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Unmounted Photodiodes

  • GaP, Si, InGaAs, Ge, and Dual Band (Si/InGaAs) Detectors Available
  • Available in TO Can, FC Connector, and Flat Wafer Body Styles
  • Available in Hermetically Sealed Packages











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Mounted and Unmounted Detectors
Unmounted Photodiodes (150 - 2600 nm)
Calibrated Photodiodes (350 - 1800 nm)
Mounted Photodiodes (150 - 1800 nm)
Pigtailed Photodiodes (320 - 1000 nm)
Photoconductors (1 - 4.8 µm)


  • GaP, Si, InGaAs, Ge, and Dual Band (Si/InGaAs) Detectors Available
  • Wavelength Ranges from 150 to 2600 nm

Thorlabs stocks a wide selection of discrete PIN junction photodiodes (PD) in various active area sizes and packages. These include indium gallium arsenide (InGaAs), gallium phosphide (GaP), silicon (Si), and germanium (Ge) photodiodes. We also offer five photodiode packages with enhanced performance characteristics: FGAP71, FDS015, FD05D, FD10D, and DSD2. The FGAP71, a GaP photodiode, is useful for detection of UV light sources from 150 to 550 nm. The FDS015 Si photodiode has a 35 ps rise time and a 0.65 pF junction capacitance, making it the highest speed, lowest capacitance photodiode offered below. The FD10D and FD05D are InGaAs photodiodes with high responsivity from 800 to 2600 nm, allowing detection of wavelengths beyond the normal 1800 nm range of typical InGaAs photodiodes. The DSD2 is a dual-band photodiode, which incorporates two photodetectors sandwiched on top of each other (Si substrate on top of an InGaAs substrate), offering a combined wavelength range of 400 to 1700 nm. 

To complement our photodiode product line, we offer mounted photodiodes and a range of compatible photodiode sockets. Please note that the PDs sold below are not calibrated, meaning responsivity will differ slightly from lot to lot; refer to the Response Variation tab for more information. We also offer calibrated photodiodes, which come with with NIST-traceable calibration, to correct for the differences in responsivity.

Many of our photodiodes can be reverse voltage biased using the PBM42 DC Bias Module for faster speed and higher optical power detection. For more 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. For more general information regarding the operation and terminology of photodiodes, refer to the Photodiode Tutorial tab.

Inhomogeneity on the edge of an active area of the detector can generate unwanted capacitance and resistance that distorts the time-domain response of a photodiode. 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.

The responsivity of a particular photodiode varies from lot to lot. Due to this, the photodiode you receive may have a slightly different response than what is represented below. For example, to the right, a graph for the FDS1010 photodiode shows the extent that the response may vary. This data was collected from 104 photodiodes. Minimum, Average, and Maximum responsivity was calculated at each data point and has been plotted.

To view typical responsivity vs. wavelength data for each individual photodiode, please click the Info buttons in the product specifications tables below.

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

This tab contains a collection of experiments performed at Thorlabs regarding the performance photodiodes we offer. Each section is its own independent experiment, which can be viewed by clicking "More [+]" to the right. Photodiode Saturation Limit and Noise Floor explores how different conditions, including temperature, resistivity, reverse-bias voltage, responsivity, and system bandwidth can effect noise in a photodiode's output. Photodiode Spatial Uniformity explores how spatial uniformity changes when varying the material of a photodiode or the wavelength of light incident on the diode; this section also includes spatial uniformity variance across multiple samples in a single product line. 

Photodiode Saturation Limit and Noise Floor
Beamsplitter Split Ratios
Click to Enlarge

Figure 1. Overview of the Photodiode's Response Curve,
Highlighting the Saturation Limit and the Noise Floor

We present laboratory measurements of the saturation limit and noise floor of a Thorlabs silicon photodiode. While all photodiodes function similarly, there are a number of parameters that affect the noise floor and saturation limit of a photodiode including the sensor temperature, resistivity, reverse bias voltage, responsivity, and system bandwidth. Here we investigated the effect of reverse bias voltage and load resistance within a silicon-based photodiode detection system. Increasing the reverse bias increased the saturation limit and had minimal effect on the noise floor. Decreasing the load resistance decreased the noise floor until reaching the noise of the measurement system, but also decreased the saturation limit. These results demonstrate some of the considerations necessary for choosing the reverse bias voltage and load resistance, and emphasize that noise sources within all of the components must be considered when creating a detection system.

For our experiment we used the FDS100 Si Photodiode as the photodiode under investigation. The collimated output of a fiber-pigtailed laser diode was used as the light source with output power from 0 to 50 mW. The collimated beam was incident upon a beamsplitter that transmitted the majority of the light to the photodiode under investigation and reflected the rest towards a reference power sensor. The photodiode response was then evaluated under various resistive loads and with different reverse bias voltages.

The plots to the right and below summarize the measured results for the various tested configurations. From these graphs the changes to the photodiode's linear response, noise floor, and saturation limit can be observed under different reverse voltage biases and load resistances. Figure 1 provides an overview of the photodiode response with a reverse voltage bias of 5 V and resistive load of 10 kΩ. The photodiode saturated at the upper limit of the response when the output photovoltage approached the reverse bias voltage. The noise floor at the lower limit of the response was a result of dark current and the thermal noise from the resistive load (Johnson noise). Figure 2 summarizes the results obtained using the photodiode with a 1 kΩ resistive load and various reverse bias voltages. It illustrates that the saturation limit can be raised by increasing the reverse bias voltage (within specification). Figure 3 summarizes the results from using the photodiode with a 5 V reverse bias voltage and various resistive loads. It illustrates that the slope of the photovoltage response increased as the load resistance was increased. Figure 4 summarizes the noise floor results obtained using a 0 V reverse bias voltage and various resistive loads. The noise floor increased when larger load resistances were used. It is important to note that the 1 kΩ data was measured above the theoretical Johnson noise due to the voltage noise within the measurement system. Minimal change in the overall noise floor was seen when using a 5 V reverse bias voltage. For details on the experimental setup employed and these summarized results, please click here.

