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Si Transimpedance Amplified Photodetectors

  • Si Transimpedance Amplified Detector
  • Fixed Switchable Amplified Detectors with
    Output up to 10 V
  • Wavelength Range From 200 - 1100 nm





Detector with Ø1" Lens
Tube Attached to a 30 mm
Cage System

Power Supply Included with Detector

Related Items

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photo detector power supply
Click to Enlarge

The power supply is included with all of the detectors on this page and replacements are sold below.
Removable Internal SM1 Adapter
Click to Enlarge

Each detector has an internal SM05 and external SM1 thread and comes with an
attached SM1T1 Internal SM1 Adapter
and SM1RR Retaining Ring.


  • Five Models Cover the 200 to 1100 nm Wavelength Range
  • Low-Noise, Wide Band Amplifiers
  • Fixed and Switchable Gain Modules
  • PDF10A Sensitive Down to Femtowatt Powers
  • 0 to 10 V Output
  • Compatible with SM1-Threaded and Some SM05-Threaded Products
  • Linear Power Supply Included

Thorlabs' Si Transimpedance Amplified Photodetectors, which consist of a photodiode and amplifier in a compact, low-profile package, are sensitive to light in the UV to NIR spectral region from 200 nm to 1100 nm. The slim profile housing enables use in light paths with space constraints. All connections and controls are located perpendicular to the light path, providing increased accessibility. Amplification is provided by low-noise transimpedance or voltage amplifiers that are capable of driving 50 Ω loads. Signal output is via a BNC connector. These photodetectors are ideal for use with Thorlabs' passive low-pass filters; these filters have a 50 Ω input and a high-impedance output that allows them to be directly attached to high-impedance measurement devices such as an oscilloscope. Thorlabs offers a wide variety of BNC, BNC-to-SMA, and SMC cables, as well as a variety of BNC, SMA, and SMC adapters.

Each housing provides two 8-32 tapped holes (M4 for -EC models) centered on the detector surface for vertical or horizontal post mounting. The housings also feature external SM1 (1.035"-40) threading and internal SM05 (0.535"-40) threading that are compatible with most Thorlabs SM1 and SM05 accessories. Additionally, an internally threaded SM1 coupler is included with each detector. This allows convenient mounting of SM1-compatible accessories, optics, and cage assembly accessories. The internal SM05 threading is only suitable for mating to an externally threaded SM05 lens tube (components such as fiber adapters cannot be threaded onto the SM05 threading). Most SM1-threaded fiber adapters are compatible with these detectors. However, the S120-FC internally SM1-threaded fiber adapter is not compatible with these detectors. Externally SM1-threaded adapters should be mated to the included internally SM1-threaded adapter, while internally SM1-threaded adapters can be mated directly to the housing.

A ±12 VDC power supply is included with each photodetector. The power supply features a switch, supporting either 115 or 230 VAC input voltage. Due to limitations in the IC, the high-speed amplifier used in these devices may become unstable, exhibiting oscillations or negative output if the linear power supply voltage is applied when the module is on. The unit should always be powered up using the power switch on the power supply or the unit itself. Hot plugging the unit is not recommended. Additionally, inhomogeneities at the edges of the active area of the detector can generate unwanted capacitance and resistance effects that distort the time-domain response of the photodetector output. Thorlabs therefore recommends that the incident light on the photodetector is well centered on the active area. The SM1 threading on the housing is ideally suited for mounting a Ø1" focusing lens or pinhole in front of the detector element.

Performance Specifications

Item # Detector
Active Area Wavelength Peak
Bandwidth Noise Equivalent Power
Rise Time
PDA10A Si 0.8 mm2
(Ø1.0 mm)
200 - 1100 nm 0.44 A/W
@ 750 nm
DC - 150 MHz 3.5 x 10-11 W/Hz1/2 2.3 ns b
PDA8A 0.5 mm2
(Ø0.8 mm)
320 - 1000 nm 0.56 A/W
@ 820 nm
DC - 50 MHz 6.5 x 10-12 W/Hz1/2 7 ns b
PDA36A 13 mm2
(3.6 x 3.6 mm)
350 - 1100 nm 0.65 A/W
@ 970 nm
DC - 10 MHz 5.93 x 10-13 - 2.91 x 10-11 W/Hz1/2 N/A c
PDA100A 100 mm2
(10 x 10 mm)
320 - 1100 nm 0.62 A/W
@ 960 nm
DC - 2.4 MHz 9.73 x 10-13 - 2.7 x 10-11 W/Hz1/2 N/A c
PDF10A 1.2 mm2
(1.1 x 1.1 mm)
320 - 1100 nm 0.6 A/W
@ 960 nm
DC - 20 Hz 1.4 x 10-15 W/Hz1/2 22 ms b
  • An NEP range is given for the switchable gain detectors, a max NEP is given for the fixed gain detectors.
  • Please note that rise time is specified at the peak responsivity wavelength.
  • Rise times depend on the chosen gain level and wavelength. As one increases the gain of a given optical amplifier, the bandwidth is reduced, and hence, the rise time increases. Please refer to the photodiode tutorial for information on calculating the rise time. Bandwidth specifications for each switchable photodetector may be found in the table below.

