400 kHz Photoreceivers LCA-S-400K


  • Si-PIN and InGaAs-PIN photodiodes
  • Wavelength range from 320 to 1700 nm
  • Bandwidth from DC to 400 kHz
  • Transimpedance gain  107 V/A
  • Min. NEP 75 fW/√Hz
Photodiode3.0 mm Ø Si-PIN0.5 mm Ø InGaAs-PIN
Spectral Range 320 – 1060 nm900 – 1700 nm
Bandwidth (-3 dB)DC – 400 kHzDC – 400 kHz
Rise/Fall Time (10% – 90%) 900 ns1 µs
Transimpedance 1 x 107 V/A1 x 107 V/A
Max. Conversion Gain 5.9 x 106 V/W (@ 920 nm)9.5 x 106 V/W (@ 1550 nm)
Min NEP (@ 10 kHz) 120 fW/√Hz (@ 920 nm)75 fW/√Hz (@ 1550 nm)

Output voltage ±10 V max (@ 1 MΩ load). Offset adjustable by trimpot. 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.

A new family of photoreceivers

By combining state of the art photodiodes with the proven and outstanding FEMTO LCA Current Amplifier technology we designed a new family of photoreceivers with a remarkable performance. The LCA-S-400K is available with either a large area Si or InGaAs photodiode covering a spectral range from 320 to 1060 nm and 900 to 1700 nm, respectively. The amplifier transimpedance is 107 V/A resulting in a maximum conversion gain of 9.5 x 106 V/W at 1550 nm for the InGaAs model.
Thanks to the very low-noise behavior of the transimpedance amplifier, the minimum NEP is only 75 fW/√Hz. This facilitates detection of optical signals in the 100 pW range without additional measures such as averaging or similar, and all this with a bandwidth of 400 kHz.

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.

All LCA-S 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. The optionally available adapter plate PRA-PAP opens up further mounting options.


  • Spectroscopy
  • General purposes opto-electronic measurements
  • Optical front-end for oscilloscopes, A/D converters and lock-in amplifiers

Related products / accessories

Power Supply


Post Adapter Plate