Photodiode Response vs Bias
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Figure 2. Photovoltage Dependence on Reverse Bias Voltage
Photodiode Noise Floor
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Figure 4. Noise Floor with Various Resistive Loads
Photodiode Response vs Load
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Figure 3. Response with Various Resistive Loads

Photodiode Spatial Uniformity

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This is the optomechanical setup used to measure responsivity across a selection of photodiodes.

The output signal of a photodiode is a function of the responsivity, which is a ratio of the generated photocurrent to the power of the incident light. Responsivity is measured in amps per watt. While this value is typically assumed to be constant when the incident power is within a photodiode’s operating range, the responsivity can vary across its active area. How this variation manifests in a two dimensional space can be defined as spatial uniformity.

Each photodiode has an operating range, which we list on our specification sheets. Photons with wavelengths that fall in this operating range will have the proper energy to become absorbed within the crystal, exciting electrons and activating the photodiode. Features of a photodiode’s spatial uniformity will be observed differently depending on whether the wavelength of the light incident is above or below its operating range. In general, photons with wavelengths below the photodiode’s operating range have too much energy and are absorbed too near the surface of the crystal to activate it, causing loss in responsivity and an increase in heat. The severity of this loss is dictated mainly by the condition of the surface of the crystal. Photons with wavelengths above the photodiode’s operating range have energies too low and normally transmit through the crystal without interaction or heat the crystal. If defects or crystal misalignments exist in the bulk of the material, these low energy photons can contribute to responsivity and give false readings.

In this experiment, we demonstrate how spatial uniformity can vary due to semiconductor material and wavelength, and how responsivity can change from lot-to-lot within a product line.

In order to provide a better expectation of photodiode response across material, we characterized the typical uniformity of our Si, Ge, InGaAs, and GaP mounted photodiodes at their peak wavelength. For wavelength variations, we chose three photodiodes of different sensor materials measured at three wavelengths. Lastly, for lot-to-lot variations, eight SM1PD2A photodiodes were tested at their peak wavelength. The setup for taking these measurements consisted of an RC12APC-P01 collimator for use with multiple wavelengths. A 150 mm focal length lens and LTS150 stage were used to control the beam diameter incident upon the detector. The beam was created using our Superluminecent Diode series, save for measurements done at 405 nm, which used an S3FC405 benchtop laser source. The beam diameter used to scan each photodiode was dependent on the active area of the photodiode. Approximately 3600 measurements were taken in a 60 x 60 grid which encapsulated the photodiode's active area. To keep this resolution similar across all photodiodes, the beam size used for each photodiode varied between 50µm and 500µm. Two LNR50S motorized stages were used to translate the diode under this focusing beam. 

Each of the mounted photodiodes was scanned for a typical response curve near its peak wavelength. This consisted of scanning a source across the entire active area to characterize the response as a function of position. One diode for each of the Si, Ge, and InGaAs types was tested at two additional wavelengths to demonstrate the wavelength dependence of the responsivity features. The uniformity scans presented below are each normalized to the response value at the plot origin, corresponding to the center of the active area, and feature 0.25% contours.* Clicking the plots will enlarge them and display their scale bar. Note that the SM1PD5A is no longer available; its responsivity map has been retained here to provide an example of a Ge photodiode. 

Experimental Limitations
The values shown can only be regarded as typical for the diodes tested since a single diode was scanned for each part. While measurements are repeatable for these individual diodes, the uniformity variation for any diode is not guaranteed, because the responsivity can vary from lot to lot. Due to this, the photodiode you receive may have a slightly different response than what has been represented. 

The data collected show that the Ge and GaP photodiode have greater non-uniformity than the Si and InGaAs photodiodes. At the additional wavelengths tested for the three types, all three photodiode types showed the least amount of variation in response near the peak wavelength compared to other wavelengths. The lot-to-lot consistency showed similar spatial uniformity structure with few anomalous structures that would negatively affect photoresponse. 

*The SM05PD7A was contoured at 0.5%, and the SM1PD2A was contoured at 0.2%.

Below are the measured data displayed in contour maps of the tested photodiodes. Click "More [+]" to reveal the plots, and "Less [-]" to hide them again. 

Spatial Uniformity Plots at Their Peak Responsivity Wavelengths
Click Plots for Details
GaP Si InGaAs Ge

Spatial Uniformity Plots at Various Wavelengths
Click Plots for Details
405 nm 830 nm (Peak Wavelength) 1064 nm Responsivity Plot

830 nm 1064 nm 1550 nm (Peak Wavelength) Responsivity Plot

830 nm 1064 nm 1550 nm (Peak Wavelength) Responsivity Plot

Lot-to-Lot Consistency of SM1PD2A Photodiodes at Their Peak Responsivity Wavelength
Click Plots for Details

Dark Current as a Function of Temperature

Measurements of dark current as a function of temperature were acquired for several unmounted photodetectors. As is described in the following section, dark current is a relatively small electrical current that flows in p-n junction photodetectors when no light is incident on the detector. Measurements were taken for silicon (Si), germanium (Ge), gallium phosphide (GaP), and indium gallium arsenide (InGaAs) reverse-biased photodiodes over temperatures from 25 °C to approximately 55 °C. 

Figure 1: Current-Voltage Characteristic of a P-N Junction

Current-Voltage Characteristics of p-n Junction Photodiodes

The characteristic current-voltage relationship of p-n junction photodiodes, as diagrammed in Figure 1, possesses forward-biased and reverse-biased voltage regimes. In the reverse-biased voltage regime, in which p-n junction photodiodes are operated, a potential difference applied across the diode resists the flow of current.  Ideally, if no light is incident on a reverse-biased photodiode, no current flows.   