Gain Specifications

Item # Gain Type Gain w/ Hi-Z Load Gain w/ 50 Ω Load Output Voltage
w/ Hi-Z Load
Output Voltage
w/ 50 Ω Load
PDA10A Fixed 10 kV/A 5 kV/A 0 - 10 V 0 - 5 V
PDA8A Fixed 100 kV/A 50 kV/A 0 - 3.6 V 0 - 1.8 V

Item # Gain Step
w/ Hi-Z Loada
w/ 50 Ω Loada
Bandwidth Noise
NEPb Offset Output Voltage
w/ Hi-Z Load
Output Voltage
w/ 50 Ω Load
PDA36A 0 1.51 kV/A 0.75 kV/A 10.0 MHz 300 µV 2.91 x 10-11 W/Hz1/2 3 mV (10 mV Max) 0 - 10 V 0 - 5 V
10 4.75 kV/A 2.38 kV/A 5.5 MHz 280 µV 7.52 x 10-12 W/Hz1/2 4 mV (10 mV Max)
20 15 kV/A 7.5 kV/A 1.0 MHz 250 µV 2.34 x 10-12 W/Hz1/2 4 mV (10 mV Max)
30 47.5 kV/A 23.8 kV/A 260 kHz 260 µV 1.21 x 10-12 W/Hz1/2 4 mV (10 mV Max)
40 150 kV/A 75 kV/A 150 kHz 340 µV 5.93 x 10-13 W/Hz1/2 4 mV (10 mV Max)
50 475 kV/A 238 kV/A 45 kHz 400 µV 7.94 x 10-13 W/Hz1/2 4 mV (10 mV Max)
60 1.5 MV/A 750 kV/A 11 kHz 800 µV 1.43 x 10-12 W/Hz1/2 5 mV (10 mV Max)
70 4.75 MV/A 2.38 MV/A 5 kHz 1.10 mV 2.10 x 10-12 W/Hz1/2 6 mV (10 mV Max)
PDA100A 0 1.51 kV/A 0.75 kV/A 2.4 MHz 254 µV 2.7 x 10-11 W/Hz1/2 5 mV (10 mV Max) 0 - 10 V 0 - 5 V
10 4.75 kV/A 2.38 kV/A 1.6 MHz 261 µV 1.1 x 10-11 W/Hz1/2 6 mV (12 mV Max)
20 15 kV/A 7.5 kV/A 860 kHz 349 µV 8.91 x 10-12 W/Hz1/2 6 mV (15 mV Max)
30 47.5 kV/A 23.8 kV/A 480 kHz 561 µV 4.65 x 10-12 W/Hz1/2 8 mV (15 mV Max)
40 150 kV/A 75 kV/A 225 kHz 799 µV 3.55 x 10-12 W/Hz1/2 8 mV (15 mV Max)
50 475 kV/A 238 kV/A 78 kHz 998 µV 2.42 x 10-12 W/Hz1/2 8 mV (15 mV Max)
60 1.5 MV/A 750 kV/A 20 kHz 1163 µV 1.22 x 10-12 W/Hz1/2 8 mV (15 mV Max)
70 4.75 MV/A 2.38 MV/A 5.9 kHz 1490 µV 9.73 x 10-13 W/Hz1/2 ± 30 mV
  • Gain figures can also be expressed in units of Ω.
  • The Noise Equivalent Power is specified at the peak wavelength.
PDA Series Compact Design
PDA Series Design

Compact PDA & PDF Series Design

Thorlabs' Amplified Photodiode series features a slim design, which allows the detector access to the light path even between closely spaced optical elements.

The power supply input and the BNC output are located on the same outer edge of the package, further reducing the device thickness and allowing easier integration into tight optic arrangements. The PDA and PDF series detectors can fit into spaces as thin as 0.83" (21.1 mm) when the SM1 coupler is removed. With the SM1 coupler attached, the smallest width the detector can fit into is 1.03" (26.2 mm).

Additionally, the detectors have two tapped mounting holes perpendicular to each other so that the unit can be mounted in a horizontal or vertical orientation. This dual mounting feature offsets the fact that the cables protrude out the side of the package, thus requiring more free space above or alongside your beam path.

The switchable gain detectors feature an eight-position rotary gain switch (pictured below right) mounted on an outside edge perpendicular to the power supply and BNC output connections. The location of the gain switch allows for easy adjustments while the detector is mounted.

PDA detector Bottom and Side view

PDA Series Mounting Options

The PDA series of amplified photodetectors are compatible with our entire line of lens tubes, TR series posts, and cage mounting systems. Because of the wide range of mounting options, the best method for mounting the housing in a given optical setup is not always obvious. The pictures and text in this tab will discuss some of the common mounting solutions. As always, our technical support staff is available for individual consultation.

amplified photodetector amplified photodetector disassembled amplified photodetector close up
Picture of a PDA series photodetector as it will look when unpackaged. Picture of a DET series photodetector with the included SM1T1 and its retaining ring removed from the front of the housing. Thorlabs' PDA series photodetectors feature the same mounting options. A close up picture of the front of the PDA10A photodetector. The internal SM1 threading on the SM1T1 adapter and internal SM05 threading on the photodetector housing can be seen in this image.

TR Series Post (Ø1/2" Posts) System

The PDA housing can be mounted vertically or horizontally on a TR Series Post using the 8-32 (M4) threaded holes.

mounted amplified photodetector vertical mounted amplified photodetector horizontal
DET series photodetector mounted vertically on a TR series post. In this configuration, the output and power cables (PDA series) are oriented vertically and away from the optic table, facilitating a neater optical setup. PDA series photodetector mounted horizontally on a TR series post. In this configuration, the on/off switch is conveniently oriented on the top of the detector.

