Mounted Photodiodes

  • InGaAs, Silicon, or Ge Photodiodes
  • Ideal for Measuring Pulsed and CW Sources
  • Housing with External SM05 or SM1 Threading


FDS010 Photodiode Mounted in SM05 Externally Threaded Housing


FDS1010 Photodiode Mounted in SM1 Externally Threaded Housing

Related Items

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Mounted and Unmounted Detectors
Unmounted Photodiodes (200 - 2600 nm)
Calibrated Photodiodes (350 - 1800 nm)
Mounted Photodiodes (200 - 1800 nm)
Thermopile Detectors (0.2 - 15 µm)
Photovoltaic Detectors (2.0 - 10.6 µm)
Pigtailed Photodiodes (320 - 1000 nm)

Click to Enlarge

The PBM42 Bias Module Used to Apply an External Reverse Bias Voltage to the SM1PD2A Photodiode

Thorlabs offers photodiodes of Si, InGaAs, or Ge material mounted in convenient SM05 (0.535"-40) or SM1 (1.035"-40) externally threaded tubes. The electrical output of the photodiode is provided through a standard SMA connector (SM05PD Series) or BNC connector (SM1PD Series) for quick connection to the measuring circuit.

Click to Enlarge

PDA200C Benchtop Photodiode Amplifier Connected to
an SM1-Threaded Mounted Photodiode Using a BNC Cable

The mounted photodiodes presented here are compatible with the PDA200C Benchtop Photodiode Amplifier and Thorlabs' Modular Photodiode Amplifiers. The photodiodes come in either a Type A (cathode grounded) or Type B (anode grounded) arrangement. The pin codes for specific items may be found below. All models are ideal for measuring pulsed and CW sources. The insulated external thread on the main body makes these photodiodes compatible with all Thorlabs SM05 and SM1 Mounting Adapters.

Please refer to the tables below for more details on each model and note that these photodiodes are not calibrated. We also offer unmounted calibrated photodiodes.

Please note that 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 photodiode output. Thorlabs therefore recommends that the incident light on the photodiode is well centered on the active area. This can be accomplished by placing a focusing lens or pinhole in front of the detector element.

For applying an external bias voltage to these photodiodes, we offer the PBM42 bias module (sold below), which is compatible via adapters with all of the photodiodes on this page and is shown in the image to the right.

For information on the photodiode saturation limit and the noise floor, as well as a collection of Thorlabs-conducted experiments regarding spatial uniformity (or varying responsivity) and dark current as a function of temperature, refer to the Lab Facts tab. The Photodiode Tutorial provides more general information regarding the operation, terminology, and theory of photodiodes.

Thorlabs offers spectral-flattening filters that are designed to improve the response uniformity of our silicon photodiodes. Click here to learn more.

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 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.

Material Dark Current Speed Spectral Range Cost
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 input signal power that results in a signal-to-noise ratio (SNR) of 1 in a 1 Hz output bandwidth. 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

The images below show examples of electrical circuits that can be used in conjunction with our mounted diodes. Our mounted photodiodes with SM05-threaded (0.535"-40) housings utilize an SMA connector type whereas those with SM1-threaded (1.035"-40) housings have a BNC connector type. Figure 1 below depicts a cathode-grounded photodiode with an example circuit. This is a reverse bias configuration with a positive voltage output. Figure 2 depicts an anode-grounded photodiode with an example circuit. Note that in this instance, the polarity of the power source has been reversed. Figure 2 is also a reverse bias configuration but will have a negative voltage output.

The major difference between the configurations shown in Figures 1 and 2 is the range of the output voltage. Figure 1 will output 0 to +V volts, whereas Figure 2 will output -V to 0 volts. For more information on photodiode circuits, values, and theory please see the Photodiode Tutorial tab

SM05- and SM1-Threaded Mounted Photodiodes, Cathode Grounded

Cathode Ground, SMA Circuit
Figure 1

SM05- and SM1-Threaded Mounted Photodiodes, Anode Grounded

Anode Ground, SMA Circuit
Figure 2

This tab contains a collection of experiments performed at Thorlabs regarding the performance of photodiodes we offer. Each section is its own independent experiment, which can be viewed by clicking in the appropriate box below. Photodiode Saturation Limit and Noise Floor explores how different conditions, including temperature, resistivity, reverse-bias voltage, responsivity, and system bandwidth, can affect noise in a photodiode's output. Photodiode Spatial Uniformity explores variations in the responsivity as a small-diameter light beam is scanned across the active area of the photodiode. Photodiodes with different material compositions are tested, and eight units of one silicon-based model are tested to investigate unit-to-unit variations. Dark Current as a Function of Temperature and Noise Equivalent Power (NEP) as a Function of Temperature describe how dark current and NEP, respectively, vary with temperature and how measurements are affected. Beam Size and Photodiode Saturation shows how the photodiode saturation point changes with the incident beam size and investigates several models to explain the results. Bias Voltage examines the effects of incident power on the effective reverse bias voltage of a photodiode circuit and verifies a reliable model for predicting those changes.