Under real-world conditions, random processes in the semiconductor material of the photodiode always generates current carriers (electrons and holes) that produce current. These current generation processes are not driven by the photogeneration of electrons and holes. Instead, they are largely driven by the thermal energy contained in the semiconductor material.[1] This dark current is generally small, but it is present when the photodiode is reverse biased and not illuminated. Dark current magnitudes vary for photodiodes of different material compositions; the efficiencies of the thermal generation processes depend on the type and crystal quality of the semiconductor used in the detector's sensing head. The magnitude of the dark current can be expected to increase as the temperature of the photodiode increases. 

When a photodiode is illuminated, the current generated by the incident light adds to the dark current. The carriers in the photocurrent are generated by the energy contained in the photons of the incident light. Above a certain illumination threshold intensity, the magnitude of the photocurrent exceeds the magnitude of the dark current. When the photocurrent is larger than the dark current, the magnitude of the photocurrent can be calculated by measuring the total current and then subtracting the contribution of the dark current. When the photocurrent is smaller than the dark current, the photocurrent is undetectable. Because of this, it is desirable to minimize the levels of dark current in photodiodes.

For convenience, both dark current and photocurrent are discussed as being independent of voltage over a range of voltages when the photodiode is reverse biased; however, the current flowing in real-world reverse-biased photodetectors is not completely independent of voltage over any voltage range. Regardless of whether the diode is illuminated, the current will increase as the magnitude of the reverse-bias voltage increases. In addition, if the reverse-bias voltage is increased beyond a certain threshold, the photodiode will suffer reverse breakdown, in which the magnitude of the current increases exponentially and permanent damage to the diode is likely.

Experiment: Dark Currents Measured for Packaged Photodiodes

Dark currents were measured over temperatures of 25 °C to approximately 55 °C for four representative unpackaged photodiodes: the Si-based FDS1010, the Ge-based FDG50, the GaP-based FGAP71, and the InGaAs-based FGA10.

DET in Nested-Box Test Fixture, Both Covers Open, Key Parts Labeled
Click to Enlarge

Figure 2: The Nested Metal Box Test Fixture with Covers Removed and FGA10 Installed
Black insulating foam lines the interiors of both boxes.  
A: Thermistor; B: FGA10; C: BNC-to-BNC Feedthrough; D: Outer Box; E: Inner Box; F: BNC-to-Triax Feedthrough; G: BNC-to-BNC Feedthrough 
Current Diagram Temperature Controller and Resistive Foil Heater
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Figure 4: An electrical circuit that included a resistive foil heater, TED8040 temperature controller, and two rectifying diodes controlled current flow through the resistive current heater as described in the text.   
Custom Temperature Test Chamber
Click to Enlarge

Figure 3: The Test Setup
The custom-built temperature chamber is on the top of the cart, and the temperature control instrumentation that includes the PRO800 and TED8040 cards is on the cart's lower shelf.

Experimental Setup
The experimental setup was designed to ensure a constant reverse-bias voltage across the photodiode, control the temperature of the detector, block light from reaching the detector, and establish an electrical path between the detector and the Keithley 6487 ammeter that isolated the measured current from extraneous electromagnetic interference (EMI) noise sources. Dark currents for these detectors can be on the order of nA, which made it important to control these conditions to ensure accurate measurements.

The detector enclosure consisted of a pair of nested aluminum metal boxes, which are shown with their covers off in Figure 2. Only one box would be required to create a light-tight environment for the photodiode, but an outer box was included in the setup to shield the inner box from EMI. The detector was placed inside the inner box, and it was electrically connected to the Keithly 6487 ammeter. The ammeter provided the required 5 V reverse-bias and received the output current signal. The electrical signals between the ammeter and the photodiode were routed through the two boxes using a combination of cables and feedthroughs. The 5 V bias voltage was connected to the photodiode using coax cables and BNC-to-BNC feedthroughs in the walls of both metal boxes. The current signal from the photodiode was connected to the BNC end of a BNC-to-Triax feedthrough integrated into the wall of the inner box. The signal was then routed through the outer box and to the Keithly 6487 using triax cables and a Triax-to-Triax feedthrough in the outer box. Triax cables were used because coax cables are poorly shielded, and using a coax cable to route the signal to the ammeter could introduce noise from EMI sources to the signal read from the detector. As the outer box shields the inner box from EMI, the noise introduced on the signal as it travels from the detector to the BNC-to-Triax feedthrough is mitigated.

Thermistors were used to monitor the temperatures of each photodiode continuously during the experiment. A piece of thermal tape was used to hold the thermistor flush against the TO cans of the FDG50, FGAP71, and the FGA10 during testing. The photosensor of the FDS1010 is mounted on a ceramic substrate, and when it was tested the thermistor was taped to the back of the substrate. The electrical connection between the thermistor and TSP01 temperature logger was performed using BNC cables, BNC-to-BNC bulkhead feedthroughs to route the signal out of the nested boxes, and a custom BNC-to-phono jack cable to connect to the temperature logger.

A custom temperature chamber based on a XE25C9 standard enclosure was used to conduct these tests. It is shown on top of the cart in Figure 3. The enclosure had a floor and four walls, and insulation was attached to all inner and outer surfaces. A lid for the enclosure was fashioned from a sheet of hardboard bordered with XE25 rails, and insulation was attached to the inner surface of the hardboard. Six resistive foil heaters were affixed to the walls of the XE25C9 enclosure, and they were driven using the PRO8000 fitted with six TED8040 thermoelectric cooler (TEC) controller cards placed on the bottom shelf of the cart in Figure 3. Each TED8040 was interfaced with a heater and a thermistor installed in the chamber. The reading from the thermistor determined the current sent to drive the heater. The chamber was not actively cooled; cooling was instead performed by withdrawing the current driving the heaters and, as an option, opening the lid of the chamber. 

