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InGaAs Fiber-Coupled Amplified Photodetector


  • Wavelength Ranges Between 750 - 1650 nm
  • High Signal-to-Noise Ratio
  • Ultrafast up to 9.5 GHz
  • Fixed or Switchable Gain Versions

PDA8GS

Fixed Gain
9.5 GHz Max Bandwidth

FPD610-FC-NIR

Fixed Gain
600 MHz Max Bandwidth

 

FPD310-FC-NIR

Switchable Gain
1500 MHz Max Bandwidth

Related Items


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Applications

FPD310-FC-NIR FPD510-FC-NIR & FPD610-FC-NIR
  • 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
PDA8GS Application
Click to Enlarge

Application idea for the PDA8GS 9.5 GHz amplified photodetector.

Features

  • Built-in Amplifier
  • OEM Package with FC Bulkhead or Fiber-Coupled Module
  • Small Package Allows Easy Mounting
  • Minimum Recommended Load Resistor: 50 Ω
  • Power Supply Included

We offer a selection of Indium Gallium Arsenide (InGaAs) Fiber-Coupled Amplified Photodetectors that are sensitive to light in the NIR wavelength range. These fast response detectors are ideal for detection of fast laser pulses, low-light level signals, or chopped light sources. All detectors include a power supply.

PDA8GS
The PDA8GS is a versatile, high-speed, amplified photodetector designed to perform in a wide range of test and measurement applications involving fast optical signals. The unit incorporates a high-performance InGaAs PIN photodiode coupled with a transimpedance amplifier that has a gain of 460 V/A into 50 Ω with data rates up to 12.5 Gb/s. The wide bandwidth makes it ideal for evaluating pulsed laser and high-frequency modulation applications. Communication applications include 10 Gb Ethernet, OC192, and analog satellite microwave systems. This model exhibits linear performance across the input range, yielding low analog distortion. A 12 VDC, 750 mA power adapter is included with the PDA8GS. The housing features an FC bulkhead connector, which is compatible with both FC/PC and FC/APC connectors.

FPD310-FC-NIR
Menlo Systems' high-sensitivity, ultrafast PIN FPD310-FC-NIR photodetector is optimized for high gain, high bandwidths, extremely short rise times and high signal-to-noise ratio. The photodetector is an easy-to-use, InGaAs PIN photodiode with an integrated high-gain, low-noise, RF amplifier. The gain can be switched between two fixed settings, which allows optimal performance for many applications. The compact design of this detector allows for easy OEM integration. A low noise power supply with a universal AC input is included. This detector has an SMF28 Pigtail with an FC/APC optical input.

FPD510-FC-NIR & FPD610-FC-NIR
Menlo Systems' high-sensitivity, ultrafast PIN FPD510-FC-NIR and FPD610-FC-NIR 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. These photodetectors are easy-to-use, InGaAs PIN photodiodes with an integrated high-gain, low-noise transimpedance amplifier. The 3 dB bandwidth of these DC-coupled devices is 200 MHz for FPD510-FC-NIR and 500 MHz for FPD610-FC-NIR. The compact design of the detectors allows for easy OEM integration. A low noise power supply with a universal AC input is included with each. The detectors have an SMF28 Pigtail with an FC/APC optical input.

For InGaAs photodetectors with free-space input, click here.

Item # PDA8GS
Material InGaAs
Bandwidth DC - 9.5 GHz
Wavelength Range 750 - 1650 nm
Fiber Input 62.5 µm Core Multimode Fiber
Input Connectora FC Bulkhead
Output, 700 mV (Max)b SMA - 50 Ω
Peak Response, SM (Typ.) 0.95 A/W @ 1550 nm
Peak Response, MM (Typ.) 0.525 A/W @ 850 nm
Transimpedance Gain 460 V/A into 50 Ω
Max Optical Power (CW)b 1.0 mW
Max Peak Power (Pulsed)b 20 mWc
Rise Time <50 ps
Fall Time <50 ps
Dark Current -
NEP (Max) N/A
Junction Capacitance N/A
Housing Dimensions 3.0" x 2.38" x 1.1"
(76.2 mm x 60.45 mm x 27.94 mm) 
  • Compatible with both FC/PC and FC/APC connectors.
  • Damage to the photodiode may occur if these maximum ratings are exceeded.
  • Do not hold peak optical power for longer than a 60 ms burst.
Item # FPD310-FC-NIR FPD510-FC-NIR FPD610-FC-NIR
Material InGaAs
Optical Input SMF28 pigtail with FC/APC
Spectral Range 950 - 1650 nm
Saturation Limit <200 µW <100 µW <100 µW
Damage Threshold 2 mW 3 mW 3 mW
Frequency Range 1 - 1500 MHz DC - 250 MHz DC - 600 MHz
3dB Bandwidth 5 - 1000 MHz DC - 200 MHz DC - 500 MHz
Rise Time 0.5 ns 2 ns 1 ns
Gain Setting 1 2 x 10Vpp/W 1.5 x 10Vpp/W 2 x 106 Vpp/W
Gain Setting 2 2 x 103 Vpp/W
Dark State Noise Level
-100 dBm (up to 5 MHz)
-130 dBm (5 to 1500 MHz)
-110 dBm (up to 5 MHz)
-135 dBm (5 to 250 MHz)
-80 dBm (up to 5 MHz)
-100 dBm (5 to 600 MHz)
NEP (calculated) 12.0 pW/Hz1/2 3.0 pW/Hz1/2 5.6 pW/Hz1/2
Output Impedance 50 Ω 50 Ω 50 Ω
Output Coupling AC DC DC
Output Signal ~1 V 0 - 1 V 0 - 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")

PDA8GS

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.


