Trapping Light with Metamaterials

An anisotropic metamaterial waveguide cladding keeps light travel on track throughout a computer chip, preventing leaked and jumbled bits of information. (Source: Purdue Univ., S. Jahani)

Because processing infor­mation with light can be more efficient than with electrons used in current devices, there is good reason to confine light onto a chip. But light and the bits of information it carries tend to leak and scatter out of the tiny compo­nents that must fit on a chip. A Purdue Univer­sity-led effort has built a novel cladding along waveguides to prevent infor­mation leaks – particularly around sharp bends where light bounces off track and scatters. Information then gets lost or jumbled rather than communi­cated throughout a device. Preventing this could faci­litate the integration of photonic with electric cir­cuitry, increasing communi­cation speed and reducing power consumption.

“We want the bits of infor­mation that we are sending in the waveguide to travel along tight bends and simul­taneously not be lost as heat. This is a challenge,” said Zubin Jacob, Purdue assistant professor of electrical and computer engi­neering. What makes the waveguide cladding so unique is aniso­tropy, meaning that the cladding design enables light to travel at different velocities in different direc­tions. By controlling the aniso­tropy of the cladding, the researchers prevented light from leaking off track into other wave­guides where crosstalk of infor­mation would occur. Instead, bits of information carried by light bounce off by total internal reflec­tion and stay strongly confined within a waveguide.

“The waveguide we made is an extreme skin-depth structure, which means that any leakage that does happen will be really small,” said Saman Jahani, Purdue graduate research assistant in elec­trical and computer engi­neering. “This approach can pave the way for dense photonic inte­gration on a computer chip without worrying about light leakage.” (Source: Purdue U.)

Reference: S. Jahani et al.: Controlling evanescent waves using silicon photonic all-dielectric metamaterials for dense integration, Nat. Commun. 9, 1893 (2018); DOI: 10.1038/s41467-018-04276-8

Link: Birck Nanotechnology Center, Purdue University, West Lafayette, USA


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