With the LCA-S-400K-BSI, FEMTO offers its first photodetector featuring a 2 × 2 mm² black silicon photodiode. Black silicon photodiodes exhibit near-ideal light sensitivity in the wavelength range from 200 nm to 950 nm, with a quantum efficiency of 90 % or higher across most of the usable optical spectrum.
The LCA-S-400K-BSI features a bandwidth from DC to 400 kHz and a transimpedance gain of 107 V/A. The NEP is 110 fW/√Hz.
Full details including detailed specifications here.
Brief description
The LCA-S-400K-BSI photodetector consists of a black-silicon photodiode and a fixed-gain transimpedance amplifier. It is optimised for maximum gain at a bandwidth of 400 kHz.
Thanks to black silicon technology, the LCA-S-400K-BSI offers exceptionally high quantum efficiency of approximately 90% across a very broad spectral range from 240 to 1000 nm-including the deep UV range starting at 200 nm, where conventional silicon photodiodes exhibit significant losses in sensitivity.
Features
- Bandwidth DC - 400 kHz
- Transimpedance Gain 107 V/A
- NEP 110 fW/√Hz
- Black silicon photodiode with 2 × 2 mm2 active area
- Spectral range 200 - 1100 nm with approx. 90 % quantum efficiency from 240 - 1000 nm
- Freespace input with 1.035”-40 thread, compatible with most optical standard equipment
- Fibre connection is easily achievable using PRA series adapters
Technology: Black Silicon Photodiodes
Black silicon is a semiconductor material whose surface is modified with micro- and nanostructures in such a way that incident light is almost completely absorbed. The characteristic deep black appearance results from the nanoscale texturing of the silicon surface, which minimises reflection losses. While conventional polished silicon reflects up to 40% of incident light depending on the wavelength, the reflectance of black silicon is typically below 1% over a broad spectral range.
Near-ideal quantum efficiency over an ultra-broad spectral range
The main advantage of black silicon photodiodes lies in their exceptional quantum efficiency. The LCA-S-400K-BSI achieves approximately 90% quantum efficiency in the range from 240 to 1000 nm. In contrast to conventional Si PIN photodiodes, whose sensitivity drops significantly in the UV range due to reflection and recombination losses, the sensitivity of black silicon diodes remains nearly constant even in the deep UV. This makes the LCA-S-400K-BSI particularly suitable for applications requiring uniform spectral sensitivity over a wide wavelength range.
Excellent UV sensitivity
Conventional silicon photodiodes exhibit significant sensitivity losses in the UV range (below 350 nm), caused by high surface reflection and recombination of charge carriers generated near the surface. The nanostructured surface of black silicon diodes almost completely eliminates reflection losses, while the induced junction ensures efficient collection of UV-generated charge carriers. This eliminates the need for special UV coatings or separate UV-optimised detectors.
Wide angular acceptance
The nanostructured surface ensures low reflection even at high angles of incidence. Typical black silicon photodiodes provide reliable response at angles of incidence up to 70°, representing significantly greater angular tolerance compared to planar detectors with anti-reflection coatings. This simplifies optical setups and reduces alignment effort.
Replacement for multiple detectors
Due to the ultra-broad spectral range from 200 to 1100 nm, the LCA-S-400K-BSI can simplify measurement setups that previously required multiple detectors for UV, VIS, and NIR. A single black silicon photodetector can cover the entire range, reducing cost, complexity, and calibration effort.
No additional cooling required
The LCA-S-400K-BSI operates at room temperature and does not require cooling, as is necessary for example with germanium photodiodes or some APDs. This significantly simplifies usage and enables compact measurement setups.