FPD Series Detectors

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 FPD Power Cable

Male Power IN (Photodetector)

Pinout for FPDPower Connector

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. 

 

Equations:

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:
  and
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:
user  (posted 2019-05-09 13:43:00.173)
I have similar question that was posed to ThorLabs in past. Generally the detectors with GHz response have lower frequency cut-off of few 10s of kHz. Also AC coupled versions do not detect CW component. PDA8GS seems to be an exception. Can PDA8GS display DC and few kHz pulse trains (with pulses of slow rise /fall times few ns) without distortion? If a signal has DC and AC components, Can PDA8GS be used detect pulsed signal and its DC background (CW component)? Below is similar question from past from someone else for your ready reference. -Srikanth kedves (posted 2017-05-11 15:07:06.75) Dear Thorlabs, let me inquire about the frequency characteristics of PDA8GS. Is the transfer function over the whole frequency range DC-9.5 GHz smooth? I am asking this because we have fast amplified photoreceivers of another manufacturer which have a crossover region (at about 25-100 KHz) between the DC and AC responses leading to a distorted output signal to e.g. a step function input. What is the response of this detector to a step function? Is there any visible transition between the DC and high frequency ranges? Thanks nbayconich (posted 2017-06-07 05:03:14.0) Thank you for contacting Thorlabs. We are currently looking into measuring the bandwidth frequency characteristics of the PDA8GS. A techsupport representative will contact you directly with more information.
asundararaj  (posted 2019-05-09 07:27:47.0)
Thank you for contacting Thorlabs. The PDA8GS is a DC coupled detector and hence, it can detect both CW and and ~kHz pulsed components of the signal. I have contacted you directly via email to discuss this further.
minowa  (posted 2018-09-24 06:14:47.367)
Hi, could you provide the information about the NEP of PDA8GS?
YLohia  (posted 2018-09-24 01:17:12.0)
Hello, thank you for contacting Thorlabs. The dark current, at 25°C, is typically <10nA, and at 55°C is typically <50nA. The NEP for the fiber-optic receiver is: NEP (rms) 1.5uW typical @ 1310nm 3.0uW maximum @ 1310nm 2.5uW typical @ 850nm 5.0uW maximum @ 850nm Recently, we performed a preliminary test with 1550nm, and found that the input referred noise = 1.5uW rms (with 9.5GHz bandwidth). Assuming a white noise distribution over the 9.5GHz bandwidth, this implies NEP = 15pW/rt-Hz. These numbers then scale inversely with responsivity at other wavelengths. Please note that this only sample data and is not necessarily representative of our current units. These values presented are not a guaranteed performance.
kedves  (posted 2017-05-11 15:07:06.75)
Dear Thorlabs, let me inquire about the frequency characteristics of PDA8GS. Is the transfer function over the whole frequency range DC-9.5 GHz smooth? I am asking this because we have fast amplified photoreceivers of another manufacturer which have a crossover region (at about 25-100 KHz) between the DC and AC responses leading to a distorted output signal to e.g. a step function input. What is the response of this detector to a step function? Is there any visible transition between the DC and high frequency ranges? Thanks
nbayconich  (posted 2017-06-07 05:03:14.0)
Thank you for contacting Thorlabs. We are currently looking into measuring the bandwidth frequency characteristics of the PDA8GS. A techsupport representative will contact you directly with more information.
makarov  (posted 2016-05-26 14:11:44.267)
PDA8GS actually dies if the optical power rating is exceeded. This was a surprise to us. The maximum rating is 1 mW CW. We did not pay attention initially, because we thought the front-end photodied surely takes much more that 1 mW to get physically damaged, and what else could go wrong? It has turned out, the RF amplifier dies. Our units just came back from a lengthy and costly repair. I with it were stated in the spec sheet that damage to the RF amplifier will result from exceeding the optical power. We have similar amplified photodetectors from LeCroy (OE455/555) and they do not die from optical overload, even though they get saturated at less than 1 mW just as this Thorlabs photodetector.
besembeson  (posted 2016-06-01 05:33:43.0)
Response from Bweh at Thorlabs USA: This is actually a failure of the sensor material itself. To operate at these high speeds, the active area needs to be very small since the photodiode capacitance is directly correlated to active area. This is the limiting factor for electrical bandwidth. In this case, the fiber inserts against a ball lens that focuses all the light onto this very small active area sensor. The material damage threshold can easily be exceeded. Usually it looks like a very large dark current to the electronics where the gain is usually enough to saturate the output to the voltage rail. Since this is an integrated PD and amplifier package, the complete module needs to be replaced as a result of this - reason for the repair being more expensive than imagined.

InGaAs Fiber-Coupled Amplified Photodetectors

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
PDA8GS Support Documentation
PDA8GSInGaAs Fixed Gain Amplified Detector, 750 - 1650 nm, DC - 9.5 GHz
$4,512.43
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+1 Qty Docs Part Number - Metric Price Available
FPD310-FC-NIR Support Documentation
FPD310-FC-NIRInGaAs Switchable Gain, High Sensitivity PIN Amplified Detector, 950 - 1650 nm, 1 MHz - 1.5 GHz
$1,870.19
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FPD510-FC-NIR Support Documentation
FPD510-FC-NIRInGaAs Fixed Gain, High Sensitivity PIN Amplified Detector, 950 - 1650 nm, DC - 250 MHz
$1,870.19
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FPD610-FC-NIR Support Documentation
FPD610-FC-NIRInGaAs Fixed Gain, High Sensitivity PIN Amplified Detector, 950 - 1650 nm, DC - 600 MHz
$1,870.19
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