First Sensor Unveils Avalanche Photodiodes for LIDAR applications

Posted Apr 16, 2018 by First Sensor

First Sensor AG has introduced new range of Series9 silicon avalanche photodiodes with very high sensitivity in the near infrared (NIR) wavelength range, especially at 905 nm.

Avalanche photodiodes (APD) are diodes with an internal gain mechanism. As in the case of standard diodes, photons generate electron-hole pairs, which are accelerated by the applied external voltage such that further electrons are introduced to the conduction band by means of impact ionization. These secondary electrons can in turn absorb sufficient energy to raise further electrons into the conduction band. A multiplication factor of several hundred can thus be achieved. The diodes are usually employed in the case of very low optical signal strengths, but are also used for applications with high modulation frequencies. As of frequencies of approx. 60 MHz, the noise level heightened by the avalanche effect is generally lower than that produced by a conventional diode in combination with external electronic amplification. Typical applications include distance measurement at low signal levels and optical communication. 

With their internal gain mechanism, large dynamic range and fast rise time the APDs are ideal for LIDAR systems for optical distance measurement and object recognition according to the time of flight method. Application examples include driver assistance systems, drones, safety laser scanners, 3D-mapping and robotics.

The Series9 offers detectors as single elements as well as linear and matrix arrays with multiple sensing elements. The package options include rugged TO housings or flat ceramic SMD packages. The slow increase of the gain of the Series 9 photodiodes with the applied reverse bias voltage allows for easy and precise adjustments of high gain factors. For particularly low light levels, hybrid solutions are also available that further enhance the APD signal with an internal transimpedance amplifier (TIA). The integrated amplifier is optimally matched to the photodiode and allows compact setups as well as very large signal-to-noise ratios.

Thanks to its own semiconductor manufacturing facility and extensive development capabilities, First Sensor can adapt its silicon avalanche photodiodes to specific customer requirements, e.g. in terms of sensitivity, gain, rise time or design.

Important features of the Series 9 APDs Include:

  • Very high sensitivity at 905 nm
  • Large dynamic range and fast rise time
  • Single element photodiodes as well as linear and matrix arrays
  • Rugged TO housings or flat ceramic SMD packages
  • Hybrid solutions with integrated TIA