An international Yale-led research team has pursued a new approach to stabilizing high-power lasers by fighting chaos with chaos.
The demand for high-power lasers for applications such as material processing, large displays, laser surgery and LIDAR remote sensing systems (Light Detection and Ranging). A long-term challenge for high performance lasers is taming their irregular pulsations and chaotic fluctuations in emission power and beam profile. These problems hinder practical applications requiring stable, controllable laser light.
Previous strategies for reducing temporal fluctuations have involved decreasing the number of modes that the laser could use. As a result, none of the previous approaches are scalable to the performance levels required for an increasing number of applications.
"We present a radically different approach based on the new principle of combating laser chaos with wave-dynamic chaos," said Hui Cao, principal investigator of a study published on August 1
This video shows the numerically calculated field distribution within a D-shaped cavity measured emission from the even segment of the cavity boundary:
"We use wave chaotic or disordered cavities to destroy the formation of self-organized structures such as filaments that cause instabilities, "Cao said. "Laser instabilities are suppressed by a chaotic cavity geometry, which is compatible with high-performance operation because it allows many spatial modes to occur simultaneously."
Stefan Bittner, a Yale research assistant and first author of the study, said the simplicity and robustness The new system makes it widely applicable for other high power lasers, including fiber lasers and solid state lasers. This novel approach of suppressing instabilities and chaos with complex geometries can also be applied to many other unstable dynamic systems
This video shows a typical trajectory of an optical beam in a D -shaped cavity. The associated wave fronts produce a complex interference pattern in the cavity:
Other Yale authors are Hasan Yilmaz and Kyungduk Kim. The research was conducted in collaboration with the theoretical group of Ortwin Hess at Imperial College London and the Qi Jie Wang-led nanofabrication group at Nanyang Technological University in Singapore.
Yale's research was supported by the Office of Naval Research and the Air Force Office of Scientific Research
Publication: Stefan Bittner, et al., "Suppression of Spatiotemporal Laser Instabilities with Wave-Chaotic Microcavities," Science 16 Aug 2018: eaas9437 DOI : 10.1126 / science.aas9437