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FWPR-20 Series

  • Ultra-Low-Noise – Min. NEP 0.7 fW/√Hz allows direct detection down to 50fW
  • Transimpedance Amplifier with High Gain up to 1012 V/A Included
  • Wavelength Range from 320 nm to 1700 nm

Ultra-High Sensitivity and Very Low Noise Photoreceiver

The series FWPR-20 Photoreceivers combine low-noise Si or InGaAs photodiodes with a specially designed transimpedance amplifier with extremely high gain of up to 1012 V/A and very low noise. This unique combination results in a photoreceiver with Femtowatt sensitivity due to its exceptional low NEP of minimum 0.7 fW/√Hz. Direct detection of optical powers down to ca. 50 fW is possible and when combined with an optional FEMTO Lock-In Amplifier even sub-Femtowatt sensitivity can be achieved.

Post holder and post not included

Replace your expensive APD, PMT or LN2 cooled IR Detector

Due to their very high sensitivity the FEMTO FWPR-20 series photoreceivers can replace APDs, PMTs and cooled Ge photodiodes in many applications. No expensive high voltage power supply or cooling is required.

The FWPR-20-SI offers high quantum efficiency in the visible and near infrared similar to that of APD based single photon counting modules. In applications where timing is uncritical, e.g. when the signal of a photon counter is integrated for a few 10 ms or more the FWPR-20-SI photoreceiver achieves a comparable signal-to-noise ratio.

For NIR spectroscopy the InGaAs model FWPR-20-IN achieves similar results as a much more expensive and complex system based on a liquid nitrogen cooled Germanium detector with external amplifier. As a result of the already integrated verylow-noise high-gain amplifier signals in the Volt range can be achieved directly at the output of the series FWPR-20 Femtowatt Photoreceiver.


  • Fluorescence Measurements
  • Spectroscopy
  • Electrophoresis
  • Chromatography
  • Replacement for Photomultiplier Tubes (PMTs), Avalanche Photodiodes (APDs) and Liquid Nitrogen Cooled Germanium Photodiodes
Spectral Range320 ... 1100 nm900 ... 1700 nm
Bandwidth (-3 dB)DC ... 20 HzDC ... 20 Hz
Photodiode1.1 x 1.1 mm2 Si0.5 mm Ø InGaAs PIN
Rise Time (10% - 90%)18 ms18 ms
Transimpedance Gain1 x 1012 V/A1 x 1011V/A
Max. Conversion Gain0.6 x 1012 V/W (@ 960 nm)0.95 x 1011 V/W (@ 1550 nm)
Min NEP0.7 fW/√Hz (@ 960 nm)7.5 fW/√Hz (@ 1550 nm)
Saturation Power18pW (@ 960mm)110 pW (@ 1550mm)
DetectorSi, 1.1 x 1.1 mm2InGaAs PIN, Ø0.5 mm
InputFree space, 25 mm Ø Flange
Output Voltage Range± 10 V @ > 1 MΩ Load
Power Requirements±15 V, ±15 mA Typ.
Threaded M4 and 8-32 holes for mounting on standard posts. 25 mm Ø flange compatible with microbench systems. Offset adjustable by trimpot. Fiber optic input optional. Output short-circuit protected. Power supply via 3-pin LEMO socket. A mating connector is provided with the device. Optional power supply PS-15 is available. For further information please view the datasheet.

FEMTO Product Catalog 

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