For decades, scientists have sung the praises of lasers and their abilities for observing, detecting, and measuring element in the natural world that are too small for the human eye. The challenge has always been that lasers are expensive and large, making their usage difficult in many situations.
In a study published in the journal Science by Qiushi Guo, PhD, assistant professor at the City University of New York (CUNY) Graduate Center Advanced Science Research Center’s Photonics Initiative and a physics professor at the CUNY Graduate Center, establishes a novel approach for creating high-performance ultrafast lasers on nanophotonic chips, which can be used in multiple sectors, including in the food safety environment.
His work centers on miniaturizing the mode-lock laser, which he describes as “a unique laser that emits a train of ultrashort, coherent light pulses in femtosecond intervals,” equivalent to a quadrillionth of a second. His research leverages an emerging material platform known as thin-film lithium niobate (TFLN), which allows for efficient shaping and precise control of laser pulses by applying an external radio frequency electrical signal.
Thanks to its compact size, it could mean that these ultrafast mode-locked lasers could one day allow for cell phones to diagnose eye diseases or environments to be analyzed for E. coli and other pathogens.
“Revealing the intricacies of unknown substances and understanding their chemical composition necessitates a powerful tool: infrared absorption spectroscopy,” Dr. Guo tells Food Quality & Safety. “This technique has the capacity to sensitively detect highly characteristic rotational or vibrational transition bands exhibited by a diverse range of molecules and functional groups, i.e. the ‘fingerprints’ of various chemicals.”
He says that when integrated with a nonlinear optical spectral broadening element and a photodetector, the chip-scale mode-locked laser can be used to create an ultracompact infrared absorption spectroscopy spectrometer which can be carried by people. “By directing or the laser’s output onto the food under examination and analyzing the reflected light spectrum, we can rapidly decipher and reconstruct the chemical composition present in the food,” Dr. Guo says. “Also, compared to other chip-scale spectrometer techniques, our laser can generate very bright signal light, which increases the accuracy of the analysis.” This approach allows people to swiftly identify potential hazards, providing a valuable tool for ensuring food safety and protecting public health.
Traditionally, food safety inspections have been confined to laboratories, using sophisticated equipment inaccessible in people’s daily lives. Consequently, obtaining a clear understanding of food safety before eating is almost impossible. This new technology transforms this paradigm by miniaturizing the spectrometer to a size comparable to phone cameras. “Now, food safety inspections can be effortlessly conducted at home or in restaurants with a simple click on our phones,” Dr. Guo says. “This innovation significantly diminishes the risk of foodborne illnesses, making the [inspection] process more accessible and timely.”