Lens Tube System

Each PDA housing includes a detachable Ø1" Optic Mount (SM1T1) that allows for Ø1" (Ø25.4 mm) optical components, such as optical filters and lenses, to be mounted along the axis perpendicular to the center of the photosensitive region. The maximum thickness of an optic that can be mounted in the SM1T1 is 0.1" (2.8 mm). For thicker Ø1" (Ø25.4 mm) optics or for any thickness of Ø0.5" (Ø12.7 mm) optics, remove the SM1T1 from the front of the detector and place (must be purchased separately) an SM1 or SM05 series lens tube, respectively, on the front of the detector.

The SM1 and SM05 threadings on the PDA photodetector housing make it compatible with our SM lens tube system and accessories. Two particularly useful accessories include the SM-threaded irises and the SM-compatible IR and visible alignment tools. Also available are fiber optic adapters for use with connectorized fibers.

Lens tube mounted amplified photodetector
DET series photodetector mounted onto an SM1L30C Ø1" Slotted Lens Tube, which is housing a focusing optic. The lens tube is attached to a 30 mm cage system via a CP02 SM1-Threaded 30 mm Cage Plate. This arrangement allows easy access for optic adjustment and signal alignment.

Cage System

The simplest method for attaching the PDA photodetector housing to a cage plate is to remove the SM1T1 that is attached to the front of the PDA when it is shipped. This will expose external SM1 threading that is deep enough to thread the photodetector directly to a CP02 30 mm cage plate. When the CP02 cage plate is tightened down onto the PDA photodetector housing, the cage plate will not necessarily be square with the detector. To fix this, back off the cage plate until it is square with the photodetector and then use the retaining ring included with the SM1T1 to lock the PDA photodetector into the desired location.

This method for attaching the PDA photodetector housing to a cage plate does not allow much freedom in determining the orientation of the photodetector; however, it has the benefit of not needing an adapter piece, and it allows the diode to be as close as possible to the cage plate, which can be important in setups where the light is divergent. As a side note, Thorlabs sells the SM05PD and SM1PD series of photodiodes that can be threaded into a cage plate so that the diode is flush with the front surface of the cage plate; however, the photodiode is unbiased.

For more freedom in choosing the orientation of the PDA photodetector housing when attaching it, a SM1T2 lens tube coupler can be purchased. In this configuration the SM1T1 is left on the detector and the SM1T2 is threaded into it. The exposed external SM1 threading is now deep enough to secure the detector to a CP02 cage plate in any orientation and lock it into place using one of the two locking rings on the ST1T2.

photodetector with cage plate

photodetector with cage plate

photodetector with cage plate and spacer

This picture shows a DET series photodetector attached to a CP02 cage plate after removing the SM1T1. The retaining ring from the SM1T1 was used to make the orientation of the detector square with the cage plate. These two pictures show a DET series photodetector in a horizontal configuration. The top picture shows the detector directly coupled to a CP02 cage plate.
The bottom picture shows a DET series photodetector attached to a CP02 cage plate using an SM1T2 adapter in addition to the SM1T1 that comes with the PDA series detector.

Although not pictured here, the PDA photodetector housing can be connected to a 16 mm cage system by purchasing an SM05T2. It can be used to connect the PDA photodetector housing to an SP02 cage plate.


The image below shows a Michelson Interferometer built entirely from parts available from Thorlabs. This application demonstrates the ease with which an optical system can be constructed using our lens tube, TR series post, and cage systems. A PDA series photodetector is interchangeable with the DET series photodetector shown in the picture.

Michelson interferometer

The table below contains a part list for the Michelson Interferometer for use in the visible range. Follow the links to the pages for more information about the individual parts. 

Item # Quantity Description Item # Quantity Description
KC1 1 Mirror Mount CT1 1 1/2" Travel Translator
BB1-E02 2 Broadband Dielectric Laser Mirrors SM1D12 1 SM1 Threaded Lens Tube Iris
ER4 8 4" Cage Rods SM1L30C 1 SM1 3" Slotted Lens Tube
ER6 4 6" Cage Rods SM1V05 1 Ø1" Adjustable Length Lens Tube
CCM1-BS013 1 Cube-Mounted Beamsplitter CP08FP 1 30 mm Cage Plate for FiberPorts
BA2 1 Post Base (not shown in picture) PAF-X-5-A 1 FiberPort
TR2 1 Ø1/2" Post, 2" in Length P1-460B-FC-2 1 Single Mode Fiber Patch Cable
PH2 1 Ø1/2" Post Holder DET36A / PDA36A 1 Biased / Amplified Photodiode Detector

BNC Female Output (Photodetector)

BNC Female

0 - 10 V Output

PDA Male (Power Cables)

Pinout for PDA Power Cable

PDA Female (Photodetector)

Pinout for PDA Power Connector

Photodiode Tutorial

Theory of Operation

A junction photodiode is an intrinsic device that behaves similarly to an ordinary signal diode, but it generates a photocurrent when light is absorbed in the depleted region of the junction semiconductor. A photodiode is a fast, highly linear device that exhibits high quantum efficiency based upon the application and may be used in a variety of different applications.

It is necessary to be able to correctly determine the level of the output current to expect and the responsivity based upon the incident light. Depicted in Figure 1 is a junction photodiode model with basic discrete components to help visualize the main characteristics and gain a better understanding of the operation of Thorlabs' photodiodes.

Equation 1
Photodiode Circuit Diagram
Figure 1: Photodiode Model

Photodiode Terminology

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:

Equation 2

Modes of Operation (Photoconductive vs. Photovoltaic)
A photodiode can be operated in one of two modes: photoconductive (reverse bias) or photovoltaic (zero-bias). Mode selection depends upon the application's speed requirements and the amount of tolerable dark current (leakage current).

