World's Thinnest Lens Developed by International Research Collaboration


International Research Team Develops World's Thinnest Lens

Researchers from the Institute of Physics (IOP) at the University of Amsterdam and their colleagues at Stanford University have joined forces to create a remarkable breakthrough in lens technology. Their collaboration has resulted in the development of the world's thinnest lens, an astonishing feat of engineering that measures just three atoms in thickness. This innovative lens, unlike its traditional counterparts, does not rely on curvature to bend light. Instead, it employs quantum effects to achieve its extraordinary capabilities.

The research team crafted this flat lens using a unique material known as tungsten disulfide (WS2). Despite its diminutive size, measuring half a millimeter in width and an incredible 0.6 nanometers (nm) in thickness, this lens packs a powerful punch. To put this into perspective, a human hair is typically between 80,000 and 100,000 nm thick, making this lens a true marvel of miniaturization.

While conventional lenses, which have been in use for over two thousand years, rely on refraction to bend light as it enters and exits the curved glass, the researchers took a radically different approach. Their ultra-thin lens features concentric rings of WS2 and works on the principle of diffraction, a design known as a Fresnel or zone plate lens. The focal length of the lens is determined by the size and spacing of these rings, rather than the lens's thickness.

The lens's remarkable properties arise from quantum effects within the WS2 molecules. When light strikes the lens, electrons in the material absorb the light and jump to higher energy levels. Due to the lens's ultra-thin nature, the electron and the positively charged hole it leaves behind remain bound together through electrostatic attraction, forming what is known as an exciton. These excitons quickly recombine, causing the lens to emit light at specific wavelengths, making it highly efficient for certain applications.

During their experiments, the researchers observed a clear peak in lens efficiency at specific wavelengths at room temperature, with even higher efficiency achieved when the lens was cooled down. While the lens only directs a portion of the incident light to its focal point, allowing the rest to pass through unaffected, the team sees this as an advantage for applications where light transmission should remain undisturbed while still allowing for information collection from a small portion of the light.

Jorik van de Groep, an assistant professor at IOP who contributed to the research, envisions potential applications for this lens in wearable devices, such as augmented reality glasses. "The lens can be used in situations where the view through the lens should not be disturbed, but a small part of the light can be tapped to collect information. This makes it perfect for wearable glasses, especially for augmented reality applications," he explained.

The research team is now focusing on refining the coatings on these lenses to enable electrical adjustments. Van de Groep noted, "Excitons are very sensitive to the charge density in the material, and therefore we can change the refractive index of the material by applying a voltage."

This groundbreaking development in lens technology, born from the collaborative efforts of researchers at the IOP at the University of Amsterdam and Stanford University, has the potential to revolutionize the field of optics and imaging. As the team continues to refine and enhance their ultra-thin lens, it is clear that their work will have far-reaching implications for a wide range of applications, from wearable devices to augmented reality and beyond.