume a 50 load, unless stated otherwise.
Electrical Specifications
Detector - Si PIN
Active Area - Ø1 mm (0.8 mm2)
Wavelength Range2200 to 1100 nm
Peak Wavelength p 730 nm (Typ)
Peak Response ( p) 0.44 A/W (Typ)
Small Signal Bandwidth - 150 MHz
NEP (λp) W/Hz 3.5 x 10-11
Noise (RMS) - 1.5 mVrms
Max Ouput Current IOUT 100 mA
Dark Offset - ±10 mV
Load Impedance - 50 to Hi-Z
Transimpedance Gain - 5 x 103V/A (50 )
1 x 104V/A (Hi-Z)
Output Voltage VOUT 0 to 5 V (50 )
0 to 10 V (Hi-Z)
General
On/Off Switch Slide
Output BNC (DC Coupled)
Package Size 2.80" x 1.90" x 0.83"
(70 mm x 48 mm x 21 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 50 °C
Storage Temp -25 to 70 °C
AC Power Supply AC – DC Converter
Input Power3
31 W
100 – 200 VAC (50 to 60Hz)
220 – 240 VAC (50 to 60 Hz)
2When long-term UV light is applied, the product specifications may degrade. For example,
the product’s UV response may decrease and the dark current may increase. The degree
to which the specifications may degrade is based upon factors such as the irradiation
level, intensity, and usage time.
3Although the power supply is rated for 31 W the PDA10A actual usage is <5 W over the
full operating range.