Photodiode Saturation Limit and Noise Floor

About Our Lab Facts
Our application engineers live the experience of our customers by conducting experiments in Alex’s personal lab. Here, they gain a greater understanding of our products’ performance across a range of application spaces. Their results can be found throughout our website on associated product pages in Lab Facts tabs. Experiments are used to compare performance with theory and explore the benefits and drawbacks of using similar products in unique setups, in an attempt to understand the intricacies and practical limitations of our products. In all cases, the theory, procedure, and results are provided to assist with your buying decisions.

Pulsed Laser Emission: Power and Energy Calculations

Determining whether emission from a pulsed laser is compatible with a device or application can require referencing parameters that are not supplied by the laser's manufacturer. When this is the case, the necessary parameters can typically be calculated from the available information. Calculating peak pulse power, average power, pulse energy, and related parameters can be necessary to achieve desired outcomes including:

  • Protecting biological samples from harm.
  • Measuring the pulsed laser emission without damaging photodetectors and other sensors.
  • Exciting fluorescence and non-linear effects in materials.

Pulsed laser radiation parameters are illustrated in Figure 1 and described in the table. For quick reference, a list of equations are provided below. The document available for download provides this information, as well as an introduction to pulsed laser emission, an overview of relationships among the different parameters, and guidance for applying the calculations. 



Period and repetition rate are reciprocal:    and 
Pulse energy calculated from average power:       
Average power calculated from pulse energy:        
Peak pulse power estimated from pulse energy:            

Peak power and average power calculated from each other:
Peak power calculated from average power and duty cycle*:
*Duty cycle () is the fraction of time during which there is laser pulse emission.
Pulsed Laser Emission Parameters
Click to Enlarge

Figure 1: Parameters used to describe pulsed laser emission are indicated in the plot (above) and described in the table (below). Pulse energy (E) is the shaded area under the pulse curve. Pulse energy is, equivalently, the area of the diagonally hashed region. 

Parameter Symbol Units Description
Pulse Energy E Joules [J] A measure of one pulse's total emission, which is the only light emitted by the laser over the entire period. The pulse energy equals the shaded area, which is equivalent to the area covered by diagonal hash marks.
Period Δt  Seconds [s]  The amount of time between the start of one pulse and the start of the next.
Average Power Pavg Watts [W] The height on the optical power axis, if the energy emitted by the pulse were uniformly spread over the entire period.
Instantaneous Power P Watts [W] The optical power at a single, specific point in time.
Peak Power Ppeak Watts [W] The maximum instantaneous optical power output by the laser.
Pulse Width Seconds [s] A measure of the time between the beginning and end of the pulse, typically based on the full width half maximum (FWHM) of the pulse shape. Also called pulse duration.
Repetition Rate frep Hertz [Hz] The frequency with which pulses are emitted. Equal to the reciprocal of the period.

Example Calculation:

Is it safe to use a detector with a specified maximum peak optical input power of 75 mW to measure the following pulsed laser emission?

  • Average Power: 1 mW
  • Repetition Rate: 85 MHz
  • Pulse Width: 10 fs

The energy per pulse:

seems low, but the peak pulse power is:

It is not safe to use the detector to measure this pulsed laser emission, since the peak power of the pulses is >5 orders of magnitude higher than the detector's maximum peak optical input power.