In photoconductive mode, an external reverse bias is applied, which is the basis for our DET series detectors. The current measured through the circuit indicates illumination of the device; the measured output current is linearly proportional to the input optical power. Applying a reverse bias increases the width of the depletion junction producing an increased responsivity with a decrease in junction capacitance and produces a very linear response. Operating under these conditions does tend to produce a larger dark current, but this can be limited based upon the photodiode material. (Note: Our DET detectors are reverse biased and cannot be operated under a forward bias.)

In photovoltaic mode the photodiode is zero biased. The flow of current out of the device is restricted and a voltage builds up. This mode of operation exploits the photovoltaic effect, which is the basis for solar cells. The amount of dark current is kept at a minimum when operating in photovoltaic mode.

Dark Current
Dark current is leakage current that flows when a bias voltage is applied to a photodiode. When operating in a photoconductive mode, there tends to be a higher dark current that varies directly with temperature. Dark current approximately doubles for every 10 °C increase in temperature, and shunt resistance tends to double for every 6 °C rise. Of course, applying a higher bias will decrease the junction capacitance but will increase the amount of dark current present.

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.

MaterialDark CurrentSpeedSpectral RangeCost
Silicon (Si) Low High Speed Visible to NIR Low
Germanium (Ge) High Low Speed NIR Low
Gallium Phosphide (GaP) Low High Speed UV to Visible Moderate
Indium Gallium Arsenide (InGaAs) Low High Speed NIR Moderate
Indium Arsenide Antimonide (InAsSb) High Low Speed NIR to MIR High
Extended Range Indium Gallium Arsenide (InGaAs) High High Speed NIR High
Mercury Cadmium Telluride (MCT, HgCdTe) High Low Speed NIR to MIR High

Junction Capacitance
Junction capacitance (Cj) is an important property of a photodiode as this can have a profound impact on the photodiode's bandwidth and response. It should be noted that larger diode areas encompass a greater junction volume with increased charge capacity. In a reverse bias application, the depletion width of the junction is increased, thus effectively reducing the junction capacitance and increasing the response speed.

Bandwidth and Response
A load resistor will react with the photodetector junction capacitance to limit the bandwidth. For best frequency response, a 50 Ω terminator should be used in conjunction with a 50 Ω coaxial cable. The bandwidth (fBW) and the rise time response (tr) can be approximated using the junction capacitance (Cj) and the load resistance (RLOAD):

Equation 3

Noise Equivalent Power
The noise equivalent power (NEP) is the generated RMS signal voltage generated when the signal to noise ratio is equal to one. This is useful, as the NEP determines the ability of the detector to detect low level light. In general, the NEP increases with the active area of the detector and is given by the following equation:

Photoconductor NEP

Here, S/N is the Signal to Noise Ratio, Δf is the Noise Bandwidth, and Incident Energy has units of W/cm2. For more information on NEP, please see Thorlabs' Noise Equivalent Power White Paper.

Terminating Resistance
A load resistance is used to convert the generated photocurrent into a voltage (VOUT) for viewing on an oscilloscope:

Equation 4

Depending on the type of the photodiode, load resistance can affect the response speed. For maximum bandwidth, we recommend using a 50 Ω coaxial cable with a 50 Ω 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.

Shunt Resistance
Shunt resistance represents the resistance of the zero-biased photodiode junction. An ideal photodiode will have an infinite shunt resistance, but actual values may range from the order of ten Ω to thousands of MΩ and is dependent on the photodiode material. For example, and InGaAs detector has a shunt resistance on the order of 10 MΩ while a Ge detector is in the kΩ range. This can significantly impact the noise current on the photodiode. For most applications, however, the high resistance produces little effect and can be ignored.

Series Resistance
Series resistance is the resistance of the semiconductor material, and this low resistance can generally be ignored. The series resistance arises from the contacts and the wire bonds of the photodiode and is used to mainly determine the linearity of the photodiode under zero bias conditions.

Common Operating Circuits

Reverse Biased DET Circuit
Figure 2: Reverse-Biased Circuit (DET Series Detectors)

The DET series detectors are modeled with the circuit depicted above. The detector is reverse biased to produce a linear response to the applied input light. The amount of photocurrent generated is based upon the incident light and wavelength and can be viewed on an oscilloscope by attaching a load resistance on the output. The function of the RC filter is to filter any high-frequency noise from the input supply that may contribute to a noisy output.

Reverse Biased DET Circuit
Figure 3: Amplified Detector Circuit

One can also use a photodetector with an amplifier for the purpose of achieving high gain. The user can choose whether to operate in Photovoltaic of Photoconductive modes. There are a few benefits of choosing this active circuit:

  • Photovoltaic mode: The circuit is held at zero volts across the photodiode, since point A is held at the same potential as point B by the operational amplifier. This eliminates the possibility of dark current.
  • Photoconductive mode: The photodiode is reversed biased, thus improving the bandwidth while lowering the junction capacitance. The gain of the detector is dependent on the feedback element (Rf). The bandwidth of the detector can be calculated using the following:

Equation 5

where GBP is the amplifier gain bandwidth product and CD is the sum of the junction capacitance and amplifier capacitance.

Effects of Chopping Frequency

The photoconductor signal will remain constant up to the time constant response limit. Many detectors, including PbS, PbSe, HgCdTe (MCT), and InAsSb, have a typical 1/f noise spectrum (i.e., the noise decreases as chopping frequency increases), which has a profound impact on the time constant at lower frequencies.

