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First-in-world non-resonant laser technology using scattering cavity

Laser (Light Amplification by Stimulated Emission of Radiation) technology has had a significant impact on human life thus far. It has led to various new applications, in areas such as barcode scanners, printers, ultra high-speed optical communication, GPS, and even virtual/augmented reality, aerospace, and automobile industries. Laser technology uses optical resonators installed on the left and right sides of a material and another specific material (called the “Gain material”) to collect light with constant wavelengths and directions of travel and then amplify and emit them. The gain meterial, therefore, has an important role to play. Professor YongKeun Park and his research team have proposed a new approach of using a different gain medium. With its high efficiency and unidirectional properties, this new gain material for laser technology is expected to be used in various industries including military operations, bioscience, medical science, etc.

Higher light amplification achieved by making hole in proposed structure

The conventional laser technology used an encapsulating structure (laser resonator) to amplify light with a medium such as a mirror. Since the path of light entering the resonator must be kept constant, a special, transparent material such as crystal had to be used until now. However, Prof. Park and his team proposed a new non-resonant approach using an opaque substance and a hole in the structure. This is meaningful in that it brings a new option for gain medium materials. Now that various elements other than crystal can be used as gain medium, the wavelength of light can be further expanded,
thus enabling the use of high-powered lasers. The team made a hole in a fish-trap looking structure to collect light so that the light was continuously amplified inside, unable to escape from the cavity. This method made the path of escaping light unidirectional, as the structure was designed such that the light entering can only escape the cavity through the entryway. The results of the experiment showed that the trapped light inside continued to be amplified constantly by the surrounding gain medium.

This new structure with higher efficiency and unidirectional tendency can be used in various industries for high-powered laser technology

What Prof. Park and his team suggested was an entirely different approach with laser oscillation in this unique, spherical laser cavity with scattering surfaces, instead of the conventional laser oscillation using resonance phenomenon in a cavity. This technology has unchallenged potential as of now, since it is not subject to the influences of temperature or humidity.

“We had numerous meetings on physics and novel materials when we brainstormed at an early stage of the study, but after we decided to make a hole in the structure, the rest progressed smoothly,” commented Prof. Park on the process of the study.

This study was sponsored by the Ministry of Science and ICT (Leading researcher support project by National Research Foundation), as well as by the KAIST Advanced Institute for Science-X; it was published in Nature Communications on January 4th, 2021.

Prof. YongKeun Park
2020 KI Annual Report

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