New approach to localizing light beyond diffraction limit could revolutionize quantum technology

Imagine a groundbreaking achievement in light science and technology that has long been a dream: shrinking light to the size of a tiny water molecule, unlocking a world of quantum possibilities. Recent advancements by researchers from Zhejiang University have brought us closer to this incredible feat, as they made significant progress in confining light to subnanometer scales.

Traditionally, localizing light beyond its typical diffraction limit faced challenges in precision fabrication and optical loss. But now, a new waveguiding scheme reported in Advanced Photonics holds the promise of unlocking the potential of subnanometer optical fields.

Here’s how it works: Light starts its journey in a regular optical fiber, passes through a fiber taper, and arrives at a coupled-nanowire-pair (CNP). Inside the CNP, the light transforms into a remarkable nano-slit mode, generating an incredibly confined optical field, possibly as tiny as just 0.3 nm. This novel approach boasts an impressive efficiency of up to 95% and a high peak-to-background ratio, offering a plethora of new possibilities.

But the excitement doesn’t stop there. The new waveguiding scheme also extends its reach into the mid-infrared spectral range, pushing the boundaries of the nano-universe even further. Now, optical confinement can reach an astonishing scale of approximately 0.2 nm (λ/20000), opening up even more avenues for exploration and discovery. The potential applications of this technology are simply mind-boggling.

Waveguiding scheme to generate a sub-nm-confined optical field in a nano-slit mode. (a) Schematic illustration of the CNP waveguiding scheme. (b) 3-D plot of the cross-sectional field intensity distribution of the nano-slit mode. Credit: Advanced Photonics (2023). DOI: 10.1117/1.AP.5.4.046003

Professor Limin Tong, leading the Zhejiang University Nanophotonics Group, emphasizes the unique advantages of the new waveguiding scheme, setting it apart from previous methods. Unlike its predecessors, this scheme operates as a linear optical system, offering a plethora of benefits. It enables broadband and ultrafast pulsed operations, making it versatile and powerful. Additionally, the combination of multiple sub-nanometer optical fields becomes possible, leading to exciting opportunities for engineering spatial, spectral, and temporal sequences within a single output.

The animated demonstration provided by the authors in the video summary brings this groundbreaking concept to life. It showcases the immense potential of such advancements, leaving us in awe of the possibilities that lie ahead.

The implications of this breakthrough are staggering. The localization of the optical field to such an extent that it can interact with individual molecules or atoms opens up new frontiers in light-matter interactions, super-resolution nanoscopy, atom/molecule manipulation, and ultrasensitive detection. It is as if we are on the verge of unlocking the secrets of the tiniest realms of existence, embarking on a journey of discovery like never before. The future is filled with promise, and we are poised to explore and shape the nano-universe in ways we never imagined possible.

Source: SPIE

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