The detector will exhibit lower responsivity at lower chopping frequencies. Frequency response and detectivity are maximized for

Photoconductor Chopper Equation

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Posted Comments:
Posted Date:2017-01-18 09:19:54.95
Hi, We have a PDA10A in our laboratory in Belgium and we measure strange values. In the data sheet, it is mentioned that the output voltage of the photodiode is in the range 0V->10V. However, if we connect the output of the PDA10 directly to an oscilloscope, we measure values of -180mV when there is almost no light. Can you help us out with this problem? Best regards, Jona Beysens
Posted Date:2017-01-19 02:51:04.0
Hello Jona, thank you for contacting Thorlabs. I will reach out to you directly to troubleshoot your PDA10A.
Posted Date:2016-12-01 11:09:02.007
Your tutorial indicates that these Si photodetectors are highly linear. Can you quantify the linearity and dynamic range? i.e. how linear and over what range?
Posted Date:2016-12-07 03:05:17.0
This is a response from Sebastian at Thorlabs. Thank you very much for your inquiry. The maximum output voltage swing of PDF10A is +10V. Saturation of the output will occur at optical input power greater than CW Saturation Power (16pW for PDF10A). Saturation of the Photodiode will cause nonlinear behavior. ND filters can be used to reduce the optical power and extend the operation range. The minimal detectable power, calculated from NEP at 960nm and SNR=1 , is 6fW. I have contacted you directly to provide further assistance.
Posted Date:2016-07-18 09:31:07.223
Hello, I'm using the PDA36A-EC to detect light pulses from 1 to 10 µs. I observe a charging time of 1.8 µs for the photodetector response signal and I was wondering if it was a normal value. If not can it come from the photodetector? Thank you.
Posted Date:2016-07-18 10:52:36.0
Response from Jeremy at Thorlabs: The rise time is going to be dependent on the gain setting that you choose. Also, if the detector is saturated, the rise time will be longer than usual as well. We will contact you directly to troubleshoot this.
Posted Date:2016-06-13 20:05:32.29
Hello,I have a PDA36A Si detector which does not work now. I wonder how to repair it? Should I just send it back to Thorlabs? I think it is under warranty but not very sure.
Posted Date:2016-06-15 10:52:17.0
Response from Bweh at Thorlabs USA: I have contacted you directly.
Posted Date:2016-03-25 15:53:47.357
What is the maximum amount of optical power that the PDA36A and PDA100A can withstand before the damage occurs (not saturation).
Posted Date:2016-03-25 05:01:36.0
Response from Bweh at Thorlabs USA: You should keep the power below 100mW to prevent damage. For typical use, under 1mW is recommended to keep the detector in the linear regime as these are amplified detectors.
Posted Date:2015-03-31 16:39:31.477
I want to use PDA10A for detection of rapid fluorescence signals (60MHz)from organic dyes in cell membranes. this PDA10A can go to work?
Posted Date:2015-03-31 01:17:33.0
Response from Jeremy at Thorlabs: We will have to get more information about your application before being able to recommend a specific detector. I will contact you directly about this.
Posted Date:2014-10-16 15:17:43.007
Hello, I want to ask about the output of the PDA10A detector. What is the compatible power meter? Please contact me via email. Thank you.
Posted Date:2014-10-16 02:35:46.0
Response from Jeremy at Thorlabs: The PDA10A outputs a voltage signal but the detector's response is not NIST calibrated. We do offer power meter system which can be found at I will contact you directly about our power meter system.
Posted Date:2014-10-08 09:36:17.2
Is there any certification that the responsivity is linear across intensity range? i.e. is dV/dP the same for output in the 0-1V range as the 9-10?
Posted Date:2014-10-08 04:04:38.0
Response from Jeremy at Thorlabs: The response of the detector is linear for output below the maximum voltage (10V with Hi-Z load).
Posted Date:2014-08-22 18:28:19.383
hello, I cannot obtain more than 0,45V output from my PDA8A. Under this value detector works good, but at 0,45V looks like it is saturated. What can be wrong? Thanks
Posted Date:2014-08-26 07:38:27.0
This is a response from Stefan at Thorlabs. Thank you very much for your inquiry. I am sorry that you face problems with the PDA8A. I will contact you directly to troubleshoot this problem.
Posted Date:2014-07-18 12:44:03.447
Dear Sirs, We would want to use one of your Amplified Photodetectors for detecting radiation of N2-laser. Beam characteristics: LengthxWidth-20x10mm, Pulse intensity-0,5 mJ, pulse duration-100ns. What Amp. Photodetector is best for our application? As I understand we'd need additional focusing and filtering components for this system... What can You advise?
Posted Date:2014-08-01 01:49:35.0
Response from Jeremy at Thorlabs: There are a few details missing from your setup description. We will contact you directly to discuss about this.
Posted Date:2014-03-28 17:31:22.757
The datasheet for the PDA8A/M specifies the output voltage for terminations of Hi-Z and 50 Ohm. I have an application where I'd like to connect the detector to a Mini-circuits mixer (tuf-3lh) which has an input impedance given by a coil connected to ground such that at DC the impedance is 0 Ohm. This will of course force the signal to 0 at DC. Will this damage the PDA8A/M detector by drawing to much current. What is the output impedance of the PDA8A/M and how is it connected, in series or in parallel? Regards, Hans Harhoff Andersen.
Posted Date:2014-04-14 05:01:57.0
A response from Julien at Thorlabs: Thank you for your inquiry! The connection to the coil will not damage the detector. This being said, one could of course use a coupling capacitance before the balun to achieve separation from the DC path. The output impedance is 47Ohms series.
Posted Date:2013-09-06 17:49:33.61
I'm having a hard time reproducing the numbers in the manual of the PDA36A for the NEP. I would have assumed that NEP = Noise_rms / Sqrt(BW) / Gain / Responsivity, but when I put in these numbers I get a NEP more than an order magnitude higher. Am I doing something incorrectly?
