Ghent University Researchers Develop An Ultrafast Component That Both Detects And Emits SWIR Light

From helping self-driving vehicles navigate through thick fog to identifying chemical compositions in food or biological samples: short-wave infrared (SWIR) technology enables applications that are not possible with ordinary visible light.

For example, SWIR light can see through dust and mist and allows certain materials and substances to be recognised by their unique ‘chemical fingerprint’.

At present, systems that use SWIR light are still relatively expensive. Quantum dots offer a promising solution: these are tiny crystals that can be incorporated into a liquid and applied or printed directly onto microchips.

“Quantum dots can make SWIR technology much more affordable,” says Dr Yu-Hao Deng, BOF postdoctoral researcher at Ghent University and lead author of the study. “But until now, separate components were still needed to emit and detect SWIR light. Bringing these different components together is technically complex and makes production more expensive.”

One component with two functions
Researchers at Ghent University have now succeeded in developing a single component capable of both detecting and emitting SWIR light. For a long time, this was difficult to achieve because the two functions place different demands on the material. Good light detection generally requires a thicker active layer, whilst fast operation and efficient light emission actually benefit from a very thin layer.

The research team managed to bridge this contradiction using an ultra-thin structure of high-quality quantum dots, combined with a so-called optical microcavity. This enhances the interaction between the material and the light. As a result, the same compact component can function both as a photodetector (which captures SWIR light) and as an LED (which emits SWIR light itself).

Lightning-fast response
The new component also operates exceptionally quickly, responding within 2 nanoseconds when detecting light and within 12 nanoseconds when emitting it. A nanosecond is one billionth of a second.

By combining both functions in a single component, the technology can be integrated into electronic systems more easily and cost-effectively. The Ghent University researchers therefore see potential applications in, amongst other things, optical chips, LiDAR systems, imaging and future smart communication devices.