Deciphering the Enigmas of Light – Novel Technique for Steering Light’s Erratic Behavior Developed by Scientists

A team of researchers has mastered the manipulation of light’s varying frequencies by employing a custom-built cavity, potentially advancing the capabilities of fiber optics, which could enhance the management of energy, computation, and signal transmission. This achievement is acknowledged by Xuefeng Jiang.

The study of how light interacts within an oval-like setting has offered scientists key insights into its intricate dynamics.

The ability to manage light is crucial for progress in several technological fields, including energy collection, computational processes, telecommunications, and medical diagnostics. However, light’s complex nature often makes it challenging to regulate effectively.

Physicist Andrea Alù likens the unpredictability of light in disordered systems to a billiard game, where even minor changes in the strike of the cue ball can significantly alter the direction and interactions of the balls on the table.

“In the game of billiards, small discrepancies in how you hit the initial ball can create a wide variety of movement patterns of the balls on the table,” Alù, a noted Physics professor at the CUNY Graduate Center, explained. “Similarly, light within a chaotic cavity is hard to predict – conducting the same experiment repeatedly with almost identical conditions can yield varying outcomes.”

In a recent article featured in Nature Physics, Alù’s team at the CUNY Graduate Center introduced a pioneering method to modulate light’s erratic behavior by customizing its diffusion patterns through light itself. The initiative was spearheaded by Xuefeng Jiang, formerly a postdoctoral scholar in Alù’s group and now an assistant professor at Seton Hall University, and Shixiong Yin, a doctoral candidate under Alù.

Traditional Systems vs. Chaotic Cavities

Typical methods for analyzing light involve uniform-shaped resonators where light predictably echoes and spreads, forming distinct frequencies and spatial patterns. In standard resonators like a circular cavity, specific frequencies correlate with certain modes, simplifying the physics involved. However, this simplicity does not reveal the complexities of light seen in more intricate systems, according to Jiang.

“A cavity accommodating chaotic light patterns can generate thousands of light configurations from a single frequency, which was initially thought to make control of the optical response impractical,” Jiang stated. “Yet, we have shown that managing this chaos is indeed possible.”

The Groundbreaking Stadium-Shaped Cavity

To overcome these challenges, the researchers engineered an expansive, stadium-shaped cavity with an exposed top and dual passages at opposite ends for channeling light into the structure. A camera mounted overhead captures the patterns and intensity of light as it escapes, scattering within the cavity.

The device is equipped with adjustable elements to fine-tune the intensity and timing of the light entering through these paths. By manipulating the interplay of light within the cavity, the team was able to orchestrate one light beam’s pattern through the interaction with another, a strategy referred to by Alù as coherent control, which essentially means using light to regulate light. Altering the incoming light beams’ relative strengths and timing, the researchers could consistently transform the pattern of light emitted from the cavity.

Refining Control with Non-Reflective Scattering Modes (RSMs)

Achieving control was made possible by utilizing a special light behavior in resonant cavities known as “non-reflective scattering modes” (RSMs), a phenomenon predicted in theory but until now, not demonstrated in optical cavities. Yin highlighted that their ability to modulate RSMs signifies a stride in stimulating and directing complicated optical systems, relevant for energy storage, computing, and communication processes.

“We identified certain frequencies at which our system supports two distinct, intersecting RSMs that allow all the light to be drawn into the stadium cavity without reflecting back to the channels, facilitating its management,” Yin described. “Given that our system deals with optical signals within the operational range of everyday optical fibers, this discovery opens the door to improved methods of storing, directing, and controlling light in sophisticated optical systems.”

Looking forward, the researchers plan to integrate more adjustable elements into their studies to explore the intricate behaviors of light even further.

Citation: “Coherent control of chaotic optical microcavity with reflectionless scattering modes” by Xuefeng Jiang, Shixiong Yin, Huanan Li, Jiamin Quan, Heedong Goh, Michele Cotrufo, Julius Kullig, Jan Wiersig and Andrea Alù, 2 November 2023, Nature Physics.
DOI: 10.1038/s41567-023-02242-w

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