Brief description
The BSI photodetectors consist of black-silicon photodiodes and a fixed-gain transimpedance amplifier. They are optimised for maximum gain at a bandwidth of up to 20 MHz.
Thanks to black silicon technology, the BSI photodetectors offer 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 suffer significant losses in sensitivity.
Features
- Bandwidth DC up to 20 MHz
- Transimpedance Gain up to 107 V/A
- NEP down to 110 fW/√Hz
- Black silicon photodiodes with 1 mm by 1 mm2 or 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
| Model | LCA-S-400K-BSI-FST | HCA-S-20M-BSI-FST |
|---|---|---|
| Black Silicon Photodiode | 2 × 2 mm² | 1 x 1 mm² |
| Spectral Range | 200 - 1100 nm | 200 - 1100 nm |
| Bandwidth (−3 dB) | DC - 400 kHz | DC - 20 MHz |
| Rise Time (10 - 90 %) |
900 ns | 18 ns |
| Transimpedance Gain | 1 × 107 V/A | 1 × 105 V/A |
| Conversion Gain | 7.3 × 106 V/W | 7.3 × 104 V/W |
| NEP | 110 fW/√Hz | 3.3 pW/√Hz |
| Output Voltage | -3 - +10 V | ± 1.5 V |
| Signal output | designed for high-impedance load, to be terminated with ≥ 100 kΩ | Designed for 50 Ω load, to be terminated with 50 Ω; |
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Offset adjustable by potentiometer. Output short-circuit protected. Power supply 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.
Cable recommendation
For detailed information on which cable we recommend for which application and why, please see our Cable Selection Guide.| Recommended FEMTO cable | Why? | |
|---|---|---|
| Output | RF cable | Focus on maximum EM shielding and/or 50 Ω impedance matching |
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. It is approximately 90% 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 almost constant even in the deep UV. This makes black silicon photodetectors 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, black silicon photodetectors 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 black silicon photodetectors operate at room temperature and do not require cooling, as is necessary for example with germanium photodiodes or some APDs. This significantly simplifies usage and enables compact measurement setups.
Comparison: Black Silicon vs. default Si-PIN
| Photodiode | Black silicon | Standard Si-PIN | Spectral Range | 200 - 1100 nm | 320 - 1060 nm |
|---|---|---|
| Quantum Efficiency (UV) | approx. 90 % @ 250 nm | < 65 % @ 250 nm |
| Quantum Efficiency (VIS) | approx. 90 % | approx. 80-90 % |
| Angular Dependency | no (up to approx. 70°) | Yes |
| UV Sensitivity | outstanding | limited |
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.
Customised products
Do none of the products fulfil your requirements? We offer customer-specific versions of our products, e.g. adapted bandwidth, amplification or optimisation for special signal sources. OEM versions, for example for larger projects and product integrations, are also possible. Our technical support team looks forward to your enquiry. You may also find something suitable among the related products.
| Model | HBPR-100M-60K-IN-FST HBPR-100M-60K-IN-FS HBPR-100M-60K-IN-FC |
|---|---|
| 10 mW on each photo diode | |
| Low Pass Filter | Full bandwidth switchable to 20 MHz (upper cut-off frequency) |
| High pass filter (AC coupling) | DC coupling switchable to AC (10 Hz lower cut-off frequency) |
| Signal output voltage | ±1.0 V at 50 Ω load (for linear gain and low harmonic distortion), maximum ±2.0 V at 50 Ω load |
| Monitor outputs | transimpedance gain 1000 V/A, bandwidth DC - 10 MHz, output voltage 0 ... +10 V (@ ≥100 kΩ load) |
| Supply voltage / Supply current | ±15 V (±14.5 V ... ±16.5 V) -90 / +120 mA typ. |
| Case | 80 x 80 x 30.5 mm (L x W x H) Weight FC models 350 g (0.77 lbs), weight FS/FST models 410 g (0.9 lbs) |
Compatible with optical bench (free space) and fibre optics
The free space input (FST) is designed as 1.035″-40 threaded flange with 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 relatively large-area detector facilitates focusing in free space applications and ensures high and stable coupling efficiency even when using the optionally available fibre optic adapters.
The LCA-S-400K-BSI can easily be converted to a fibre connection (FC, FSMA) thanks to the large detector surface, by simply screwing on optionally available fibre adapters of the PRA series.
It is equipped with UNC 8-32 and M4 threaded holes and can therefore be conveniently and stably integrated into optical systems on standard holders.
Applications
- Spectroscopy (UV-VIS-NIR)
- Fluorescence measurements
- Chromatography
- Reflection and transmission measurements
- Time-resolved optical pulse and power measurements
- Characterisation of light sources (including UV LEDs and broadband sources)
- High-sensitivity measurements using chopper modulation
- Optical input module (O/E converter) for oscilloscopes, A/D converters, and lock-in amplifiers
- UV radiation measurement technology and environmental monitoring
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