Posted Comments:
Katherine Han  (posted 2024-05-20 11:40:45.14)
Hi, can you provide the IV curve for this photodiode at a specific illumination?
ksosnowski  (posted 2024-05-28 04:22:10.0)
Hello Katherine, Thanks for reaching out to Thorlabs. The photodiodes will act as a linear current source when below saturation so the output voltage will be determined by the load resistor used for measurement. We do not recommend operating the photodiode past the saturation point as the measurement is not reliable and photons can only convert to heat instead of electric current in this condition. InGaAs saturates at a fairly low photovoltaic level around 300mV depending on the exact photodiode, and typically a bias voltage is applied to directly extend the linear photoconductive range of output. The measurement load should be low enough so that the expected photocurrent will not exceed the biased or photovoltaic levels when considering Ohm's law for the measured voltage.
Yoshinori Matsumoto  (posted 2023-05-25 11:31:56.55)
Looking at the drawing of SM05PD2B, there is a set screw on the SMA connector side, can it be used to fix it to the chassis?
cdolbashian  (posted 2023-06-01 02:21:32.0)
Thank you for reaching out to us with your inquiry. I am not sure which "set screw" you are speaking of. I have reached out to you directly to clarify this. There is a locking nut on the SMA connector though this is mainly for locking the SMA cable in place. If you want to fix this to a chassis, I would recommend using the SM05 threadings on the outer, black-anodized, body of the component.
Osman Levent Şavkay  (posted 2023-05-17 22:25:32.097)
we have bought SM1PD1A Si Photodiode and AMP110 transimpedance amplifier. We applied the circuit diagram shown on the document of SM1PD1A and obtain the voltage output correctly. Now we want to use the AMP110 with SM1PD1A, please reccomend us a connection diagram for a setup using both products together. Best Regards, Levent Şavkay
dpossin  (posted 2023-05-17 09:58:52.0)
Dear Tolga, Thank you for your feedback. I am reaching out to you in order to provide the requested support.
Ao Teng  (posted 2022-01-30 23:38:49.973)
Hello, I'd like to inquire about how to fix this product. Do you have any products that can fix SM05PD3A? Thank you!
Dirk Hönig  (posted 2021-10-15 10:52:27.517)
Hello, we have purchased the SM1PD2A and found that the case is NOT connected to the BNC, opposite to the drawing in the online catalog. This fits to the fact that the BNC is an isolated one. I guess it's a copy/paste typo from the smaller SM05 diodes ? To get a low-noise measurement done with our TIA, we had to remove a bit of the case anodizing to connect the case to the shielding of a shielded double wire cable (microphone cable). What's missing in the data is a responsivity temperature coeff vs. wavelength graph (or at least UV, VIS, NIR regime values). In the Lab Facts section, you show extensive temperature measurements, but not on spectral responsivity, did I miss it somewhere? Thanks, Dirk
cdolbashian  (posted 2021-11-08 04:57:25.0)
Thank you for reaching out to us with this feedback Dirk. I have reached out to you directly to discuss your application. Regarding the "case", this is referring to the housing of the PD itself, rather than the anodized housing in which the photodiode is mounted within. For your specific application, we found that with a different cable (shielded 2-wire microphone cable), stripping of some of the anodized layer, and connecting the mounted housing to the alternative cable's ground, we were able to see a notable reduction in the ambient noise in this device. I have logged this internally as a potential improvement/alternate item for future releases.
Claudia Ruiz  (posted 2021-09-09 10:50:41.003)
Hello what is the SM05PD1A FOV? Thanks
cdolbashian  (posted 2021-09-20 01:42:39.0)
Thank you for contacting Thorlabs with this inquiry. The half-angle FOV for the component diode (FDS100) is 61 degrees from the center of the active area, measured from the normal. Since the housing obscures the FOV, the mounted version (SM05PD1A) has a half-angle FOV of approximately 39 degrees.
user  (posted 2021-09-04 18:09:33.997)
Could you please tell me the maximum input power (damage threshold) of SM05PD2A? Thank you very much!
cdolbashian  (posted 2021-09-20 01:32:53.0)
Thank you for contacting us at Thorlabs! The maximum input power depends directly on the responsivity, bias voltage, and termination of your device. Applying a bias voltage will determine the max output voltage measurable on your device, and thus the electrical saturation. While operating below the bias voltage, your laser's wavelength will determine the conversion of optical power to a photocurrent. We have a nice investigation of these behaviors here: I have contacted you directly with more information.
Niklas Papathanasiou  (posted 2021-08-19 03:21:04.89)
Hi, is it possible to get an SM05PD with a photodiode socket STO5P für TO5 photodiodes? I want to use my own (calibrate reference) photodiodes within the cage system at a fixed position. Or should I assaemble something on my own? best regards Niklas
cdolbashian  (posted 2021-08-26 03:43:44.0)
Thank you for reaching out to us here with this feedback Niklas. After discussing this with you directly, I have understood that you are looking for something similar to our strain-relief cables (used for laser diodes), but wired for photodiodes but with a PD socket. Unfortunately, this is not something we have at this time. We are, however, always hungry for feedback, and appreciate the suggestion!
Aadil Raza  (posted 2021-07-09 15:30:38.32)
Dear Sir May I know the modulation bandwidth of SM05PD6A - Large Area Mounted Germanium Photodiode, 800-1800 nm, Cathode Grounded. Can we use it for optical communication applications?
cdolbashian  (posted 2021-07-13 08:34:50.0)
Thank you for contacting Thorlabs! In general these devices can be used however you want to, assuming the functionality fits your needs. The particular photodiode you are looking at will have a rise time of 600ns and therefore can respond to a 10-90 modulated signal having a ~583kHz frequency (.35/rise time). I have emailed you directly to discuss your application.