The TED8040 units are designed to be interfaced with TECs, which produce heat when current flows in one direction, and which provide cooling when the current flows in the opposite direction. Because of this, when the enclosure exceeded the setpoint temperature, the TED8040 units in this experimental setup did not cut off the driving current. They instead reversed the current flow in an effort to produce cooling. In contrast to TECs, resistive foil heaters generate heat regardless of the direction of current flowing through them. In order to divert the driving current from the heaters, an electrical circuit, diagrammed in Figure 4, that included two rectifying diodes was designed and implemented. Rectifying diodes allow current to flow only in one direction. When the temperature reading from the thermistor was lower than the setpoint temperature, current flowed in the direction of the red arrows and through the resistive heater, and heat was generated. When the temperature of the enclosure exceeded the setpoint temperature, the TED8040 controllers reversed the direction of the current, so that it flowed in the direction of the blue arrows. Under this condition, the circuit diverted the current from the heaters and the chamber was allowed to cool.

Experimental Results
The data curves plotted in Figure 5 are the dark currents measured for the Si-based FDS1010, the Ge-based FDG50, the the GaP-based FGAP71, and the InGaAs-based FGA10. Data were acquired continuously while the temperature was between 25 °C and 55 °C (shaded region of Figure 6). Figure 6 is representative of the temperature measured at the photodiode during the experiment. The temperature profile included an initial segment of increasing temperature, followed by a soak that allowed the photodiode to reach the maximum temperature, and concluded with a cool-down. The data plotted in Figure 5 include all dark current measurements measured between 25 °C and 55 °C; current measurements taken at the same temperature, but at different times, overlay one another for each diode. 

The data curves plotted in Figure 5 show that the measured dark current magnitudes differed depending on the material composing the photodiode. From lowest to highest:

  • GaP-Based Detector FGAP71 (Lowest Dark Current) 
  • InGaAs-Based Detector FGA10
  • Si-Based Detector FDS1010
  • Ge-Based Detector FDG50 (Highest Dark Current)

These span approximately 6 orders of magnitude. In all cases, the dark current increased with the temperature of the photodiode, as expected. The individual points on this graph, plotted as diamonds, are the values of the dark current specified for each detector at 25 °C. These points specify a maximum value of dark current at 25 °C; each diode's dark current must be equal to or less than this value at 25 °C, but the dark current may exceed this specification at higher temperatures, as is the case for all but the measured FDS1010 detector.

Dark Current Measurement Data
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Figure 5: Dark Current Data Measured for Four Unmounted Photodiodes
The discrete data points, plotted as diamonds, are values of the dark current specified for each detector at 25 °C.
Temperature Profile for the Dark Current Measurement Data
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Figure 6: Temperature of a Representative Photodiode Controlled by the Conditions in the Environmental Chamber
Dark current measurements were acquired between 25 °C and 55 °C (indicated by the shaded region) and are plotted in Figure 5 .

Experimental Limitations
Measurements were performed using a single representative of each detector type, as these data were intended to illustrate overall trends. These data should not be taken as specific for a particular diode. The measured dark current is a function of voltage bias, temperature dependence of resistive loads, and other effects. Efforts were made to suppress their influence on these measurements, including using the Keithly 6487 ammeter to provide the required 5 V reverse bias.  Using the ammeter removed the need to use a load resisitor, which may exhibit its own temperature dependence. The thermistor was placed as close to the semiconductor sensor as was possible, but it was not placed in direct contact with the sensor. Because of this, there may have been a difference between the measured temperature and the temperature of the semiconductor material. The dark current was measured while the temperature of the environmental chamber was continuously varied. Humidity was not controlled during this experiment.

 [1] J. Liu, Photonic Devices. Cambridge University Press, Cambridge, UK, 2005

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 look at 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.