Posted Date:2013-09-11 14:38:00.0
Response from Jeremy at Thorlabs: You are correct that NEP = Vrms/(Gain*Responsivity*vbandwidth). The bandwidth used in the calculation is the bandwidth of the measuring system and not the bandwidth of the detector.
Posted Date:2013-08-28 14:19:19.92
There is a response curve in the Manual of PDA10A,but I can't find the detail spectrum response data, the responsivity of each wavelength. Would you please give me this?
Posted Date:2013-08-29 16:35:00.0
Response from Sean at Thorlabs: Thank you for your feedback. I emailed you the data file directly, and we are in the process of adding the data for all of our Amplified Detectors directly to the website.
Posted Date:2013-05-09 13:33:28.323
I am planing on using this PDA for detection of rapid (msec) fluorescence signals from organic dyes in cell membranes but I am not sure that about the sensitivity. Do you have any experience with this type of measurement (voltage clamp fluorometry) or can recommend references?
Posted Date:2013-05-09 15:00:00.0
Response from Jeremy at Thorlabs: I will get in contact with you directly do discuss about the details in your experiments.
Posted Date:2013-04-05 12:09:53.973
I have a question about PDA36A. I plan to do photoluminescence experiment with it under low temperature (>77K). Does PDA36A work at that range? Do you have a responsitivity curve for that?
Posted Date:2013-04-08 09:52:00.0
Response from Jeremy at Thorlabs: The operating temperature for the PDA36A is 0-40°C.
Posted Date:2013-03-27 05:19:04.92
Why the maximum incident light intensity is not indicated clearly, please?
Posted Date:2013-04-02 16:04:00.0
Response from Chris at Thorlabs: Thank you for using our web feedback. The saturation point can be found by dividing the max voltage output for it's corresponding gain and responsivity. So for example with a 50Ohm resistance, the PDA8A can ouput up to 5V, dividing by 50kV/A and 0.5A/W (at peak responsivity), we end up with 64.3mW on the lowest gain setting. The same can be done for the other detectors as well. Each on the lowest settings, the PDA10A would be 2.22mW. The PDFF10A would be 2nW, the PDA36A and PDA100A would both be 10.3mW.
Posted Date:2013-03-15 09:07:24.04
I have a DC sensing application where i use 4 PDA36A detectors at the highest gain setting. When I turn off the light source, there is a wide range of dark level--understandable for different chips. But some are negative. I don't understand why there would be negative dark signal unless an offset is built into the output...can you explain?
Posted Date:2013-03-18 14:35:00.0
Response from Jeremy at Thorlabs: The negative value that you see is the amplifier offset, which can be negative (for PDA36A, the offset should be within ±10mV at 70dB gain). For the recently purchased PDA36A (after July 2012), and PDA100A (after October 2012), there is a way to adjust the amplifier offset. If you remove the back cover of the PDA, there is a trimmer potentiometer which sets the offset. You can set the offset to what your desire value by covering up, and then adjusting the offset at 70dB gain setting.
Posted Date:2012-12-06 15:58:00.0
Response from Sean at Thorlabs: Thank you for your feedback. For the PDA36A(-EC), the bandwidth at the 70 dB gain setting is 5 kHz. Complete specifications at each gain setting can be found on page 9 of the manual ( I have already updated the webpage to refer future customers to that location. We are in the process of developing a new website feature that will allow us to provide the complete set of specifications for detectors and other products in a more convinient way, and I will make sure that this page is one of the first to utilize the new feature.
Posted Date:2012-12-06 15:17:45.83
What is the bandwidth at full gain - it is not clear from the web site and I have an inkling that you reduce the bandwidth at higher gain. thanks Graham
Posted Date:2011-06-28 17:09:00.0
Response from Javier at Thorlabs to Veinardi.Suendo: Thank you very much for contacting us. Although it would be recommendable to place the FEL1200 filter at the input of the collimator, the structure of the setup you propose might work without the lens. The only concern is, of course, the space between the tip of the fiber and the lens. In principle, you could use the following path: Collimator-> Fiber-> SM1SMA Fiber Adapter-> Filter-> Detector. However, since the overall thickness of the filter is 6.3 mm, this added distance between the fiber and the active area of the detector, which is 1.1 mm x 1.1 mm, could cause some loss, since the output from the fiber will be divergent. You could perhaps use an aspheric lens pair to focus the output from the fiber onto the detector (link below), but this would add to the overall length and complexity of the setup. I will contact you directly to discuss this and other possibilities for your application. Aspheric lens pairs: SM1SMA adapter:
Posted Date:2011-06-28 15:59:21.0
Dear Sirs, We planned to purchase your product (PDF10C/M) for our lab. in Indonesia. I believed that they have already launched the project. However, we need your assistance to connect this detector to optical fiber with SMA termination and a long wave pass filter (FEL1200). Would you mind telling us, which part is needed. Personally, I have in my mind this kind of setup: (collimator)--> (Optical Fiber)--> (fiber adapter)--> (SM1 tube)--> (lens?)--> (filter)--> (detector). Is it possible? Do we really need a lens in this case? Thank you very much for your assistance. Yours Sincerely, Dr. Veinardi Suendo Customer Email: This customer would like to be contacted.
Posted Date:2011-04-20 09:11:00.0
Response from Javier at Thorlabs to last poster: Thank you very much for your feedback. We have updated the Overview tab in order to clarify the different transimpedance specs for these detectors. Please do not hesitate to contact us at if you have any further questions or comments.
Posted Date:2011-04-19 17:21:14.0
Transimpedance gain for the PDF10A is mentioned in the Overview tab, but the wording seems to indicate that both this and the PDF10C share a common gain value.

