AJ Fleisher (right) and Tobias Herman (left) with the experimental setup. A laser produces light that is manipulated on the table to create two optical frequency combs. The light from these combs is combined and fed into the fiber optic cable that contains the photonic sensor, which is located inside a well with a controlled temperature. Finally, the light signal is read by RF detectors.
Credit: Jennifer Lauren Lee/NIST
Photonic thermometers, which measure temperature using light, have the potential to revolutionize temperature measurement by being faster, smaller, and more robust than traditional thermometers. In essence, the sensors work by passing light into a structure that is sensitive to temperature. The light that comes out of the device gives scientists information about the temperature to which the sensor was exposed.
Someday, these tiny thermometers – and additional types of photonic sensors, which measure strain, humidity, acceleration, and other quantities – could be embedded into structures such as buildings or bridges as they are built. By measuring these properties as concrete or cement is setting, photonic sensors could give engineers valuable information about how the structure has formed, which can help them project how the structure will fare in the long term.
But one problem researchers haven’t yet solved is the best way to “interrogate” these photonic sensors – that is, to put light in and get light out. Traditional methods, which involve using lasers to create each frequency of light that enters the sensor, are difficult, slow, expensive, and bulky.
Red laser light (for demonstration purposes) in a fiber optic cable. ..
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