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Posted Comments:
Posted Date:2017-02-01 12:49:31.84
How large of a fiber optic core can the the FDS02 photo-diode be used with before coupling efficiency drops?
Posted Date:2017-02-16 02:14:08.0
Hello, thank you for contacting Thorlabs. While the active area is 250um in diameter, the largest fiber we have that is smaller than that would be a 200um core. The FDS02 does not include a ball lens between the fiber and the detector. I will reach out to you with more details.
Posted Date:2016-03-22 21:36:37.053
Hi, is the FGA01FC a multi-quantum-well structure photodiode?
Posted Date:2016-03-25 12:26:10.0
Response from Bweh at Thorlabs USA: The FGA01FC is not a multi-quantum-well structure. This is simply a doped InGaAs material to create a P-N junction for charge transfer when illuminated by light of suitable wavelength. Quantum wells on the other hand are heterostructure made by joining materials, in layers at the atomic level, which typically leads to an emission.
Posted Date:2016-02-29 14:16:38.723
Please I need a Photodector with wide sensing area, a wavelength of 650nm and which comes with an SMA Connector
Posted Date:2016-03-09 12:16:53.0
Response from Bweh at Thorlabs USA: The SM05PD1A (Large Area Mounted Silicon Photodiode, 350-1100 nm, Cathode Grounded) could be a suitable recommendation. Others can be found at the following link on our website:
Posted Date:2015-10-16 14:16:32.147
What is the series and shunt resistance of FDS100?
Posted Date:2015-10-27 04:54:33.0
Response from Bweh at Thorlabs USA: We don't have the exact values from the manufacturer of the photodiode but the shunt resistance should be in the Giga Ohm range while the series resistance should be extremely low that it can be negligible.
Posted Date:2015-09-24 03:41:03.583
Do you offer calibration for the DSD2 photodiode? Thanks!
Posted Date:2015-10-08 12:06:35.0
Response from Bweh at Thorlabs USA: This is not possible for the DSD2. There is a limitation to the minimum detector size for us to do such calibration, which is 2mm minimum. The InGaAs sensor is only about 1.5mm.
Posted Date:2015-03-24 10:27:03.187
I would need a photodiode set up with specific mount (3pcs) for picosecond laser alignment. Focused spot size (1/e2) is <100µm. Succesfull guidance will mean purchase..
Posted Date:2015-03-24 04:42:43.0
Response from Jeremy at Thorlabs: We will need more information on your application first. We will contact you directly about this.
Posted Date:2014-05-09 07:48:19.477
Dear ladies and gentlemen, I am looking for a Si photodiode for a stimulated raman microscope, where the modulation of a ps-laser beam must be detected. The diode has to work in MHz range, quite large active area and must be sensitive between 800 and 1000nm. Up to now I thought about the DET100A. But now I have doubts that it will saturate to fast. Can you suggest another diode, which saturates at high powers to detect the laser beam. Best regards André Klossek
Posted Date:2014-05-13 08:43:47.0
Response from Jeremy at Thorlabs: I will contact you directly to get more information on your application and make a recommendation.
Posted Date:2013-05-05 06:39:49.27
Could you like to tell me the damage threshold of FGA10 ?
Posted Date:2013-05-09 11:19:00.0
Response from Jeremy at Thorlabs: I would recommend keeping the output current to be <10mA to avoid the internal wire in the FGA10 from failing. You can estimate the output current for your input power and wavelength from the responsivity graph on the 2nd page of the spec sheet at
Posted Date:2012-10-24 16:14:00.0
Response from Jeremy at Thorlabs: There's a ball lens covering the chip and it is not AR coated.
Posted Date:2012-10-18 13:30:14.92
Is there a window or a ball lens covering the chip? Is the window or ball lens AR coated? If so, for which wavelength is it optimized? Thank you! Tilman
Posted Date:2012-09-05 09:15:00.0
Response from Jeremy at Thorlabs: I will get in contact with you directly to discuss about your application.
Posted Date:2012-09-03 10:17:41.0
Hi, I’m a researcher in South of Korea Recently, I am developed infrared moisture detector. And I used LED and PD that is your product. I have a question. What is the question PD, LD(laser diode) and LED that use infrared moisture detector or infrared moisture analyzer? Recently, What other companies use the LED, PD that used the water detector of Commercial products? And what is commercial product? And, If you will give a detailed information about the LED, PD. I appreciate your help.
Posted Date:2012-08-23 16:31:00.0
Response from Jeremy at Thorlabs: The junction capacitance between 4V and 5V is pretty much flat. Unfortunately we do not have any data on the capacitance and fall time specs beyond 5V.
Posted Date:2012-08-22 06:14:07.0
I would like to use this diode as a detector for microwave modulated light, but the fall time at 5V is too high. How much doe the capacitance and fall time change when the bias voltage is increased?
Posted Date:2012-08-17 11:16:00.0
Response from Jeremy at Thorlabs: We are not able to disclose the thicknesses for the PIN layers.
Posted Date:2012-08-17 09:50:00.0
Is there a way to get find out the thickness of the p, i and n regions of the FDS010 diodes? Thank you.
Posted Date:2012-08-16 13:42:00.0
Response from Jeremy at Thorlabs: I will get in contact with you directly for the Excel spreadsheet. Please note that the spectral responsivity of your photodiode can be quite different than what is shown online. One alternative to using the FDS100 is the FDS100-CAL ( which is the NIST calibrated version of the FDS100.
Posted Date:2012-08-16 12:13:51.0
Is the raw spectral responsivity data for the FDS100 available in an Excel spreadsheet? I'd like to get a more exact A/W value for my specific wavelengths of interest. Thanks!
Posted Date:2012-03-22 14:27:00.0
Response from Tim at Thorlabs: Thank you for your feedback. If the window is removed the diode can be easily damaged and absorb water from the atmosphere. This will be detrimental to the performance of the FGA10. If the window is removed we recommend storing it in an N2 dry box.
Posted Date:2012-03-22 13:31:41.0
Can you tell me if the performance of the FGA10 will degrade if its window is removed?
Posted Date:2012-03-16 12:33:00.0
Response from Buki at Thorlabs: Thank you for your suggestion. We will work on adding dark current vs bias voltage charts to our website.
Posted Date:2012-03-15 19:02:40.0
Please consider adding a plot that shows the dark current as a function of bias voltage.
Posted Date:2012-01-31 23:43:00.0
Response from Buki at Thorlabs: The temperature does have a slight effect on the responsivity, but mostly in near the bandgap region. We have sent you some typical curves to review.
Posted Date:2012-01-30 12:27:49.0
I am currently working with a FDG05 and I notice that the efficiency changes with temperature, as indicated also in the datasheet. Is it available any data regarding the expected change in responsivity as funcion of temperature?
Posted Date:2011-07-07 09:57:00.0
Response from Javier at Thorlabs to jasiel.mora: Thank you very much for contacting us! We actually show a recommended circuit diagram for our photodiodes on their spec sheets. Take a look at the spec sheet for the FDG03 here: I will contact you directly in case you have any further questions.
Posted Date:2011-07-06 16:42:48.0
Could you please sugest any connection diagram for the sensor FDG03? Thanks.
Posted Date:2011-04-20 12:09:00.0
Response from Javier at Thorlabs to last poster: Thank you very much for contacting us. The shunt resistance of the FDS1010 photodiode is in the range of 50-200 MOhm (@ 10 mV reverse bias). Also, we have added a graph of the maximum, average, and minimum responsivity values for the FDS1010 (See Responsivity Graphs tab). Please contact us at if you have any further questions or comments.
Posted Date:2011-04-20 13:08:43.0
What is the shunt resistance of FDS1010? Its not in the specs. A typ. and min. responsivity value would be useful as well.
Posted Date:2011-01-18 16:08:51.0
A response from Julien at Thorlabs: The FGA04 can only be calibrated at a predefined fixed wavelength by using a fiber coupled laser source. A calibration over the whole wavelength range of this photodiode is unfortunately not possible due to its small active area. Such a calibration would be made in free space using a monochromator, whose output beam diameter is about 1.5mm. Such a beam would largely overfill the active sensor area, and thus make the calibration highly inaccurate. You can contact our tech support ( to further discuss which solutions could be adapted to your need
Posted Date:2011-01-18 17:46:35.0
why a NIST-traceable calibration is not possible for FGA04? Im looking for a fiber-coupled detector that is provided with calibration.
Posted Date:2010-10-28 13:45:47.0
Our FDG05 are failing roughly 3 months of use. What is the expected life of these detectors? We are exposing indirect UV light around 5W/cm2 of intensity to the LADs. Could this be of a concern?
Posted Date:2010-10-28 15:01:31.0
Response from Javier at Thorlabs to kleap: at 5 W/cm^2, the detector will most likely be saturated; however, we specify a damage threshold of 10 W/cm^2 for the FDG05, so I do not expect excessive power to be the reason for failure. Also, we do not have a lifetime spec, since there are too many factors involved. I will contact you directly to troubleshoot your application.
Posted Date:2010-07-23 14:06:31.0
Response from Javier at Thorlabs to ranutyagi: Thank you for your feedback. With an input of 10 mW, you will most likely end up damaging your photodiodes. As a guideline, we specify a maximum input power density of 100 mW/cm^2. So, for example, if we assume that you have a 10 mW, 2 mm diameter beam at the input, the resulting power density is ~333mW/cm^2, which clearly exceeds the damage threshold. For linear operation of the photodiode, we recommend limiting the input to ~ 1 mW. Above this value, the diode undergoes saturation and, eventually, damage.
Posted Date:2010-07-23 07:03:58.0
I am using FDS100 and FDS010 with CW 10mW peak power laser diode. will it be damaging my photodiode? How much is the maximum input power these diodes can sustain.
Posted Date:2010-04-29 16:58:35.0
A response from Adam at Thorlabs to marcoc: Saturation occurs for these diodes at approximately 10mW. We would suggest using these diodes with peak and average powers that are less than 10mW if you want to avoid saturation.
Posted Date:2010-04-29 16:51:34.0
Any idea about the saturation for pulsed (50fs) laser beam at 800 nm ? thanks marco
Posted Date:2010-01-14 15:34:33.0
A response from Adam at Thorlabs to Curtis: The operating and storage temperature ranges for the FDS100 are the following: -25 to +85 deg C operating, -40 to +100 deg C storage.
Posted Date:2010-01-14 15:12:09.0
Dear Sirs, I have several FDS100 photodiodes and would like to know the allowable temperature ranges for operation and storage. Regards, Curtis Ihlefeld
Posted Date:2009-08-07 14:16:56.0
Dear Thorlabs, It would be nice to have the wavelength response for the FDS02 plotted on the Graphs page. I found the graph on the spec sheet, but it would be nice to see it plotted on the same graph as the rest of the FDS series. Regards, Dan
Posted Date:2009-02-02 09:25:34.0
A response from Tyler at Thorlabs to ocarlsson: The FGA04 spec sheet available under the Drawings and Documents tab lists the max forward current as 10 mA and the damage threshold at 70 mW. The damage threshold is the point at which the photodiode sensor will fail, however, internal wires in the FGA04 package will fail when the forward current exceeds 10 mA. Use the responsivity curve in the spec sheet to approximate the forward current for a given wavelength or contact our technical support department for assistance. An optical fiber attenuator like the FA05T, FA10T, FA15T, or FA25T can be used in to reduce the power in the optical fiber to a level that is safe to use with the FGA04. Thank you for your question, I will be adding a note to the bottom of the table on the Specs tab to help future customers with this issue.
Posted Date:2009-01-16 02:31:20.0
The FGA04 max current is 10mA and damage threshold is 100mW. Responsivity 0.8. How is the damage threshold calculated? Best regards Olle

