Light routing by nanoscale nonlinear interferometry with attosecond control - Nature Nanotechnology

Light routing by nanoscale nonlinear interferometry with attosecond control – Nature Nanotechnology

Time Stamp: December 20, 2023 5:00 AM
Source Node: 3030866

Conventional electronics has its speed limit in the range of a few GHz and carries high losses due to thermal heating. Photonic technologies, which use photons instead of electrons, could potentially overcome these barriers, as processing rates can reach and surpass the THz range at lower losses. However, realizing compact photonic integrated circuits that can compete with modern microchips poses the challenge of operating at the nanometre scale, that is, at sub-wavelength volumes for optical and telecommunication frequencies. Resembling the transistor in electronics, all-optical modulators are at the heart of any information processing photonic device. Such nanoscale building blocks require ultrafast light-by-light control, which can be achieved through nonlinear optical effects. Writing in Nature Nanotechnology, Di Francescantonio et al.1 now report a dielectric metasurface — an ultrathin two-dimensional array of dielectric nanostructures — capable of mixing two pulsed pump beams to nonlinearly upconvert near-infrared light into visible light. They show controllable switching of the direction of emission between different diffraction orders of the metasurface, which acts as a sort of reconfigurable nonlinear diffraction grating. The routing tuning knobs are the light polarization states and the relative time delay of the excitation pulses, which the researchers adjust with 150 as precision. Strikingly, changing the relative arrival time of the beams at the metasurface by just 1 fs can shift the emission from one diffraction order to another with a modulation efficiency of up to 90%.

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