Intelligent vehicles, machines, and state-of-the-art devices move through an increasingly interconnected world more and more autonomously. Distance measurement and optical communication play a key role for them to be able to perceive their environment precisely and react accordingly. Avalanche photodiodes, short APDs, demonstrate their benefits as components in these cases and in many other applications.
Definition of APDs: Avalanche photodiodes are diodes with an internal gain mechanism. This gain mechanism allows them to recognize even low optical signal strengths and even individual photons.
Does your company implement measurement or communication solutions that must cope with low light levels? First Sensor is your experienced partner providing the matching APD for your challenge.
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Avalanche photodiodes are named that for a reason: The term avalanche refers to the internal APD gain – the so-called avalanche breakdown.
In standard diodes, impinging photons generate electron-hole pairs. These hole pairs provide a measurable photocurrent. In APDs, applied reverse bias voltage triggers an avalanche – it ensures that the electron-hole pairs are accelerated. The resulting impact ionization introduces further electrons to the conduction band. These electrons, in turn, absorb more energy and raise further electrons to the conduction band. This process is called avalanche breakdown and can thus achieve an avalanche multiplication factor of several hundred for the detector.
Avalanche photodiodes are faster and more sensitive than conventional photodiodes. Additionally, the spectral response of avalanche photodiodes is particularly high. Depending on the material, wavelengths of up to 1,700 nm can be achieved. First Sensor develops and manufactures avalanche photodiodes for different wavelengths subdivided into detector series.
With 650 nm to 850 nm for high cut-off frequencies, this avalanche photodiode is a perfect match for many devices and industrial applications such as laser scanning or optical communication.
Their enhanced near-infrared (NIR) sensitivity of up to 900 nm makes these avalanche diodes the ideal choice for LIDAR / LADAR applications. Light detection and ranging, short LIDAR, is a method for distance and speed measurement used in an increasing number of fields of mobility, e.g., in mobile speed control or for driver assistance systems.
These diodes detect wavelengths in a range from up to 1,064 nm and are thus particularly suited for long-wavelength ranges.
Material and processing can be tailored to your requirements. This allows the customization and optimization of specific parameters such as sensitivity in case of different wavelengths, speed of the APDs, and their capacity to your projects.
Spectral response
(T=typ. 23 °C, M=100)
Avalanche photodiodes allow precise and fast measurements especially when only low signal levels are available in optical communication or distance measurement.
APDs are also employed for applications with high modulation frequencies. As of frequencies of approx. 60 MHz, the noise level increased by the avalanche effect is generally lower than the noise level produced by a combination of a conventional photodiode with external gain electronics.
The typical applications of APDs thus include:
We will consult you individually to find the technology that will make your project successful. The following chart will provide you with an initial overview of the connection between the sensitivity of the avalanche photodiode and the wavelength with all photodiodes. Use your mouse to switch between the different products.
Road traffic is becoming safer, more efficient, and more autonomous. While driving, advanced driver assistance systems continuously check parameters such as the distance to the vehicle ahead, the speed limit but also obstacles on the road and other hazards. The use of optical distance and speed measurement will become indispensable in the future especially in self-driving or automated guided vehicles. The technology allows continuous monitoring of the surroundings from within the vehicle and makes sure that the lane is kept and hazards due to obstacles are avoided.
The systems usually installed as compact detector modules rely on safe, precise APDs featuring high NIR sensitivity. This requires know-how and industry competence. When avalanche diodes are operated outside of room temperatures in mobile applications, this can quickly lead to changes in the operating voltage and/or breakdown voltage, gain, dark current, sensitivity, capacitance, rise time, and total current.
First Sensor thus indicates the temperature coefficient and provides customers with comprehensive datasheets for each component. With our cross-industry experience, we will find the perfect solution for each customer project – for your application successfully becoming part of the mobility of the future.
Would you like to learn more about the varied perspectives the innovative, reliable and durable sensor solutions by First Sensor can offer you? Contact us!
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