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 - 1000 nm Si - - - - PDA015A
400 - 1100 nm Si FDS015 b - - - -
Si FDS025 b
FDS02 c
- - DET02AFC
400 - 1700 nm Si & InGaAs DSD2 - - - -
500 - 1700 nm InGaAs - - DET10N - -
800 - 1700 nm InGaAs FGA015 - - - PDA015C
InGaAs FGA21
- SM05PD5A - PDA20C
InGaAs FGA01 b
- - DET01CFC -
InGaAs FDGA05 b - - - 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

GaP Photodiode - UV Wavelengths

  • Detection of Extremely Short Wavelengths (150 - 550 nm)
  • Fast 1 ns Rise Time
  • Mounted in a Hermetically Sealed Package with a Sapphire Window
Item # Info Wavelength
Package Rise/Fall
FGAP71 info 150 - 550 nm 4.8 mm2
(2.2 mm x 2.2 mm)
TO-39 1 ns / 140 ns
@ 5 V
1.3 x 10-14
@ 440 nm, 5 V
40 pA (Typ.)
@ 5 V
1000 pF @ 0 V STO5S
  • Typical Values; RL = 50 Ω
Based on your currency / country selection, your order will ship from Newton, New Jersey  
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FGAP71 Support Documentation
FGAP71GaP Photodiode, 1 ns Rise Time, 150-550 nm, 2.2 mm × 2.2 mm Active Area