Claudia Ruiz  (posted 2020-07-29 11:11:41.077)
Hello, Could you please provide the junction capacitance of SM05PD1A at 0V? thank youin advance, Claudia
YLohia  (posted 2020-07-29 11:11:56.0)
Hello Claudia, thank you for contacting Thorlabs. The corresponding component-level photodiode for these mounted detectors are given on the Specs on this page. The photodiode for the SM05PD1A is the FDS100: Clicking on the blue "info" icon on this link next to the part number brings up additional specs, which contains a Capacitance vs. Bias Voltage plot. We will make this more visible on this product page.
Youngki Kim  (posted 2020-07-23 01:59:06.89)
Is the photodiode compatible with other multimeters (not from Thorlab, for example, from Keysight, Newport...)?
YLohia  (posted 2020-07-23 10:55:59.0)
Thank you for contacting Thorlabs. Yes, these photodiodes are compatible with 3rd party multimeters and oscilloscopes.
Andrey Kuznetsov  (posted 2020-06-11 16:30:36.16)
Could Thorlabs offer standard product or provide quote for FD05D and FD10D devices mounted in SM05 housing like the SM05PD2A for example?
asundararaj  (posted 2020-06-12 08:29:51.0)
Thank you for contacting Thorlabs. Quotes can be requested by clicking the Request Quote button or by emailing I have contacted you directly regarding the custom offering.
giora chrmoni  (posted 2020-05-05 18:10:30.403)
hou i connect to FIBER OPTIC SC/apc ?
YLohia  (posted 2020-05-06 10:33:39.0)
Thank you for contacting Thorlabs. You can use the SM05SC adapter with the SM05M05 tube to connect an SC/APC fiber to the SM05PD4A. Please note that the fiber tip will need to be positioned relatively close to the sensor since the SM05SC will not correct for the tilt from the angled connector.
user  (posted 2019-11-29 06:19:27.34)
Hello, we need to know the electrical impedance of the SM1PD1A Photodiode (50 Ohm ?). We bought three of them to measured a pulsed signal (up to 10MHz). Thanks! Petra
asundararaj  (posted 2019-12-05 01:52:53.0)
Thank you for contacting Thorlabs. The SM1PD1A is a photodiode mounted in an BNC mount and does not have any external circuitry. 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.
Pawel Czuma  (posted 2019-10-14 06:37:17.177)
Dear Sir/Madam, I am looking for detector for measurement pulse-to-pulse stability of femtosecond amplified laser (1035nm, 515nm, 257nm) with pulse duration of 100fs at 50kHz plus oscillator 1035nm/73MHz/70fs. Please choose me appropriate avalanche/amplified photo-diode with description of maximum input average/peak pulse power, that will damage the detector Best Regards, Eng. Pawel Czuma, PhD
YLohia  (posted 2019-10-15 09:35:31.0)
Hello Pawel, thank you for contacting Thorlabs. Avalanche/amplified photodiodes do not have fast enough rise times to directly measure femtosecond pulses. You would have to use an autocorrelator such as our FSAC to measure such pulses.
g.d.j.sasbrink  (posted 2017-01-09 06:10:55.967)
Dear Thorlabs, I'm looking for a mounted, calibrated PD. The FDS100-CAL seems to be a suitable option. We do need the PD to be mounted however. The SM05PD1A seems to be the corresponding mounted product. I see that it is possible to obtain the SM05PD1A with a calibrated PD (as a custom product). What would be the price? Thanks.
tfrisch  (posted 2017-01-09 10:42:02.0)
Hello, thank you for contacting Thorlabs. We have been able to offer mounted calibrated photodiodes in the past. I will contact you directly about your needs.
bcaplins  (posted 2016-03-11 10:58:17.647)
I am planning to detect small signal from a 1 KHz laser with these PD's. I will be using a SRS 570 current amp which has a floating input. I was curious to know if there is any benefit to the cathode grounded vs anode grounded version? Seems like it shouldn't matter to me.
besembeson  (posted 2016-03-11 04:08:10.0)
Response from Bweh at Thorlabs USA: Yes it shouldn't really matter.
1982ariel  (posted 2015-01-15 15:28:34.47)
ThoeLabs hello, Please advise damage threshold on all your Si, GaAs,Ge and other detectors. Thank you Ariel
myanakas  (posted 2015-02-09 08:41:46.0)
Response from Mike at Thorlabs: We do not currently have damage threshold specifications for these photodiodes. We have contacted you directly to discuss you application.
robertmeissner  (posted 2014-11-20 16:11:23.863)
Dear Thorlabs, I want to measure the power of my laser with a SM1PD2A attached to an oscilloscope. I read that the maximum power is roughly a couple of mW. What is the maximum measurable voltage/current of this device? Could you tell me more about the I-V curve as well? Is a bias-voltage needed and if so, which voltage is needed?
jlow  (posted 2014-11-25 10:51:12.0)
Response from Jeremy at Thorlabs: The maximum reverse bias voltage is 5V. A reverse bias is not necessary but it will result in faster response and better linearity. We will contact you directly to discuss more about your application and provide more details.
holmiumht125  (posted 2014-10-03 12:53:33.787)
Dear Thorlabs, I would like to use the photodiode with an oscilloscope to measure the energy of laser pulse of ~10ns. For the same laser pulse, the signal looks very different for oscilloscope impedance of 50 Ohms and 1 MOhms. Which 1 should be used to measure energy of laser pulse? And how should be be calculated (min/max value, area under graph, etc)? Thanks.
jlow  (posted 2014-10-03 02:16:45.0)
Response from Jeremy at Thorlabs: These mounted photodiode are current source and you will not get a good signal for your application by using the oscilloscope with 1MOhm impedance. The 50Ohm input would be much better. You will also want to make sure to properly bias the photodiodes. For calculating the pulse energy, you will need a calibrated sensor which these mounted photodiodes are not. I will contact you directly to discuss more about your application and suggest something appropriate.
david.lee  (posted 2014-03-10 17:52:25.753)
Dear Thorlabs team, Do you have any information regarding the change in responsivity of the SM1PD1B photodiode as a function of temperature. I am interested in data for the temperature range 0C - 40C. Thank you.
