Overcoming the Technical Challenges of Single Photon Detection
Our natural desire to better understand the behavior in the world around us brought us the research field of quantum optics — the study of nature and effects of light as quantized photons. The rapidly evolving world of quantum optics has created a demand for a new generation of high performance detectors that can accurately and efficiently detect light signals down to the single photon.
These detectors are essential for applications and research fields such as: High-End LIDAR, Quantum Optics, Quantum Telecommunications, High Energy Physics, Particle Physics, Nuclear Physics, Fluorescence Imaging, Astronomy, Plasma Research and many others. The ability to detect individual photons with high precision and efficiency is paramount for advancing these fields.
The Need for Single Photon Detection Technology
Single photon detection and imaging technologies are an area of intense and continuing interest. The rapidly evolving field of research represents the bridge between our daily experience within the visible light spectrum and the quantum realm, where we may access low-level light signals down to the singular photon.
Applications such as those mentioned above present strict engineering requirements, such as high photon detection efficiency, low dark-count rate, sensitivity in the IR-spectrum, and instrument-limited time jitter. The many applications and their requirements have together motivated research and development efforts for single-photon detectors.
Common types of single-photon detection technologies include Avalanche Photodiodes (APDs), InGaAs/InP & Silicon Single Photon Avalanche Diodes (SPADs), Transition-Edge Sensors, Single Electron Transistor Detectors (SET), Superconducting Nanowire Single Photon Detectors (SNSPDs), and Vacuum Tube-Based Photon Detectors. While many types of detectors exist, vacuum tube-detectors set themselves apart with their ability to operate in a wide range of temperature conditions, their high detection efficiency, and their relatively inexpensive pricing.
Vacuum Tube Detectors: How They Work
Vacuum tube-based Image Intensifier Tubes are best known for their use in night vision goggles used in military applications. The same technology can also be used to build highly sensitive detection solutions for low light level imaging and single photon counting.
Vacuum tube-based Image Intensifier tubes consist of several essential components; a Photocathode, a Microchannel Plate (MCP) and an anode. These components work together to amplify input signal, creating a rich and dynamic output.
In the first step, existing ambient light passes through a photocathode, which converts the incoming photon signal into a photo-electron.
In the second step, photoelectrons are drawn by an electrical field into the MCP where they impinge multiple times on the inner walls and thereby multiply several thousands of times. For photon counting applications the multiplied electron signal is detected using an anode. In the instance of photon imaging applications, the anode converts the electron back into photons to produce an image.
To further visualize how an image intensifier tube works, click the link to watch a video demonstration of Cricket™2 an advanced image intensifier adapter for single photon and low light level imaging.
Vacuum Tube Detector Benefits
A major benefit of vacuum tube-based, single photon detectors is their high detection efficiency. The properties of the thin photosensitive layer (photocathode) inside the vacuum enable extremely low dark count rates combined with market leading quantum efficiency.
The quality of the vacuum and parts in the vacuum make after-pulsing nearly non-existent. This results in high detection efficiency of single photons, which makes it possible to detect and measure extremely weak light signals.
An additional benefit of vacuum tube-based photon detectors is their low noise operation. The gated mode of operation (extreme fast electronic shutter) enables the photocathode to be active only for a short period of time, reducing the number of false counts generated by dark counts and after pulsing. This makes it possible to accurately detect and measure weak light signals in a wide range of scientific and industrial applications.
Reliability and Lifetime
An advantage of vacuum tube-based, single-photon detectors is their ability to operate within a wide range of temperatures and in extreme environments. The Extreme High Vacuum (XHV) inside the tube helps to protect the photocathode from damage, which results in an extended lifetime of the detector. This makes these detectors an ideal choice for use in harsh environments and for long-term measurements.
In addition to performance benefits, vacuum tube-based, single-photon detectors can be relatively less expensive to produce than other types of single-photon detectors. Their long lifetime benefits coupled with their low cost make vacuum tube-based detectors an ideal candidate for single-photon detection and imaging techniques. As such, these detectors are more accessible to a wide range of users and in a variety of applications.
The Photonis Solution
Photonis offers state-of-the-art vacuum tube detector technology, delivering advanced solutions for a new generation of high-performance photon detectors. Their use in Quantum Optics allows us to “Reveal the Invisible” in the world around us!
The company proposed various types of high-sensitivity, fast-timing, low-noise, vacuum tube-based, single-photon detectors for OEM and end-user applications. Their team of experts provides support and consulting services to help select and implement the right single-photon detector for all applications, from Space to Quantum Telecommunications and many others.
The multi-alkali, Hi-QE photocathode technology from Photonis combines a high quantum efficiency (QE) in the 120–1050 nm spectral range, with a dark count rate as low as 50 Hz/cm², thereby achieving a superb signal-to-noise ratio. When the photocathode is utilized as an ultra-fast, electro-optical shutter, sub-nanosecond (billionth of a second) gating speeds can be achieved for accurate transient phenomena imaging.
To request more information or a quotation for any Photonis products, contact IL Photonics.