Si Photodiodes - VIS Wavelengths

Click Image
for Details
FDS010 FDS10X10 FDS100 FDS1010 FDS1010 FDS02 FDS025
Item # FDS010 FDS10X10 FDS100 FDS1010 FDS015 FDS02 FDS025
Key Feature UV Grade Fused Silica Window to Provide Sensitivity Down to 200 nm Low Dark Current in 10 mm x 10 mm Cematic Package Largest Sensor in a TO-5 Can Large Active Area and Mounted on an Insulating Ceramic Substrate Highest Speed and Lowest Capacitance in a TO-46 Can with an AR-Coated Window High Speed and Low Capacitance in a Direct Fiber-Coupled FC/PC Package High Speed and Low Capacitance in a TO-46 Can with a Ball Lens
Info info info info info info info info
Wavelength Range 200 - 1100 nm 340 - 1100 nm 350 - 1100 nm 350 - 1100 nm 400 - 1100 nm 400 - 1100 nm 400 - 1100 nm
Active Area 0.8 mm2
(Ø1.0 mm)
100 mm2
(10 mm x 10 mm)
13 mm2
(3.6 mm x 3.6 mm)
100 mm2
(10 mm x 10 mm)
0.018 mm2
(Ø150 µm)
0.049 mm2
(Ø0.25 mm)
0.049 mm2
(Ø0.25 mm)
Rise/Fall Time 1 ns / 1 nsa
@ 830 nm, 10 V
150 ns / 150 nsa
@ 5 V
10 ns / 10 nsb
@ 20 V
65 ns / 65 nsb
@ 5 V
35 ps / 200 psa
@ 850 nm, 5 V
47 ps / 246 psa
@ 850 nm, 5 V
47 ps / 246 psa
@ 850 nm, 5 V 
NEP 1.2 x 10-13 W/Hz1/2
@ 830 nm, 10 V
1.50 x 10-14 W/Hz1/2
@ 960 nm
1.2 x 10-14 W/Hz1/2
@ 900 nm, 20 V
2.07 x 10-13 W/Hz1/2
@ 970 nm, 5 V
8.60 x 10-15 W/Hz1/2
@ 850 nm, 5 V
9.29 x 10-15 W/Hz1/2
@ 850 nm, 5 V
9.29 x 10-15 W/Hz1/2
@ 850 nm, 5 V
Dark Current 0.3 nA (Typ.) @ 10 V 200 pA @ 5 V 1.0 nA (Typ.) @ 20 V 600 nA (Max) @ 5 V 0.03 nA (Typ.) @ 5 V 35 pA (Typ.) @ 5 V 35 pA (Typ.) @ 5 V
6 pF (Typ.) @ 10 V 380 pF @ 5 V 24 pF (Typ.) @ 20 V 375 pF (Typ.) @ 5 V 0.65 pF (Typ.) @ 5 V 0.94 pF (Typ.) @ 5 V 0.94 pF (Typ.) @ 5 V
Package TO-5 Ceramic TO-5 Ceramic TO-46 TO-46, FC/PC Bulkhead TO-46
Not Available STO5S
Not Available STO46S
  • Typical Values; RL = 50 Ω
  • Specified at 632 nm, Resistor Load = 50 Ω. PD will be slower at NIR wavelength.
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FDS010 Support Documentation
FDS010Si Photodiode, 1 ns Rise Time, 200 - 1100 nm, Ø1 mm Active Area
FDS10X10 Support Documentation
FDS10X10Si Photodiode, 150 ns Rise Time, 340 - 1100 nm, 10 mm x 10 mm Active Area
FDS100 Support Documentation
FDS100Si Photodiode, 10 ns Rise Time, 350 - 1100 nm, 3.6 mm x 3.6 mm Active Area
FDS1010 Support Documentation
FDS1010Si Photodiode, 65 ns Rise Time, 350 - 1100 nm, 10 mm x 10 mm Active Area
FDS015 Support Documentation
FDS015NEW!Si Photodiode, 35 ps Rise Time, 400 - 1100 nm, Ø150 µm Active Area
FDS02 Support Documentation
FDS02Si Photodiode, 47 ps Rise Time, 400 - 1100 nm, Ø0.25 mm Active Area, FC/PC Bulkhead
FDS025 Support Documentation
FDS025Si Photodiode, 47 ps Rise Time, 400 - 1100 nm, Ø0.25 mm Active Area

