Harnessing the Dark Side: Optical Singularities Could Be Used for a Wide Range of Applications

Harnessing the Darkish Facet: Optical Singularities May Be Used for a Huge Vary of Purposes


Heart-Shaped Phase Singularity Sheet

Cross-section of the designed heart-shaped section singularity sheet. The prolonged darkish area within the heart picture is a cross-section of the singularity sheet. The section is undefined on the singularity sheet. Credit score: Daniel Lim/Harvard SEAS

Once we take into consideration singularities, we have a tendency to think about large black holes in faraway galaxies or a distant future with runaway AI, however singularities are throughout us. Singularities are merely a spot the place sure parameters are undefined. The North and South Pole, for instance, are what’s referred to as coordinate singularities as a result of they don’t have an outlined longitude.

Optical singularities usually happen when the section of sunshine with a particular wavelength, or shade, is undefined. These areas seem fully darkish. At the moment, some optical singularities, together with optical vortices, are being explored to be used in optical communications and particle manipulation however scientists are simply starting to grasp the potential of those methods. The query stays — can we harness darkness like we harnessed mild to construct highly effective, new applied sciences?

Now, researchers from the Harvard John A. Paulson Faculty of Engineering and Utilized Sciences (SEAS) have developed a brand new method to management and form optical singularities. The approach can be utilized to engineer singularities of many shapes, far past easy curved or straight strains. To display their approach, the researchers created a singularity sheet within the form of a coronary heart.

Polarization Properties

The singularity engineering process was additionally utilized to creating extra unique singularities, corresponding to a polarization singularity sheet. Right here, the polarization properties (e.g. polarization azimuth, ellipticity angle, and depth) of the experimental structured mild discipline is in comparison with the numerical predictions. Credit score: Daniel Lim/Harvard SEAS

“Typical holography strategies are good at shaping mild, however battle to form the darkness,” mentioned Federico Capasso, the Robert L. Wallace Professor of Utilized Physics and Vinton Hayes Senior Analysis Fellow in Electrical Engineering at SEAS and senior creator of the paper. “Now we have demonstrated on-demand singularity engineering, which opens up an enormous set of potentialities in wide-ranging fields, from super-resolution microscopy strategies to new atomic and particle traps.”

The analysis is revealed in Nature Communications

Capasso and his workforce used flat metasurfaces with precisely-shaped nanopillars to form the singularities. 

“The metasurface tilts the wavefront of sunshine in a really exact method over a floor in order that the interference sample of the transmitted mild produces prolonged areas of darkness,” mentioned Daniel Lim, a graduate pupil at SEAS and first creator of the paper. “This method permits us to exactly engineer darkish areas with remarkably excessive distinction.”

Metasurfaces Nanopillars Nanofins

Metasurfaces, that are nanostructured surfaces containing shapes like nanopillars (left) and nanofins (proper), had been employed to comprehend these singularity buildings experimentally. The above picture reveals scanning electron microscope photos of titanium dioxide nanostructures that had been used to exactly form the wavefront of sunshine in producing the singularity sheets. Credit score: Daniel Lim/Harvard SEAS

Engineered singularities might be used to lure atoms in darkish areas. These singularities might additionally enhance tremendous high-resolution imaging. Whereas mild can solely be targeted to areas about half a wavelength (the diffraction restrict) in dimension, darkness has no diffraction restrict, that means it may be localized to any dimension. This enables darkness to work together with particles over size scales a lot smaller than the wavelengths of sunshine. This might be used to offer info on not solely the dimensions and the form of the particles however their orientation as properly.

Engineered singularities might prolong past waves of sunshine to different forms of waves.

“You can even engineer lifeless zones in radio waves or silent zones in acoustic waves,” mentioned Lim. “This analysis factors to the potential for designing complicated topologies in wave physics past optics, from electron beams to acoustics.”

Reference: “Engineering section and polarization singularity sheets” by Quickly Wei Daniel Lim, Joon-Suh Park, Maryna L. Meretska, Ahmed H. Dorrah and Federico Capasso, 7 July 2021, Nature Communications.
DOI: 10.1038/s41467-021-24493-y

The Harvard Workplace of Know-how Growth has protected the mental property referring to this undertaking and is exploring commercialization alternatives.

The analysis was co-authored by Joon-Suh Park, Maryna L. Meretska, and Ahmed H. Dorrah. It was supported partially by the Air Pressure Workplace of Scientific Analysis underneath award quantity FA9550- 19-1-0135 and by the Workplace of Naval Analysis (ONR) underneath award quantity N00014-20-1-2450.

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