All That Matters

Credit: Yushin Kim, Korea Advanced Institute of Science and Technology

How does a lens work? Well, as the light arrives at the lens it gets bent towards the focal point of the lens. The denser the lens material is in comparison to the surrounding air, the more it is deflected. The materials property that quantifies this effect is the refractive index.

For lenses, the general rule is that a larger refractive index is better. That’s because the maximum resolution of a lens gets better as the refractive index increases. This is of crucial importance for applications where resolution matters, for example in the fabrication of semiconductor transistors, says Xiang Zhang, a physicist from the University of California in Berkeley. “A large index is very useful for high-resolution imaging and lithography. That’s what the billion dollar semiconductor industry critically needs and have investigated in heavily.”Typically, the refractive index varies anywhere between 1 (air) and 3. That of window glass is about 1.5.

Bumki Min from the Korea Advanced Institute of Science and Technology (KAIST) along with colleagues from other institutions now have demonstrated an artificial material whose refractive index is a staggering 38.6. Their paper is published in this week’s issue of Nature.

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