Physicists propose a new way to detect infrared radiation
Recently, physicists at the Federal Institute of Technology in Lausanne (EPFL) have proposed a new method of detecting infrared radiation, which is highly sensitive and can even detect single photon signals. A nanoscale solution based on a molecular optomechanics platform to upconvert terahertz and mid-infrared (MIR) photons to the visible-near-infrared (VIS-NIR) band and add noise to them using a full quantum model and conversion efficiency were analyzed in detail. The research titled "Molecular platform for frequency upconversion at the single-photon level" was published in physics.optics, and the address of the paper is: https://arxiv.org/abs/1910.11395v1.
When using webcams or cell phone cameras, we experience the power of cheap, compact sensors developed over the past few decades for the visible region of the electromagnetic spectrum. In contrast, detecting low-frequency radiation that is invisible to the naked eye, such as mid- and far-infrared radiation, requires complex and expensive equipment. Sensors for molecular recognition and imaging of heat radiation naturally emitted by the human body are not yet widely available due to a lack of compact technology. Therefore, new conceptual breakthroughs in this area could have a huge impact on our daily lives. Direct detection of single photons with wavelengths greater than 2 micrometers under ambient conditions is currently still a serious technical challenge.
Currently the most popular technique for detecting mid-to-far infrared radiation is the microbolometer, which consists of an array of small thermometers that measure the heat generated by absorbed radiation. Such detectors have a number of limitations, notably slow response times and the inability to detect faint radiation signals.
The EPFL team led by Christophe Galland and Tobias Kippenberg has proposed a new detection method that follows a completely different path: first converting the invisible radiation into visible light and then detecting it with existing technologies. At the heart of this new concept are hybrid metal-molecular nanostructures. The metal is modified to focus infrared radiation on the molecules, causing them to vibrate. The energy of the vibrating molecules is then converted into radiation again, but this time as visible light. This hybrid nanostructure, designed in collaboration with Diego Martin-Cano (Max Planck Institute for Light, Erlangen, Germany), achieves high conversion efficiencies while shrinking the devices to sizes much smaller than the wavelength of infrared light.
