A team of international scientists out of Germany, Italy, and Australia have published a paper in the journal nature communications that describes their recent breakthrough in lightwave manipulation. The authors have managed to shape the lightwaves so quickly the changes are being measured using femtoseconds (quadrillionths of a second)
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Before modern materials, light manipulation was performed using conventional optical components such as lenses, mirrors, and prisms. These components allowed for controlling of light, but their response times were limited by factors such as mechanical movement and the speed of electronic signals in control systems. As a result, the manipulation of light in previous technologies generally occurred on slower timescales, typically on the order of microseconds (millionths of a second) to milliseconds (thousandths of a second).
In recent years, the use of nonlinear optical materials, plasmonic structures, and metasurfaces has enabled more rapid control over light waves. The researchers utilized polarization-sensitive wavefront-shaping metasurfaces in combination with monolayer Transition Metal Dichalcogenides (TMDs) to control the light in their experiments.
The polarization-sensitive metasurfaces are designed to manipulate the wavefronts of light waves. This means they can control the phase, amplitude, and polarization of the light passing through them. The researchers integrated monolayer TMDs, such as tungsten diselenide (WSe2), into their experimental setup. When illuminated with light, these TMDs can generate second-harmonic signals that are sensitive to the polarization of the incident light.
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By combining the polarization-sensitive metasurfaces with the monolayer TMDs, the researchers were able to exploit the second-harmonic generation properties of the TMDs to control the behavior of light passing through the metasurfaces. The manipulation of the light waves occurs through all-optical means, meaning that the control is achieved using only light itself, without the need for external electrical or mechanical stimuli.
Overall, by combining polarization-sensitive metasurfaces with monolayer TMDs, the researchers were able to achieve precise and ultrafast control over the wavefronts of light, enabling novel applications in areas such as high-speed communications and ultrafast optics.
Sinelnik, A., Lam, S.H., Coviello, F. et al. Ultrafast all-optical second harmonic wavefront shaping. Nat Commun 15, 2507 (2024). https://doi.org/10.1038/s41467-024-46642-9
Image Credit: Sinelnik, A., Lam, S.H., Coviello, F. et al.
You can read the full paper here.