jlow  (posted 2014-03-10 04:17:47.0)
Response from Jeremy at Thorlabs: The responsivity change will be more significant on the extreme ends of the responsivity curve. I will contact you directly to provide a typical graph for this.
th6187  (posted 2013-11-19 11:17:21.65)
Dear Thorlabs team, could you tell me damage threshold of the SM1PD1A and/or the recommended power range which this photodiode is suitable for? Thank you.
jlow  (posted 2013-11-21 10:59:27.0)
Response from Jeremy at Thorlabs: We recommend that the input power to be at most a few mW to make sure that the detector is not being saturated or operating in the nonlinear regime. As for the damage threshold, you would want to keep the detector output current to be <10mA.
ch605852  (posted 2013-10-27 13:37:37.607)
Is there any V-I characteristics of the diode itself? Specifically I am looking for information about output voltage respect to reverse bias and incident power. Thanks.
jlow  (posted 2013-10-29 14:19:00.0)
Response from Jeremy at Thorlabs: The output current should be linear with respect to the incident power up until a few mW. I will get in contact with you directly to discuss about this.
th6187  (posted 2013-07-15 14:30:03.043)
Dear Thorlabs team, do you have any information or data concerning a possible polarization dependence of the SM1PD1A? If so, I would be grateful if you could send it to me. Thanks, SR
jlow  (posted 2013-07-16 11:40:00.0)
Response from Jeremy at Thorlabs: The polarization effects depends on the angle of incidence (AOI). At 0° AOI, both s and p-polarization should yield the same result. I will get in contact with you to discuss about this further.
jlow  (posted 2012-07-31 17:44:00.0)
A response from Jeremy at Thorlabs: Thank you very much for your feedback. I have forwarded this to our engineering group and we will look into getting this implemented.
acable  (posted 2012-07-31 09:41:16.0)
I have modified your SM05PD1A sensor, the back end was to large to fit through a SM05 lens tube, by turning down the diameter of the unthreaded portion of the housing diameter to just below 0.450" i was able to get the parts to fit together nicely. Please consider reducing the diameter on all the detector housings so they fit into your standard lens tubes.
tcohen  (posted 2012-05-23 19:58:00.0)
Response from Tim at Thorlabs: Thank you for your feedback! We have found a couple errors on the web presentation that may have caused some confusion. We are confirming these values, will fix the errors and will clear up any ambiguity. Thank you for helping us improve our website!
user  (posted 2012-05-18 16:26:39.0)
There seems to be an error that has effected all you detector pages, looking at the NEP for the 0.8 mm^2 and 13 mm^2 area SI detectors in their various forms, the NEP values are different on the bare diode, package diodes from this page, and the biased detector pacakges. Please confirm the numbers, perhaps i am missing something and your packaging effects the NEP more than expected.
jvigroux  (posted 2011-12-02 12:09:00.0)
A response from Julien at Thorlabs: Thank you for your question. The cathode is connected to the housing and to the outer electrode of the BNC plug
strikovski  (posted 2011-11-30 09:15:26.0)
Please, clarify the electrical connection of the SM1PD2A: is Cathode directly connected to the diode case, and to BNC connector outer electrode? Sorry, that is not clear from your Spec Sheet. Thank you beforehand. Mikhail Strikovski NEOCERA LLC, USA
bdada  (posted 2011-10-17 14:07:00.0)
Response from Buki at Thorlabs: Thank you for your feedback. We will add more detailed drawings to our website soon. Please contact for further questions.
michael.vilcheck  (posted 2011-10-12 15:04:48.0)
The product drawings do not locate the detector plane. The drawing for the photodiode locates the plane relative to the front window, but the location of the photodiode within the delrin SM05 housing is not given. Could you please provide a drawing that locates the detector plane. Even better would be a solid model. Thank you, Michael
tor  (posted 2010-11-10 17:00:23.0)
Response to ericsmoll from Tor at Thorlabs: Thank you for your interest in the SM1PD1A. I will send a plot of the typical capacitance per unit area as function of reverse bias voltage. Our Electronics Department indicates that the capacitance is 1500pF for 0V and settles down to 300pF for 10V.
ericsmoll  (posted 2010-11-09 13:13:06.0)
Do you have a plot of SM1PD1A capacitance as a function of reverse bias?
lmorgus  (posted 2010-01-07 10:14:09.0)
Response from Laurie at Thorlabs to the anonymous poster: We are please to hear that you find the drawings on our overview tab helpful. We have enlarged those images to make the text easier to read. We hope these will be beneficial to you, and thank you for helping us to improve our website.
apalmentieri  (posted 2010-01-06 16:51:03.0)
A response from Adam at Thorlabs: You are correct, the text is rather small. We will enlarge the drawings on the overview tab to make them easier to read.
user  (posted 2010-01-06 16:18:14.0)
The drawings on the Overview tab are great as quick reference aids but i cant read the text, can you please enlarge.
Tyler  (posted 2008-04-14 16:58:02.0)
A response from Tyler at Thorlabs to tehola: I believe the best option Thorlabs can offer you with our stock parts to mount a TO-18 can photodiode on the optical axis of an SM05 lens tube is to use an S1LEDM mount in conjunction with an SM1A1. Note that unlike the mounted photodiodes that we sell, the S1LEDM is made from anodized aluminum and as a result the TO-18 can will not be insulated from the lens tube. I will forward your request to our design engineers. Hopefully, this will result in the development of a new product. Thank you for letting us know what kinds of tools you need for your lab.
tehola  (posted 2008-04-14 03:21:16.0)
Dear Sirs, It would be great, if you had such a product that could be used to mount a separate photodiode for example in TO-18 can to SM05 tube so that it is centered. Is it possible to get such a device at the moment from you and in what cost? -TH-

