Si Fiber-Coupled Amplified Photodetectors

  • Wavelength Range from 400 - 1000 nm
  • High Signal-to-Noise Ratio
  • Fixed or Switchable Gain Versions
  • Ultrafast up to 1.5 GHz


Fixed Gain
250 MHz Max Bandwidth




Switchable Gain
1500 MHz Max Bandwidth



Fixed Gain
600 MHz Max Bandwidth

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  • Detection of Fast Laser Pulses
  • Detection of Low Light Signals
  • Radio Frequency and Pulse Shape Extraction of Laser Light Sources
  • Heterodyne Laser Beat Signal Detection
  • Efficient Homodyne and Heterodyne Extraction of Optical Beat Signals
  • Detection of Low Light Signals
  • Characterization of Pulse Modulated Light Sources
  • Detection of Chopped Light Sources


  • Sensitive to Wavelengths from 400 nm to 1000 nm
  • Easy-to-Use, OEM Package with FC/PC Fiber-Coupled Input 
  • Integrated Low-Noise Amplifier
  • Power Supply Included

Menlo Systems' high-sensitivity Silicon (Si) PIN photodetectors are easy-to-use photodetectors with an integrated high-gain, low-noise RF (FPD310-FC-VIS) or transimpedance (FPD510-FC-VIS and FPD610-FC-VIS) amplifier. 

The FPD310-FC-VIS is optimized for high gain, high bandwidths, extremely short rise times, and high signal-to-noise ratio. The gain can be switched between two settings, which allows optimal performance for many applications. The 3 dB bandwidth of this AC-coupled device is 5 - 1000 MHz.

The FPD510-FC-VIS and FPD610-FC-VIS photodetectors are optimized for maximum signal-to-noise-ratio for detection of low-level optical beat signals and pulse shapes at frequencies up to 250 MHz and 600 MHz, respectively. Both detectors have a fixed gain. The FPD510-FC-VIS has a rise time of 2 ns, while the FPD610-FC-VIS has a 1 ns rise time. The 3 dB bandwidth of these DC-coupled devices is 200 MHz for the FPD510-FC-VIS and 500 MHz for the FPD610-FC-VIS.

The compact design of these detectors allows for easy OEM integration. These detectors feature a FC/PC input for fiber-coupled applications and include a power supply that has a universal AC input. To view Si detectors with free-space input, click here.

Optical Input FC/PC connector
Spectral Range 400 - 1000 nm
Saturation Limit <200 µW <100 µW <100 µW
Damage Threshold 2 mW 3 mW 3 mW
Detector Diameter 0.25 mm 0.25 mm 0.25 mm
Frequency Range 1 - 1500 MHz DC - 250 MHz DC - 600 MHz
3 dB Bandwidth 5 - 1000 MHz DC - 200 MHz DC - 500 MHz
Rise Time 0.5 ns 2 ns 1 ns
Gain (fs Pulsed Input)a Setting 1: 2 x 10Vpp/W
Setting 2: 2 x 103 Vpp/W
1.5 x 10Vpp/W 2 x 106 Vpp/W
Gain (CW Input)a Setting 1: 1.3 x 103 Vpp/W
Setting 2: 1.3 x 102 Vpp/W
2.5 x 104 Vpp/W 2.5 x 105 Vpp/W
Dark State Noise Level -100 dBm/Hz1/2 (up to 5 MHz)
 -130 dBm/Hz1/2 (5 to 1500 MHz)
-110 dBm/Hz1/2 (up to 5 MHz)
-135 dBm/Hz1/2 (5 to 250 MHz)
-80 dBm/Hz1/2 (up to 5 MHz)
-100 dBm/Hz1/2 (5 to 600 MHz)
NEP (calculated) 25.5 pW/Hz1/2 6.4 pW/Hz1/2 11.9 pW/Hz1/2
Output Impedance 50 Ω 50 Ω 50 Ω
Output Coupling AC DC DC
Output Signal ~1 V 0 to 1 V 0 to 1 V
Supply Voltage / Max. Current Consumption +12 VDC / 100 mA +12 VDC / 50 mA
-12 VDC / 20 mA
+5 VDC / <250 mA
-12 VDC / <50 mA
Typical Performance Graphs info info info
Output Connector SMA female
Operating Temperature 10 to 40 °C
Storage Temperature -20 to +85 °C
Storage Humidity (RH) 
10% to 90%
Device Dimensions 60 mm x 50 mm x 20 mm (2.4" x 2.0" x 0.79")
  • These detectors are optimized for femtosecond pulses within the specified frequency range. Gain will be approximately a factor of 10 lower for CW operation.

Signal Out- SMA Female (Photodetector)

BNC Female

For connection to a suitable monitoring device, e.g. oscilloscope or RF-spectrum-analyzer, with 50 Ω impedance.

Female (Power Cables)

Pinout for FPDPower Connector

Male Power IN (Photodetector)

Pinout for FPD Power Cable

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:
adarsh jain  (posted 2019-12-18 04:27:18.7)
Kindly let me know the min. average optical i/p power that can be detected faithfully with this detector.
asundararaj  (posted 2020-02-04 10:42:52.0)
Thank you for contacting Thorlabs. The minimum detectable power by detectors would depend on the NEP of the detector and the repetition rate of your laser.
ali.mirvakili  (posted 2013-01-30 17:13:05.57)
Hello, I have the PDA10A, but I need the photodetector which has higher bandwidth and also high gain; I came across the FPD310-FV and FDP510-FV; I could not see the transimpedance gain (V/A)in their spec compare to the spec of PDA10A; does it mean that these two detectors does not have the gain stage inside? My other question is related to this sentence given in the Overview of FPD310-FV:"This photodetector is not suitable for pulses longer than 30 ns or continuous light levels." I do need to test the pulses with the pulse width of 100 ns to 10 ns, so it means that this detector is not gonna work for me, right? Do you have any detector with the same bandwidth (around 1GHz)which also has a high gain of around 40dB? Thanks,
jlow  (posted 2013-02-06 16:26:00.0)
Response from Jeremy at Thorlabs: The gain is given at 750nm (which has a responsivity of about 0.5A/W). Therefore, the gain for setting 1 would be about 10^5 V/A and for setting 2 would be about 10^3 V/A. The FPD310-FV has a 3dB bandwidth of 10-900MHz, which is where the 30ns number come from. I will contact you directly to discuss about your application requirements.

Si Fiber-Coupled Amplified Photodetectors

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Metric Price Available
FPD310-FC-VIS Support Documentation
FPD310-FC-VISSi Switchable Gain, High Sensitivity PIN Amplified Detector, 400 to 1000 nm, 1 MHz - 1.5 GHz
FPD510-FC-VIS Support Documentation
FPD510-FC-VISSi Fixed Gain, High Sensitivity PIN Amplified Detector, 400 to 1000 nm, DC - 250 MHz
FPD610-FC-VIS Support Documentation
FPD610-FC-VISSi Fixed Gain, High Sensitivity PIN Amplified Detector, 400 to 1000 nm, DC - 600 MHz