Photon Force cameras and sensors containing SPAD arrays

 

A SPAD array, or Single-Photon Avalanche Diode array, is a highly sensitive optical sensor designed to detect and count and time the arrival of single photons.

These detectors are important in fields where the light levels are so low that conventional detectors won’t work. But how exactly does a SPAD sensor work, and what are its applications? In this blog, we’ll break down everything you need to know about SPAD arrays, from their functionality to their cutting-edge uses in research and industry.

How Does a SPAD Sensor Work?

SPADs (Single-Photon Avalanche Diodes) are semiconductor devices designed to detect individual photons. When a photon hits a SPAD sensor, it triggers an avalanche effect in the diode, causing a sudden surge of current. This avalanche is then detected by electronics, which register the presence of a single photon.

In a SPAD array, multiple SPAD detectors are integrated into a grid-like structure. This configuration allows the device to capture photons across a wider field, making it perfect for imaging applications. Each element in the SPAD array works independently, meaning it can register, count and time the arrival photons simultaneously across the entire sensor.

The ability to detect, count and time the arrival of single photons in real-time is what makes SPAD arrays stand out, particularly in Time-Correlated Single Photon Counting (TCSPC) applications. TCSPC is a technique used to measure the arrival time of photons relative to a periodic synchronisation (normally from a laser), offering highly accurate time of flight measurements. This functionality is essential in applications ranging from medical imaging to 3D LiDAR mapping.

How are SPAD Detector Arrays used?

SPAD detector arrays are used in a variety of applications that require precise photon detection, counting and timing. Some of the key areas where SPAD arrays excel include:

1. Time-Resolved Fluorescence Microscopy

SPAD arrays are ideal for time-resolved fluorescence microscopy, a technique used in biological sciences to study cellular and molecular processes in real-time. Because of their single-photon sensitivity and timing capabilities, SPAD arrays can capture fluorescence decay times with incredible accuracy, enabling researchers to gather detailed insights into biological mechanisms.

2. LiDAR and 3D Mapping

SPAD arrays are commonly used in Light Detection and Ranging (LiDAR) systems to produce high-resolution 3D maps. In LiDAR, pulses of laser light are emitted, and the time it takes for these pulses to return to the detector is measured. Since SPAD arrays are highly sensitive to single photons, they can detect even the faintest reflections, making them ideal for creating detailed, accurate maps – particularly in low-light environments.

3. Quantum Cryptography and Quantum Optics

SPAD arrays play a critical role in both quantum cryptography and quantum optics, two fields at the cutting edge of modern science. In quantum cryptography, SPAD arrays are used to detect and measure individual photons, which are the carriers of quantum keys in secure communication systems. This ensures that data transmissions are protected by the fundamental principles of quantum mechanics, making it impossible for any eavesdroppers to intercept messages without detection.

In quantum optics, SPAD arrays are used to study and manipulate light at the quantum level, helping researchers explore phenomena such as entanglement, superposition and photon interference. Their single-photon sensitivity is essential for experiments that require precise photon counting and timing, making SPAD arrays indispensable tools within quantum science and technology.

By supporting both secure communications and fundamental research, SPAD arrays are central to advancements in quantum information processing and the broader field of quantum technologies.

4. Medical Imaging and Diagnostics

SPAD detector arrays are also used in medical imaging applications like positron emission tomography (PET) and fluorescence lifetime imaging microscopy (FLIM). Their ability to capture precise photon information makes them invaluable for producing detailed, high-contrast images, which are essential for accurate diagnostics and research.

What is the difference between SPAD Arrays and Traditional Sensors?

Compared to traditional optical sensors, SPAD arrays offer several advantages:

  • Higher Sensitivity: SPADs can detect single photons, making them far more sensitive than traditional detectors like CMOS cameras or charge-coupled devices (CCDs), which require a much higher intensity of light to register a signal.
  • Picosecond accuracy timing: SPAD arrays from Photon Force offer the ability to time the arrival of single photons with picosecond accuracy. Conventional sensors cannot offer this capability.
  • High-Speed Detection: The PF32 range from Photon Force allows for ultra-high frame rates – up to 700kfps! This speed, coupled with single photon sensitivity is vital for applications such as diffuse correlation spectroscopy (DCS).

Why Photon Force knows so much about SPAD Arrays

Photon Force is a leading provider of SPAD array solutions, offering products that facilitate advancement in single-photon detection and imaging technology. Our flagship product range, the PF32 camera series, is designed specifically for high-performance single-photon counting and timing applications. The PF32 cameras incorporate state-of-the-art SPAD arrays, offering users exceptional sensitivity and precision for time-resolved measurements.

In addition to the PF32 range, Photon Force specialises in designing and manufacturing custom SPAD sensors for OEM applications. Whether your project requires a tailored solution for a specific photon detection challenge or you need a high-performance sensor for a research application, our team can work with you to create the perfect fit.

Our SPAD-based products are trusted across industries, from academic research to advanced manufacturing, helping innovators leverage the power of single-photon detection and counting for their most challenging projects.

Conclusion

SPAD arrays are an essential photon detection technology, offering unparalleled sensitivity, speed and precision for a wide range of applications. Whether it’s time-resolved imaging, quantum cryptography or LIDAR, SPAD detector arrays are a key tool in modern optical sensing. With products like the PF32 camera range and custom OEM solutions, Photon Force is helping researchers and engineers tap into the full potential of SPAD arrays to achieve breakthroughs in their fields.

For more information on how Photon Force’s SPAD array solutions can support your project, contact us today.