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

Photodetector Cross Reference
Wavelength Material Unmounted
Amplified Detector,
OEM Package
200 - 1100 nm Si FDS010 SM05PD2A
Si - SM1PD2A - - -
240 - 1170 nm B-Si - - DET20X2 - -
320 - 1000 nm Si - - - PDA8A2 -
320 - 1100 nm Si FD11A SM05PD3A - PDF10A2 -
Si - a - DET100A2 a PDA100A2 a PDAPC2 a
340 - 1100 nm Si FDS10X10 - - - -
350 - 1100 nm Si FDS100
FDS100-CAL b
Si FDS1010
FDS1010-CAL b
- - -
400 - 1000 nm Si - - - PDA015A2
400 - 1100 nm Si FDS015 c - - - -
Si FDS025 c
FDS02 d
- DET02AFC(/M)
- -
400 - 1700 nm Si & InGaAs DSD2 - - - -
500 - 1700 nm InGaAs - - DET10N2 - -
0.6 - 16 µm LiTaO3 - - - PDA13L2e -
750 - 1650 nm InGaAs - - - PDA8GS -
800 - 1700 nm InGaAs FGA015 - - PDA015C2 -
InGaAs FGA21
InGaAs FGA01 c
- DET01CFC(/M) - -
InGaAs FDGA05 c - - PDA05CF2 PDAPC6
InGaAs - - DET08CFC(/M)
- -
InGaAs - - - PDF10C2 -
800 - 1800 nm Ge FDG03
SM05PD6A DET30B2 PDA30B2 -
Ge FDG05 - - - -
900 - 1700 nm InGaAs FGA10 SM05PD4A DET10C2 PDA10CS2 -
900 - 2600 nm InGaAs FD05D - DET05D2 - -
950 - 1650 nm InGaAs - - - FPD310-FC-NIR
1.0 - 5.8 µm InAsSb - - - PDA10PT(-EC) -
2.0 - 8.0 µm HgCdTe (MCT) VML8T0
VML8T4 f
- - PDAVJ8 -
2.0 - 10.6 µm HgCdTe (MCT) VML10T0
VML10T4 f
- - PDAVJ10 -
2.7 - 5.0 µm HgCdTe (MCT) VL5T0 - - PDAVJ5 -
2.7 - 5.3 µm InAsSb - - - PDA07P2 PDAPC9
  • If you are interested in purchasing the bare photodiode incorporated in these detectors without the printed circuit board, please contact Tech Support.
  • Calibrated Unmounted Photodiode
  • Unmounted TO-46 Can Photodiode
  • Unmounted TO-46 Can Photodiode with FC/PC Bulkhead
  • Pyroelectric Detector
  • Photovoltaic Detector with Thermoelectric Cooler
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SM05-Threaded Mounted Photodiodes, Cathode Grounded