The following table lists Thorlabs' selection of photodiodes and photoconductive detectors. Item numbers in the same row contain the same detector element.

Photodetector Cross Reference
Wavelength Material Unmounted Photodiode Unmounted Photoconductor Mounted Photodiode Biased Detector Amplified Detector
150 - 550 nm GaP FGAP71 - SM05PD7A DET25K PDA25K
200 - 1100 nm Si FDS010 - SM05PD2A
Si - - SM1PD2A - -
320 - 1100 nm Si - - - - PDA8A
Si - - - - PDF10A
Si - - - - PDA100A
340 - 1100 nm Si FDS10X10 - - - -
350 - 1100 nm Si FDS100
FDS100-CAL a
- SM05PD1A
Si FDS1010
FDS1010-CAL a
400 - 1100 nm Si FDS025 b
FDS02 c
- - DET02AFC
400 - 1700 nm Si & InGaAs DSD2 - - - -
500 - 1700 nm InGaAs - - DET10N - -
800 - 1700 nm InGaAs FGA21
- SM05PD5A - PDA20C
InGaAs FGA01 b
- - DET01CFC -
InGaAs FDGA05 - - - PDA10CF
InGaAs - - - DET08CFC
InGaAs - - - DET20C -
800 - 1800 nm Ge FDG03
Ge FDG50 - - DET50B PDA50B
Ge FDG05 - - - -
800 - 2600 µm InGaAs FD05D - - DET05D -
FD10D - - DET10D -
900 - 1700 nm InGaAs FGA10 - SM05PD4A DET10C PDA10CS
1.0 - 2.9 µm PbS - FDPS3X3 - - PDA30G
1.0 - 5.8 µm InAsSb - - - - PDA10PT
1.2 - 2.6 µm InGaAs - - - - PDA10D
1.5 - 4.8 µm PbSe - FDPSE2X2 - - PDA20H
2.0 - 5.4 µm HgCdTe (MCT) - - - - PDA10JT
  • Calibrated Unmounted Photodiode
  • Unmounted TO-46 Can Photodiode
  • Unmounted TO-46 Can Photodiode with FC/PC Bulkhead

Si Transimpedance Amplified Photodetectors

Item # PDA10A PDA8A PDA36A PDA100Aa
Click Image to Enlargeb PDA10A PDA8A PDA36A PDA100A
Detector Element
(Click for Image)
Si Si Si Si
Wavelength Range 200 - 1100 nm 320 - 1000 nm 350 - 1100 nm 320 - 1100 nm
Responsivity Curve More Info More Info More Info More Info
Active Area 0.8 mm2
(Ø1.0 mm)
0.5 mm2
(Ø0.8 mm)
13 mm2
(3.6 mm x 3.6 mm)
100 mm2
(10 mm x 10 mm)
Gain Fixed: 10 kV/A with Hi-Z Load
5 kV/A with 50 Ω Load
Fixed: 100 kV/A with Hi-Z Load
50 kV/A with 50 Ω Load
8 x 10 dB Steps 8 x 10 dB Steps
Bandwidth Range DC - 150 MHz DC - 50 MHz DC - 10 MHz DC - 2.4 MHz
Noise-Equivalent Power (NEP) 3.5 x 10-11 W/Hz1/2 6.5 x 10-12 W/Hz1/2 5.93 x 10-13 - 2.91 x 10-11 W/Hz1/2 9.73 x 10-13 - 2.7 x 10-11 W/Hz1/2
  • The bandwidth and detection wavelength was improved in October 2012. PDA100A models purchased prior to that time will have a detection range of 400 - 1100 nm and a bandwidth of 1.5 MHz.
  • All photodetectors are shown with the included SM1T1 Internal SM1 Adapter attached.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available / Ships
PDA10A Support Documentation
PDA10ASi Fixed Gain Detector, 200-1100 nm, 150 MHz BW, 0.8 mm2, 8-32 Taps
PDA8A Support Documentation
PDA8ASi Fixed Gain Detector, 320-1000 nm, 50 MHz BW, 0.5 mm2, 8-32 Taps
PDA36A Support Documentation
PDA36ASi Switchable Gain Detector, 350-1100 nm, 10 MHz BW, 13 mm2, 8-32 Taps
PDA100A Support Documentation
PDA100ASi Switchable Gain Detector, 320-1100 nm, 2.4 MHz BW, 100 mm2, 8-32 Taps
+1 Qty Docs Part Number - Metric Price Available / Ships
PDA10A-EC Support Documentation
PDA10A-ECSi Fixed Gain Detector, 200-1100 nm, 150 MHz BW, 0.8 mm2, M4 Taps
PDA8A/M Support Documentation
PDA8A/MSi Fixed Gain Detector, 320-1000 nm, 50 MHz BW, 0.50 mm2, M4 Taps
PDA36A-EC Support Documentation
PDA36A-ECSi Switchable Gain Detector, 350-1100 nm, 10 MHz BW, 13 mm2, M4 Taps
PDA100A-EC Support Documentation
PDA100A-ECSi Switchable Gain Detector, 320-1100 nm, 2.4 MHz BW, 100 mm2, M4 Taps

