An international team of researchers has developed a mid-infrared spectrometer with a diameter smaller than a human hair,media reported. Mid-infrared spectrometers could be used for greenhouse gas detection and could make self-driving cars safer. Therefore, in recent years, there has been great interest in developing compact on-chip spectrometers. Whereas traditional spectrometers are bulky and expensive, on-chip spectrometers can greatly expand the application and accessibility of this technology.
To achieve this goal, a team of researchers from the United States, Israel and Japan has developed an ultra-compact mid-infrared spectrometer. The research was led by Fengnian Xia, Associate Professor Barton L. Weller, Yale School of Engineering and Science, Professor Doron Naveh, Bar-Ilan University, Israel, and Kenji Watanabe and Takashi, National Institute for Materials Science, Japan. Taniguchi collaborated.
(Image credit: Yale University)
The spectrometer uses black phosphorus (BP), a material long studied in Fengnian Xia’s lab, allowing it to operate in the 2 to 9 micrometer wavelength range based on a single tunable photodetector. Black phosphorus, which is about 10 nanometers thick, allows users to tune the interaction of light and matter to capture different spectral components, which is key to the device’s success. In addition, advanced algorithms are important to the spectrometer, which can transfer some of the inherent complexity in spectroscopy from hardware to software.
The spectrometer measures 9 x 16 square microns, much smaller than the cross-section of a human hair, and comparable in size to the wavelengths of light it measures. Even if spectrometers get smaller, their performance won’t improve much due to diffraction, because light typically cannot be concentrated at points much smaller than its wavelength.
Professor Doron Naveh from Bar-Ilan University said: “We are very pleased to have developed this compact and high-performance spectrometer. We hope that the principles of hardware and software development in this work can be used to advance applications in medicine, agriculture and food quality control. commercial applications in the field.”
Traditional spectrometers separate light into the colors that make up the spectrum. “The new spectrometer has advantages over traditional light-splitting spectrometers because light does not need to be spatially separated into different parts,” said Shaofan Yuan, a doctoral student in Fengnian Xia’s lab and lead author of the study.
Unlike conventional spectrometers, the system does not rely on advanced optical components such as interferometers or tunable infrared lasers, thus potentially minimizing spectrometer size and enabling on-chip, economical mid-IR spectroscopy and spectral imaging. Cars, drones and satellites are often equipped with infrared cameras that can take grayscale thermal images to detect pedestrians, vehicles and other hazards, the researchers noted. The spectrometer in Fengnian Xia’s lab is highly capable of detecting such potential threats, so it can continuously measure spectral information, albeit with insufficient resolution. In addition, the spectrometer can also be used for remote sensing.