Pin Code A
SM05 Mounted Photodiode
Please click on the red document icons () below for the value of L.
Item # Detector
Time (Typ.)b
Active Area
Range (nm)
Material Junction
Reverse Bias
Voltage (Max)
SM05PD2A FDS010 1 ns / 1 ns @ 10 V 0.8 mm2 (Ø1.0 mm)c 5.0 x 10-14 0.3 nA @ 10 V 200 - 1100d Si 6 pF @ 10 V 25 V Efficiency Plot
SM05PD3Ae FD11A 15 ns / 15 nsf
@ 650 nm, 10 V
1.21 mm2 (1.1 x 1.1 mm) 4.2 x 10-15 20 pA (Typ.) @ 10 V
100 pA (Max) @ 10 V
320 - 1100 Si 140 pF @ 0 V 30 V Efficiency Plot
SM05PD1A FDS100 10 ns / 10 nsf
@ 632 nm, 20 V
13 mm2 (3.6 x 3.6 mm) 1.2 x 10-14 1.0 nA (Typ.) @ 20 V
20 nA (Max) @ 20 V
350 - 1100 Si 24 pF @ 20 V 25 V Efficiency Plot
SM05PD5A FGA21 25 ns / 25 ns @ 3 V 3.1 mm2 (Ø2.0 mm) 6.0 x 10-14 50 nA @ 1 V 800 - 1700 InGaAs 100 pF @ 3 V 3 V Efficiency Plot
SM05PD6A FDG03 600 ns / 600 ns
@ 3 V
7.1 mm2 (Ø3.0 mm) 2.6 x 10-12 4.0 µA (Max) @ 1 V 800 - 1800 Ge 6 nF @ 1 V
4.5 nF @ 3 V
3 V Efficiency Plot
SM05PD4A FGA10 10 ns / 10 ns @ 5 V 0.8 mm2 (Ø1.0 mm) 2.5 x 10-14 1.1 nA @ 5 V 900 - 1700 InGaAs 80 pF @ 5 V 5 V Efficiency Plot
  • Click the links to view specifications for the integrated photodiodes.
  • RL = 50 Ω
  • The Ø1 mm active area accounts for the two solder leads found on the photodiode face.
  • When 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.
  • Due to the mounting process, the NEP and dark current specifications of the SM05PD3A will differ from those of the FD11A.
  • The photodiode will be slower at NIR wavelengths.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
SM05PD2A Support Documentation
SM05PD2AMounted Silicon Photodiode, 200-1100 nm, Cathode Grounded
SM05PD3A Support Documentation
SM05PD3AMounted Silicon Photodiode, 320-1100 nm, Cathode Grounded
SM05PD1A Support Documentation
SM05PD1ALarge Area Mounted Silicon Photodiode, 350-1100 nm, Cathode Grounded
SM05PD5A Support Documentation
SM05PD5AMounted InGaAs Photodiode, 800-1700 nm, Cathode Grounded
SM05PD6A Support Documentation
SM05PD6ALarge Area Mounted Germanium Photodiode, 800-1800 nm, Cathode Grounded
SM05PD4A Support Documentation
SM05PD4AMounted InGaAs Photodiode, 900-1700 nm, Cathode Grounded
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SM05-Threaded Mounted Photodiodes, Anode Grounded

Pin Code B
SM05 Mounted Photodiode
Please click on the red document icons () below for the value of L.
Item # Detector
Rise/Fall Time
Active Area
Material Junction
Reverse Bias
SM05PD2B FDS010 1 ns / 1 ns
@ 830 nm, 10 V
0.8 mm2 (Ø1.0 mm) 5.0 x 10-14 0.3 nA (Typ.) @ 10 V 200 - 1100d Si 6 pF @ 10 V 25 V Efficiency Plot
SM05PD1B FDS100 10 ns / 10 nse
@ 632 nm, 20 V
13 mm2 (3.6 x 3.6 mm) 1.2 x 10-14 1.0 nA (Typ.) @ 20 V
20 nA (Max) @ 20 V
350 - 1100 Si 24 pF @ 20 V Efficiency Plot
  • Click the links to view specifications for the integrated photodiodes.
  • RL = 50 Ω
  • Typical Values
  • When 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.
  • The photodiode will be slower at NIR wavelengths.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
SM05PD2B Support Documentation
SM05PD2BMounted Silicon Photodiode, 200-1100 nm, Anode Grounded
SM05PD1B Support Documentation
SM05PD1BLarge Area Mounted Silicon Photodiode, 350-1100 nm, Anode Grounded
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SM1-Threaded Mounted Photodiodes, Cathode Grounded

Pin Code A
SM1 Mounted Photodiode

Unless otherwise noted, all measurements are performed at 25 °C.

