Harnessing and controlling light is crucial for advancements in various fields, from energy harvesting to communication. However, the complex behavior of light presents challenges when it comes to effective control. Physicist Andrea Alù compares the behavior of light in chaotic systems to a game of billiards. Just as tiny variations in the break shot can lead to different patterns of bouncing balls, light rays also exhibit chaotic behavior in certain environments. In a recent study published in Nature Physics, a team of researchers at the CUNY Graduate Center introduced a new platform for controlling light’s chaotic behavior by manipulating its scattering patterns using light itself.
Traditional methods for studying light’s behavior often involve circular or regularly shaped resonant cavities, where light bounces and scatters in predictable patterns. In such systems, only specific frequencies of light survive, each associated with a specific spatial pattern or mode. While this approach is sufficient for understanding the physics in circular cavities, it fails to capture the full complexity of light behavior seen in more intricate platforms. Consequently, controlling the optical response in chaotic systems has been deemed challenging.
To address this challenge, the team of researchers designed a stadium-shaped cavity with an open top and two channels on opposing sides, allowing light to enter. As incoming light scatters off the cavity walls, a camera captures the amount of light escaping the stadium and the resulting spatial patterns. The cavity features knobs to control the intensity of light and the delay between the two input beams. By causing the beams to interfere with each other through the opposing channels, the researchers successfully employed coherent control – using light to control light.
The manipulation of light’s behavior in the cavity was made possible by a rare phenomenon called “reflectionless scattering modes” (RSMs). While RSMs had been theoretically predicted, this study was the first to observe them in optical cavity systems. By adjusting the relative intensity and delay of the light beams entering the channels, the researchers consistently altered the light’s radiation pattern outside the cavity. This discovery holds immense significance for energy storage, computing, and signal processing, as it enables efficient excitation and control of complex optical systems.
The ability to manipulate RSMs opens doors for better storage, routing, and control of light signals in complex optical platforms. The findings of this study specifically address optical signals within the bandwidth of fiber optics, which are extensively used in our daily lives. However, the researchers intend to expand their studies by incorporating additional knobs to gain further control over the behavior of light. By introducing more degrees of freedom, they hope to unravel even greater complexities in the manipulation and control of light.
The study conducted by the team of researchers at the CUNY Graduate Center has paved the way for a new era of controlling light’s chaotic behavior. By designing a stadium-shaped cavity and utilizing coherent control, they successfully managed to manipulate the scattering patterns of light and observe reflectionless scattering modes. This breakthrough has significant implications for a wide range of applications, including energy storage, signal processing, and computing. As further research continues, the team plans to explore additional avenues for controlling and harnessing the full complexity of light’s behavior.