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A study led by electrical engineers from Duke University showed that changing the physical shape of a class of materials used in electronics as well as near- and mid-infrared photonics, called chalcogenide glasses, could extend their use in visible and ultraviolet wavelengths.

As Science Daily reported, that means they can be used in biological imaging, environmental monitoring, and underwater communications, aside from their commercial use as detectors, lenses, and optical fibers.

 Changing Physical Shape of Chalcogenide Glasses Could Unlock Visible, Ultraviolet Applications
(Photo : Wikimedia Commons)
Germanium selenium chalcogenide glass structure

What are Chalcogenide Glasses?

Chalcogenide glasses are a class of materials used in electronics and photonics. As its name suggests, it contains one or more chalcogen elements that include Arsenic, Sulfur, Selenium, Tellurium, Germanium, Antimony, and Phosphorus.

According to a book, titled "Infrared Fibers and Their Applications," some very stable and simple glasses could result from heating and mixing these elements in an oxygen-free environment. For instance, one of the oldest chalcogenide glasses ever made was that of an arsenic trisulfide (As2S3), which is dark red and is very stable.

Science Direct reported that chalcogenide glasses can be regarded as glassy semiconductors, and are suitable materials for solid membranes of solid-state chemical sensors, which can be turned into discrete sensors and low-selective sensor arrays.

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Breaking Limitations of Chalcogenide Metasurfaces

As mentioned in the report of Science Daily, chalcogenide glasses contain several chalcogens that make them a strong choice for advanced electronic applications, such as molecular fingerprinting, optical switching, and ultra-small direct laser writing. However, they have long been constrained to near- and mid-infrared photonics because they strongly absorb wavelengths of visible and ultraviolet wavelengths.

Electrical and computer engineering Professor Natalia Litchinitser from Duke University said that chalcogenide glasses have always had this fundamental limitation. Recent research about nanostructures that affect how chalcogenide glasses respond to light demonstrated a way to break these barriers.

But this has only been used in infrared parts of the electromagnetic spectrum, which means that it is still not suitable for applications in visible and ultraviolet wavelengths.

In the study, titled "Near-Infrared to Ultra-violet Frequency Conversion in Chalcogenide Metasurfaces" published in Nature Communications, researchers showed in their experiments a near-infrared to ultraviolet frequency conversion in As2S3-based metasurface. This was possible because of a phase locking mechanism between the pump and the third harmonic signal's inhomogeneous component.

According to the study, the phase locking enabled the inhomogeneous component to propagate along with the pump pulse and encountered similar effective dispersion as the infrared pump. Therefore, little to no light was absorbed that led to the opening of previously unused spectral range for chalcogenide glasses, and novel applications.

The researchers said that they are working on a new study to find out if it is possible to engineer different shapes of chalcogenides that can carry harmonic signals better than nanostrips. For example, they are looking at making Lego-like blocks that are spaced apart at specific distances to develop a more stable signal. More so, they predict that stacking metasurfaces would enhance the effect.

This approach could unlock visible and ultraviolet applications for electronics and photonics that were previously impossible.

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