Features
- 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

Model | HSA-X-S-1G4-SI-FST HSA-X-S-1G4-SI-FC |
HSPR-X-I-1G4-SI-FST HSPR-X-I-1G4-SI-FC |
HSA-X-S-2G-IN-FST HSA-X-S-2G-IN-FC |
HSPR-X-I-2G-IN-FST HSPR-X-I-2G-IN-FC |
---|---|---|---|---|
Output | non-inverting | inverting | non-inverting | inverting |
Photodiode | Ø 0.4 mm Si-PIN | Ø 0.4 mm Si-PIN | Ø 0.1 mm InGaAs-PIN | Ø 0.1 mm InGaAs-PIN |
Spectral Range | 320 - 1000 nm | 320 - 1000 nm | 900 - 1700 nm | 900 - 1700 nm |
Bandwidth (−3 dB) | 10 kHz – 1.4 GHz | 10 kHz – 1.4 GHz | 10 kHz - 2 GHz | 10 kHz - 2 GHz |
Rise/Fall Time (10% - 90 %) | 250 ps | 250 ps | 180 ps | 180 ps |
Transimpedance | 5 x 103 V/A | 5 x 103 V/A inverting | 5 x 103 V/A | 5 x 103 V/A inverting |
Conversion Gain | 2.55 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 VSWR | 2.5 : 1 | 1.4 : 1 | 2.5 : 1 | 1.4 : 1 |
Maximum Output Voltage @ 50 Ω | 1,9 VPP | 2.0 VPP | 1,9 VPP | 2.0 VPP |
Output Noise | 3.6 mVRMS | 2.5 mVRMS | 3.6 mVRMS | 2.5 mVRMS |
Datasheet | ![]() |
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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.
Plugs and sockets
FEMTO amplifiers and photoreceivers are supplied with either a BNC or SMA socket as standard, depending on the model. We are happy to fit other plugs and sockets according to your requirements. In addition to BNC, SMA and type N, other types are also available on request. Simply add your request to your quotation enquiry or contact our support team.
Alternative plugs and sockets for photoreceivers are only possible on the signal output and monitor outputs without further ado. Alternative optical inputs are also not excluded but can only be realised as part of a custom-made product.
Due to their good properties at high frequencies, the GHz photoreceivers in the HSA-X-S and HSPR series have SMA sockets on the signal output as standard. The use of other sockets, such as BNC, is possible but may impair the signal quality.
Customised products
Do none of the products fulfil your requirements? We would be happy to offer you a customised product tailored to your application, which can also be implemented as an OEM version. Our technical support team looks forward to receiving your enquiry. You may also find something suitable among the related products.
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 fibre 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 fibre connections (FC, FSMA) easily by simply screwing on the fibre 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 fibre optic adapter. For models with detector areas smaller than Ø 0.4 mm, the use of fibre adapters is only recommended to a limited extent, since coupling losses and instabilities can occur. If the focus is on high-precision fibre optic measurements, using FC-models with fixed optical fibre 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.
Applications
- Spectroscopy
- Fast pulse and transient measurements
- Optical triggering
- Optical front-end (O/E converter) for oscilloscopes and A/D converters