New technologies can help you figure out what’s wrong

Some people do things so clever and difficult that it’s hard to see what they have to do with you and me, so we ignore them. But this is often the wrong answer.

What if you had a simple device at home that could tell you why you feel so bad?

But what if this gadget could quickly check if you have COVID or the flu, or even detect that you have diabetes without knowing it? The device can understand everything without going to the doctor or the laboratory.

Holds light better

This technology could become a reality within a few years, and electrical engineers are among the people who make it possible to create such gadgets, which contain a key component called a whispering gallery-mode microresonator.

The new technology provides better optical sensors, essential for electronics, including devices that analyze chemicals using light.

We set up the microresonator in low-loss whispering gallery mode for the long-wave infrared spectrum. Since the long-wave infrared spectrum provides definitive information about chemicals, it opens up new possibilities for sensing applications. »

Dingding Ren, Researcher, Department of Electronic Systems, Norwegian University of Science and Technology (NTNU).

We will talk about what a microresonator is later in the article. But first, back to Ren. He and his colleagues have developed a new whispering gallery-mode microresonator that can hold light longer for certain wavelengths in resonance.

“Our microresonator is about 100 times better than what previously existed for the long-wave infrared spectrum,” Ren said.

“It can hold 100 times more light than previous versions, which enhances the optical field indoors and greatly facilitates non-linear processes such as creating frequency combs,” he said.

It opens up great opportunities

Keeping light waves more efficient in the infrared part of the light spectrum is good news for several types of new technologies, especially particle detection and spectroscopic chemical identification, which scan a gas/liquid sample for viruses, bacteria, and other harmful agents you might have. .

The new microresonator means that scientists can use these devices to develop broadband frequency combs in the long-wave infrared spectrum. And what could it be?

Frequency combs are laser lights whose spectrum consists of a series of discrete, evenly spaced frequency lines. These can be found in a variety of places, such as in GPS, atomic clocks, and the fiber optic equipment used in telephones and computers. If the broadband comb is available in the long-wave infrared spectrum, the technology also opens the door to the simultaneous analysis of multiple chemicals.

“The technology is still in its infancy when it comes to measurements in this spectrum of long-wave infrared light. But our improvement allows us to identify several different chemicals in real time in the near future,” says Ren.

This type of spectroscopic machine, called a Fourier Transform Infrared Interferometer, already exists, but they are so large and expensive that only hospitals and institutions with large budgets can afford them. Other, slightly simpler machines can analyze several chemicals, but not as many at once as new technology may make possible.

Ren worked closely with Professor David Burghoff and his colleagues at the University of Notre Dame, USA.

“Competition in this field is fierce,” says Ren.

The new microresonator is made of germanium element. The material may sound exotic, but it was used in the world’s first transistor as far back as 1947, before silicon took over the market.

Today, germanium is often used in optical lenses for infrared sensors and cameras, and is therefore neither rare nor expensive. These are also advantages when the theory is marketed.

What are microresonators?

Microresonators, a type of optical cavity, can store a high optical field in a very small volume. They can develop into a track or disk geometry, but they are usually microscopic in size, about the thickness of a hair. Inside the microresonator, light propagates in the form of circles, so the optical field is amplified.

“We can compare the microresonator to what happens with sound in the Whispering Gallery of St. Paul’s Cathedral in London,” says Ren.

This elliptical gallery created a famous phenomenon. You can whisper at one end and people on the other side of the room can hear you, even though they usually won’t be able to hear you at that distance. Sound waves are amplified by the shape of the room and walls, which is how light waves behave in a microresonator. If you want to try to understand this phenomenon better, you can read the research article. The link is below the article.

Funded by Fripro money

Ren is funding the research through a three-year Fripro project grant from the Research Council of Norway. Fripro’s money is dedicated to basic research.

“We promised to develop a better microresonator, and we achieved it,” said Ren. The research team followed through on its promise.

Great work

Professors Bjørn-Ove Fimland and Astrid Aksnes from NTNU’s Department of Electronic Systems provided guidance along the way.

“Ren has done an excellent job and this is confirmed by the publication of his article Nature Connection“, says Aksnes.

The fact that we can now measure the light spectrum in the long-wavelength IR range (8-14 µm or micrometers) opens up many possibilities for use in imaging and sensing, environmental monitoring and biomedical applications, Aksnes explains.

“Many molecules have fundamental vibrational bands in the mid-wave IR range (2-20 µm) called the ‘molecular fingerprint region’. By measuring in this waveband, we get higher sensitivity,” he says.

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