THORLABS PDA10D User manual

PDA10D(-EC)
Extended InGaAs
Amplified Detector
User Guide

InGaAs Amplified 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

InGaAs Amplified Detector Chapter 1: Warning Symbol Definitions
Rev G, December 19, 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

InGaAs Amplified Detector Chapter 2: Description
Page 2 13127-D01
Chapter 2 Description
The PDA10D(-EC) is an amplified, InGaAs detector designed for detection of light
ranging from 800 to 2600 nm. A buffered output drives 50 load impedances up
to 5 V. The PDA10D(-EC) housing includes a removable threaded coupler
(SM1T1) and retaining 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.

InGaAs Amplified Detector Chapter 3: Setup
Rev G, December 19, 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
PDA10D(-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 PDA10D(-EC).
5. Power the PDA10D(-EC) on using the power switch located on the top
side of the unit.
Caution!
The PDA10D(-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 PDA10D(-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.
!!

InGaAs Amplified Detector Chapter 4: Operation
Page 4 13127-D01
Chapter 4 Operation
4.1. Theory of Operation
Thorlabs PDA series are ideal for measuring both pulsed and CW light sources.
The PDA10D(-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

InGaAs Amplified Detector Chapter 4: Operation
Rev G, December 19, 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:
1Approximate values, actual wavelength values will vary from unit to unit

InGaAs Amplified Detector Chapter 4: Operation
Page 6 13127-D01
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 PDA10D(-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 PDA10D(-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:
 



󰇛󰇜∗∗∗󰇛󰇜

InGaAs Amplified Detector Chapter 5: Troubleshooting
Rev G, December 19, 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.

InGaAs Amplified Detector Chapter 6: Specifications
Page 8 13127-D01
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 - InGaAs
Active Area - Ø1.0 mm (0.8 mm2)
Wavelength Range 800 to 2600 nm
Peak Wavelength p 2300 nm (Typ.)
Peak Response ( p) 1.35 A/W (Typ.)
Small Signal Bandwidth - 15 MHz
NEP (λp) W/Hz 3.5 x 10-11
Noise (RMS) - 1.5 mVrms
Max Ouput Current IOUT 100 mA
Dark Offset - ±75 mV (Typ.)
±375 mV (Max)
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 Retaining Ring
Operating Temp 10 to 50 °C
Storage Temp -25 to 70 °C
AC Power Supply AC – DC Converter
Input Power2
31 W
100 – 200 VAC (50 to 60 Hz)
220 – 240 VAC (50 to 60 Hz)
2Although the power supply is rated for 31 W the PDA10D actual usage is <5 W over the
full operating range.