InGaAs Photodiodes - NIR Wavelengths

Click Image
for Details
Item # FGA01 FGA01FC FGA015 FDGA05 FGA21 FD05D FD10D FGA10
Key Feature High Speed and Low Capacitance in a TO-46 Can with a Ball Lens High Speed and Low Capacitance in a Direct Fiber-Coupled FC/PC Package High Speed and Low Capacitance High Speed, High Responsivity, and Low Capacitance Large Active Area and High Speed Long Wavelength Range Long Wavelength Range and Large Active Area High Speed and Low Dark Current
Info info info info info info info info info
Wavelength Range 800 - 1700 nm 800 - 1700 nm 800 - 1700 nm 800 - 1700 nm 800 - 1700 nm 800 - 2600 nm 800 - 2600 nm 900 - 1700 nm
Active Area 0.01 mm2
(Ø120 µm)
0.01 mm2
(Ø120 µm)
0.018 mm2
(Ø150 µm)
0.196 mm2
(Ø0.5 mm)
3.1 mm2 (Ø2 mm) 0.20 mm2
(Ø0.5 mm)
0.79 mm2
(Ø1.0 mm)
0.79 mm2 (Ø1 mm)
Rise/Fall Timea 300 ps / 300 ps
@ 5 V
300 ps / 300 ps
@ 5 V
300 ps / 300 ps
@ 1550 nm, 5 V
2.5 ns / 2.5 ns
@ 5 V
14 ns / 14 ns
@ 3 V
17 ns / 17 ns
@ 0 V
25 ns / 25 ns
@ 0 V
10 ns / 10 ns
@ 5 V
NEP 4.5 x 10-15 W/Hz1/2
@ 1500 nm
4.5 x 10-15 W/Hz1/2
@ 1500 nm
1.3 x 10-14 W/Hz1/2
@ 1550 nm
0.8 x 10-14 W/Hz1/2
@ 1550 nm
3.0 x 10-14 W/Hz1/2
@ 1550 nm
5.0 x 10-13 W/Hz1/2
@ 2300 nm
1.0 x 10-12 W/Hz1/2
@ 2300 nm
2.5 x 10-14 W/Hz1/2
@ 900 nm, 2 V
Dark Current 0.05 nA (Typ.)
@ 5 V
0.05 nA (Typ.)
@ 5 V
0.5 nA (Typ.)
@ 5 V
6 nA (Typ.)
@ 5 V
50 nA (Typ.)
@ 1 V
1 µA (Typ.)
@ 0.5 V
3 µA (Typ.)
@ 0.5 V
1.1 nA (Typ.)
@ 5 V
2.0 pF (Typ.) @ 5 V 2.0 pF (Typ.) @ 5 V 1.5 pF (Typ.) @ 5 V 10 pF (Typ.) @ 5 V 100 pF (Typ.) @ 3 V 140 pF (Typ.) @ 0 V 500 pF (Typ.) @ 0 V 80 pF (Typ.) @ 5 V
Package TO-46 TO-46, FC/PC Bulkhead TO-18 TO-46 TO-5 TO-18 TO-18 TO-5
  • Typical Values; RL = 50 Ω
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
FGA01 Support Documentation
FGA01InGaAs Photodiode, 300 ps Rise Time, 800-1700 nm, Ø0.12 mm Active Area
FGA01FC Support Documentation
FGA01FCInGaAs Photodiode, 300 ps Rise Time, 800-1700 nm, Ø0.12 mm Active Area, FC/PC Bulkhead
FGA015 Support Documentation
FGA015NEW!InGaAs Photodiode, 300 ps Rise Time, 800-1700 nm, Ø150 µm Active Area
FDGA05 Support Documentation
FDGA05InGaAs Photodiode, 2.5 ns Rise Time, 800-1700 nm, Ø0.5 mm Active Area
FGA21 Support Documentation
FGA21InGaAs Photodiode, 14 ns Rise Time, 800-1700 nm, Ø2 mm Active Area
FD05D Support Documentation
FD05DInGaAs Photodiode, 17 ns Rise Time, 800-2600 nm, Ø0.5 mm Active Area
FD10D Support Documentation
FD10DInGaAs Photodiode, 25 ns Rise Time, 800-2600 nm, Ø1.0 mm Active Area
FGA10 Support Documentation
FGA10InGaAs Photodiode, 10 ns Rise Time, 900-1700 nm, Ø1 mm Active Area

Ge Photodiodes - NIR Wavelengths

Click Image
for Details
Item # FDG03 FDG05a FDG50 FDG10X10
Key Feature Large Active Area in a TO-5 Can High Speed on a Ceramic Substrate Large Active Area in a TO-8 Can Largest Active Area
Info info info info info
Wavelength Range 800 - 1800 nm 800 - 1800 nm 800 - 1800 nm 800 - 1800 nm
Active Area 7.1 mm2 (Ø3 mm) 19.6 mm2 (Ø5 mm) 19.6 mm2 (Ø5 mm) 100 mm2
(10 mm x 10 mm)
Rise/Fall Timeb 500 ns / 500 ns @ 3 V 220 ns / 220 ns @ 3 V 220 ns / 220 ns (Typ.) @ 10 V 10 μs (Typ.) @ 1 V
NEP 1.0 x 10-12 W/Hz1/2 @ 1550 nm 4.0 x 10-12 W/Hz1/2 @ 1550 nm 4.0 x 10-12 W/Hz1/2 @ 1550 nm 4.0 x 10-12 W/Hz1/2 @ 1550 nmc
Dark Current 4.0 µA (Max) @ 1 V 40 µA (Max) @ 3 V 60 µA (Max) @ 5 V 50 µA (Max) @ 0.3 V
Junction Capacitance 3250 pF (Typ.) @ 1 V 3000 pF (Typ.) @ 3 V 1800 pF (Max) @ 5 V
16000 pF (Max) @ 0 V
80 nF (Typ.) @ 1 V
135 nF (Typ.) @ 0 V
Shunt Resistance - - 4 kΩ (Typ.) 2 kΩ (Min)
Package TO-5 Ceramic TO-8 Ceramic
Not Available STO8S
Not Available
  • Please note that the wire leads on the FDG05 and FDG10X10 are attached to the sensor using a conductive epoxy, as soldering them on would damage the sensor. This results in a fragile bond. Care should be taken while handing this unit so that the wire leads are not broken.
  • Typical Values; RL = 50 Ω
  • NEP is Specified for the Photovoltaic Mode
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
FDG03 Support Documentation
FDG03Ge Photodiode, 500 ns Rise Time, 800 - 1800 nm, Ø3 mm Active Area
FDG05 Support Documentation
FDG05Ge Photodiode, 220 ns Rise Time, 800 - 1800 nm, Ø5 mm Active Area
FDG50 Support Documentation
FDG50Ge Photodiode, 220 ns Rise Time, 800 - 1800 nm, Ø5 mm Active Area
FDG10X10 Support Documentation
FDG10X10NEW!Ge Photodiode, 10 μs Rise Time, 800 - 1800 nm, 10 mm x 10 mm Active Area

Dual Band Si/InGaAs Photodiode

  • Dual Detector Chip Design - Si Over InGaAs - Provides Wide Detector Range
  • 4-Pin TO-5 Package
  • Large Active Area
Item # Info Wavelength
Package Rise/Fall
DSD2 info 400 - 1100 nm
1000 - 1800 nm
5.07 mm2
(Ø2.54 mm, Si)
1.77 mm2
(Ø1.50 mm, InGaAs)
TO-5 4.0 µs
(Both Layers)
@ 0 V
1.9 x 10-14
2.1 x 10-13
1 nA @ 1 V
0.5 nA @ 1 V
450 pF @ 0 V
300 pF @ 0 V
  • Typical Values; RL = 50 Ω
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
DSD2 Support Documentation
DSD2Dual Band Si/InGaAs Detector, 4 µs Rise Time, 400 - 1700 nm, Ø2.54/Ø1.5 mm
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