Si Transimpedance Amplified Photodetector, Femtowatt Sensitivity

Item # PDF10A
Click Image to Enlargea PDF10A
Detector Element
(Click for Image)
Wavelength Range 320 - 1100 nm
Responsivity Curve More Info
Active Area 1.2 mm2
(1.1 mm x 1.1 mm)
Gain Fixed: 1 x 109 kV/A
Bandwidth Range DC - 20 Hz
Noise-Equivalent Power (NEP) 1.4 x 10-15 W/Hz1/2
  • The photodetector is shown with the included SM1T1 Internal SM1 Adapter attached.

Each PDF10A(/M) detector includes a TRE(/M) electrically isolated TR post adapter.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available / Ships
PDF10A Support Documentation
PDF10ASi Amplified Detector, 320-1100 nm, 20 Hz BW, 1.2 mm2, 8-32 Taps
+1 Qty Docs Part Number - Metric Price Available / Ships
PDF10A/M Support Documentation
PDF10A/MSi Amplified Detector, 320-1100 nm, 20 Hz BW, 1.2 mm2, M4 Taps

PDA Power Supply Cable

Pinout for Cable

The PDA-C-72 is a power cord for the PDA line of amplified photodetectors. The cord has tinned leads on one end and a PDA-compatible 3-pin connector on the other end. It can be used to power the PDA series of amplified photodetectors with any power supply that provides a DC voltage. The pin descriptions are shown to the right.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
PDA-C-72 Support Documentation
PDA-C-7272" PDA Power Supply Cable, 3-Pin Connector

12 VDC Regulated Power Supply

  • Replacement Power Supply for the Amplified Photodetectors Sold Above
  • ±12 VDC Power Output
  • Current Limit Enabling Short Circuit and Overload Protection
  • On/Off Switch with LED Indicator
  • Switchable AC Input Voltage (115 or 230 VAC)
  • 6.6 ft (2 m) Cable with LUMBERG RSMV3-657/2M Male Connector
  • UL and CE Compliant

The LDS1212 ±12 VDC Regulated Linear Power Supply is intended as a replacement for the supply that comes with our PDA line of amplified photodetectors sold on this page. The cord has three pins: one for ground, one for +12 V, and one for -12 V (see diagram above). This power supply ships with a location-specific power cord and the voltage switch is set to the proper setting for your location before it is shipped. This power supply can also be used with our PDB series of balanced photodetectors, our PMM series of photomultiplier modules, our APD series of avalanche photodetectors, and our dichroic atomic vapor spectroscopy systems.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
LDS1212 Support Documentation
LDS1212±12 VDC Regulated Linear Power Supply, 6 W, 115/230 VAC
Lead Time

Internally SM1-Threaded Fiber Adapters

These internally SM1-threaded (1.035"-40) adapters mate connectorized fiber to any of our externally SM1-threaded components, including our photodiode power sensors, our thermal power sensors, and our photodetectors. These adapters are compatible with the housing of the photodetectors on this page.

Item # S120-SMA S120-ST S120-SC S120-LC
Click Image to Enlarge S120-SMA S120-ST S120-SC S120-LC
Fiber Connector Typea SMA ST SC LC
Thread Internal SM1 (1.035"-40)
  • Other Connector Types Available upon Request
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
S120-SMA Support Documentation
S120-SMASMA Fiber Adapter Cap with Internal SM1 (1.035"-40) Thread
S120-ST Support Documentation
S120-STST/PC Fiber Adapter Cap with Internal SM1 (1.035"-40) Thread
S120-SC Support Documentation
S120-SCSC/PC Fiber Adapter Cap with Internal SM1 (1.035"-40) Thread
S120-LC Support Documentation
S120-LCLC/PC Fiber Adapter Cap with Internal SM1 (1.035"-40) Thread

Externally SM1-Threaded Fiber Adapters

Each disk has four dimples, two in the front surface and two in the back surface, that allow it to be tightened from either side with the SPW909 or SPW801 spanner wrench. The dimples do not go all the way through the disk so that the adapters can be used in light-tight applications when paired with SM1 lens tubes. Once the adapter is at the desired position, use an SM1RR retaining ring to secure it in place.

Adapter Image
(Click the Image to Enlarge)
Connector Type FC/PC FC/APC SMA ST/PC
Threading External SM1 (1.035"-40)
  • Please note that the SM1FCA has a mechanical angle of only 4°, even though the standard angle for these connectors is 8°. There is a 4° angle of deflection caused by the glass-air interface; when combined with the 4° mechanical angle, the output beam is aligned perpendicular to the adapter face.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
SM1FC Support Documentation
SM1FCFC/PC Fiber Adapter Plate with External SM1 (1.035"-40) Thread
3-5 Days
SM1FCA Support Documentation
SM1FCAFC/APC Fiber Adapter Plate with External SM1 (1.035"-40) Thread
3-5 Days
SM1SMA Support Documentation
SM1SMASMA Fiber Adapter Plate with External SM1 (1.035"-40) Thread
SM1ST Support Documentation
SM1STST/PC Fiber Adapter Plate with External SM1 (1.035"-40) Thread
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