GHz-Photorecevers HSPR-X and HSA-X-S


  • Si-PIN and InGaAs-PIN photodiodes
  • Wavelength range from 320 to 1700 nm
  • Ultra-wide bandwidth from 10 kHz up to 2 GHz
  • Max. conversion gain 4.75 x 103 V/W
  • Min. NEP 11 pW/√Hz
Output Performancenon-invertinginvertingnon-invertinginverting
PhotodiodeØ 0.4 mm Si-PINØ 0.4 mm Si-PINØ 0.1 mm InGaAs-PINØ 0.1 mm InGaAs-PIN
Spectral Range320 – 1000 nm320 – 1000 nm900 – 1700 nm900 – 1700 nm
Bandwidth (−3 dB)10 kHz – 1.4 GHz10 kHz – 1.4 GHz10 kHz – 2 GHz10 kHz – 2 GHz
Rise/Fall Time
(10 % – 90 %)
250 ps250 ps180 ps180 ps
Transimpedance5 x 103 V/A5 x 103 V/A
5 x 103 V/A5 x 103 V/A
Conversion Gain2.55 x 103 V/W
(@ 760 nm)
2.55 x 103 V/W
(@ 760 nm)
4.75 x 103 V/W
(@ 1550 nm)
4.75 x 103 V/W
(@ 1550 nm)
NEP (@ 100 MHz)32 pW/√Hz
(@ 760 nm)
19 pW/√Hz
(@ 760 nm)
16 pW/√Hz
(@ 1550 nm)
11 pW/√Hz
(@ 1550 nm)
Output VSWR2.5 : 11.4 : 12.5 : 11.4 : 1
Maximum Output Voltage @ 50 Ω1,9 VPP2.0 VPP1,9 VPP2.0 VPP
Output Noise3.6 mVRMS2.5 mVRMS3.6 mVRMS2.5 mVRMS

Output short-circuit protected. Threaded M4 and 8-32 mounting holes for use with standard mounting posts. Power supply +15 V via 3-pin Lemo® socket. A mating connector is provided with the device. Optional power supply PS-15 available. For further information please view the datasheet or contact FEMTO.

GHz technology

By combining state of the art photodiodes with the proven and outstanding FEMTO GHz amplifier technology we designed a new family of photoreceivers with a remarkable performance. The HSPR-X and HSA-X-S offer an upper bandwidth limit of 2 GHz. Two models with either a fast Si-PIN or InGaAs-PIN photodiode cover a spectral range from 320 to 1000 nm and 900 to 1700 nm, respectively. Due to the sophisticated amplifier design the minimum NEP is just 11 pW/√Hz at a transimpedance of 5 x 103 V/A. This allows for the measurement of optical power levels in the µW range with GHz speed.

Compatible with optical bench (free space) and fiber optics

The free space input (FST) is designed as a 1.035″-40 threaded flange with a screw-on coupler ring. It opens up a broad compatibility with optical accessories from various manufacturers, such as lenses, tubes, cage systems, optical adapters etc.

The free-space input can be converted into fiber connections (FC, FSMA) easily by simply screwing on the fiber adapter of the PRA series.

The relatively large-area detector facilitates optical focusing in free-space applications and ensures a high and stable degree of coupling when using the optionally available fiber optic adapter. For models with detector areas smaller than Ø 0.4 mm, the use of fiber adapters is only recommended to a limited extent, since coupling losses and instabilities can occur. If the focus is on high-precision fiber optic measurements, using FC-models with fixed optical fiber input will usually give the best results.

All HSA-X-S and HSPR-X photo receivers are equipped with UNC 8-32 and M4 threaded holes and can therefore be conveniently and stably integrated into optical systems on standard rod holders.


  • Spectroscopy
  • Fast pulse and transient measurements
  • Optical triggering
  • Optical front-end (O/E converter) for oscilloscopes and A/D converters

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