Item # Detector
Rise/Fall Time
Active Area
Material Junction
Reverse Bias
SM1PD2A - 450 ns / 450 ns
@ 650 nm, 5 V
10 mm x 10 mm
Behind Ø9 mm
Clear Aperture
5.74 x 10-14 1.0 µA
(Max) @ 5 V
200 - 1100 Si 1.75 nF @ 0 V 5 V Resistivity Plot
SM1PD1A FDS1010 65 ns
@ 632 nm, 5 V
2.07 x 10-13 600 nA
(Max) @ 5 V
350 - 1100 Si 375 pF @ 5 V 25 V Resistivity Plot
  • Click the link to view specifications for the integrated photodiode.
  • RL = 50 Ω
  • The photodiode will be slower at NIR wavelengths.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
SM1PD2A Support Documentation
SM1PD2AMounted UV Enhanced Silicon Photodiode, 200-1100 nm, Cathode Grounded
SM1PD1A Support Documentation
SM1PD1AMounted Silicon Photodiode, 350-1100 nm, Cathode Grounded
Back to Top

SM1-Threaded Mounted Photodiode, Anode Grounded

Pin Code B
SM1 Mounted Photodiode
Item # Detector
Rise/Fall Time
Active Area
Material Junction
Reverse Bias
SM1PD1B FDS1010 65 ns
@ 632 nm, 5 V
10 mm x 10 mm Behind
Ø9 mm Clear Aperture
2.07 x 10-13 600 nA (Max) @ 5 V 350 - 1100 Si 375 pF @ 5 V 25 V Resistivity Plot
  • Click the link to view specifications for the integrated photodiode.
  • Typical Values; RL = 50 Ω
  • The photodiode will be slower at NIR wavelengths.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
SM1PD1B Support Documentation
SM1PD1BLarge Area Mounted Silicon Photodiode, 350-1100 nm, Anode Grounded
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DC Bias Module for Mounted Photodiodes

Bias Voltage -25 to + 25 V
Cutoff Frequencya 350 MHz
Photodiode Input Connector Female BNC
Output Connector Female SMA
DC Input Connector 2.5 mm Phono Jack (Cable Included)
Housing Dimensions 2.48" x 1.40" x 0.80"
(63.0 mm x 35.6 mm x 20.3 mm)
Operating Temperature 0 to 40 °C
Storage Temperature 0 to 40 °C
  • Determined by the Photodiode Used
  • Module for DC Biasing Our Mounted Photodiodes
  • Delrin®* Housing Isolates Connectors and Bias Source
  • Post Mountable via Bottom-Located 8-32 and M4 Taps

The PBM42 Bias Module allows a DC bias voltage from a user-supplied, external source to be applied to photodiodes. Designed for use with our mounted photodiodes, the module can accept an input bias voltage from -25 to +25 V from a user-supplied source and has a maximum bandwidth of 350 MHz (dependent on the photodiode).

The input side of the bias module has a BNC connector that can be connected to any of our mounted photodiodes equipped with the same connector by using a BNC cable or T3533 BNC adapter. Alternatively, the input side can be connected to any of our mounted photodiodes with SMA connectors by using an SMA-to-BNC cable or T4001 SMA-to-BNC adapter.

The bias module has an SMA connector on the output side and a 2.5 mm phono jack for the DC voltage input. A 36"-long cable with a 2.5 mm phono plug on one end and bare wires on the other is included with the module. Please note that the photodiode should be operated with a reverse bias. Forward biasing the photodiode can cause damage. For cathode-grounded photodiodes, the tip of the phono plug must be positive. For anode-grounded photodiodes, the tip of the phono plug must be negative. We recommend using a low-noise power supply with the module. For grounding and reverse bias voltage information on all our mounted photodiodes, please see the tables above.

For best frequency performance, the output of the bias module should be terminated with a 50 Ω cable and a 50 Ω impedance device or terminator, such as our T4119. For flexibility in output voltage, the VT2 variable terminator can also be used.

To ensure electrical isolation of the connectors and to protect the photodiode, the compact housing of the PBM42 is constructed from Delrin. Additionally, the housing offers one 8-32-tapped hole and one M4-tapped hole for mounting on our Ø1/2" posts, as shown on the Overview tab.

For more information, please see the full presentation on the PBM42 Bias Module.

*Delrin® is a registered trademark of DuPont Polymers, Inc.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
PBM42 Support Documentation
PBM42Bias Module for Mounted Photodiodes, BNC Input, SMA Output