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Optical Tweezers Can Now Manipulate Matter on a Nanoscale

Plasmonics helps optical tweezers trap matter on the scale of tens of nanometers

2 min read
Optical Tweezers Can Now Manipulate Matter on a Nanoscale
The image on the left is an electron beam microscopy image of the extremity of the plasmon nano-tweezers. The image on the right is a sketch illustrating the trapping of a nanoparticle in the bowtie aperture.
Institute of Photonic Sciences

Optical tweezers—more formally known as “single-beam gradient force traps"—have been a key instrument in manipulating matter in biology and quantum optic applications since Bell Labs described an instrument in 1986. The problem for the tool’s use in nanoscale applications is that it couldn’t really manipulate particles smaller than a few hundred nanometers.

Now researchers at the ICFO-The Institute of Photonic Sciences near Barcelona, Spain have taken optical tweezers to a new level by employing plasmonics to make it possible for the instrument to manipulate objects in three dimensions .

Plasmonics takes advantage of the surface plasmons that are generated when photons hit a metal structure. The surface plasmons are essentially oscillations in the density of electron fields. Plasmonics has a number of applications ranging from the transmitting of data on computer chips to producing high-resolution lithography.

In this application, the plasmonics confine light to a very small dimension that accentuate the capabilities of nano tweezers, which involves focusing a laser light into a small spot. This focused laser light serves as an attractive force to small particles that become “trapped” in the beam of light. The plasmonic structure further confines the light from the laser.

In the IFCO work, which was published in the journal Nature Nanotechnology (“Three-dimensional manipulation with scanning near-field optical nanotweezers“), the researchers were able to attach a plasmonic device that took the shape of bowtie aperture to the extremity of an optical fiber.

The result of this addition has allowed the researchers to manipulate particles in three dimensions as small as a few tens of nanometers using a low, non-invasive laser intensity. The researchers were able to move a nanoparticle over tens of micrometres over a period of several minutes.

While this new tool will no doubt excite the imagination of molecular manufacturing adherents, who are looking to build macroscale products from nanoscale objects piece by piece, its initial applications are more likely to be in medical research to better understand the biological mechanisms that lead to disease.

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3 Ways 3D Chip Tech Is Upending Computing

AMD, Graphcore, and Intel show why the industry’s leading edge is going vertical

8 min read
Vertical
A stack of 3 images.  One of a chip, another is a group of chips and a single grey chip.
Intel; Graphcore; AMD
DarkBlue1

A crop of high-performance processors is showing that the new direction for continuing Moore’s Law is all about up. Each generation of processor needs to perform better than the last, and, at its most basic, that means integrating more logic onto the silicon. But there are two problems: One is that our ability to shrink transistors and the logic and memory blocks they make up is slowing down. The other is that chips have reached their size limits. Photolithography tools can pattern only an area of about 850 square millimeters, which is about the size of a top-of-the-line Nvidia GPU.

For a few years now, developers of systems-on-chips have begun to break up their ever-larger designs into smaller chiplets and link them together inside the same package to effectively increase the silicon area, among other advantages. In CPUs, these links have mostly been so-called 2.5D, where the chiplets are set beside each other and connected using short, dense interconnects. Momentum for this type of integration will likely only grow now that most of the major manufacturers have agreed on a 2.5D chiplet-to-chiplet communications standard.

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