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The photonic radar

The research group of Prof. Erez Hasman from the Technion has developed a technology for compressing dozens of lenses on a nanometer surface. The research published in the journal Science paves the way for the creation of a completely new type of optical components with potential applications in medicine, food, communication and other fields

Schematic demonstration of different light beams, with angular momentum, emanating from nanoantenna arrays.
Schematic demonstration of different light beams, with angular momentum, emanating from nanoantenna arrays.

The journal Science reports on a new technology developed by the research group of Prof. Erez Hasman from the Faculty of Mechanical Engineering and the Russell Berry Institute for Nanotechnology at the Technion. This technology enables the compression of tens of lenses on a nanometer surface. Possible applications: development and testing of food and drug components, communication connections and communication signals, sending light beams to the required places, splitting the light at the end of an optical fiber, connecting several light beams, multifocal eye glasses with an unprecedented level of precision, and devices for quantum computing.
"Our source of inspiration," explains Prof. Hasman, "is the normal radar, based on the layout of antennas that transmit and receive different wavefronts. The challenge in moving from a radio wave radar to an optical radar is related to the fact that here we are dealing with much shorter wavelengths - in the 0.5 micron region - and the length of the antenna must be smaller than the wavelength."

The research was carried out by the research group for nano-optics led by Prof. Hasman, in which the research students Elhanan Magid, Igor Yulevich, Dekal Wechsler and the researcher Dr. Vladimir Kleiner participate, in collaboration with Prof. Mark Brungersma from Stanford University. The group showed that by spatially mixing different antennas it is possible to produce many wavefronts from a common optical key. "The approach we developed is expected to revolutionize functionality in optics," explains Prof. Hasman, "and it is based on a combination of the common key concept and meta-surfaces - a field I developed back in 2001." This combination paves the way for the application of multifunctional components, i.e. components capable of performing several operations at the same time, and in fact for new types of optical components."

Metasurfaces are thin optical elements, about the thickness of a hair, on which tiny antennas (nanoantennas) are spread. The position and orientation of the antennas determines the properties of the tiny optical components, therefore the precise control of the antenna layout is essential for the performance of the device. The group applied techniques to create nanoantenna arrays in order to obtain multiple special wavefronts, such as light beams with angular momentum. This achievement was used for the simultaneous measurement of the spectrum and polarization of the light, enabling integrated spectro-polarimetric analysis on the chip.
In an article in Science, selected for early publication by the editors, various methods for the implementation of multi-functionality in metasurfaces are presented. The unique arrangement of the nanoantennas allows researchers to focus light rays and divert them in the desired directions while controlling the degree of spin of the photon. The spin, i.e. the internal angular momentum, is a property of the light particle that describes the direction of the photon's spin.

The researchers took advantage of these features and developed a component that is able to measure the wavelength and polarization of light simultaneously, in one measurement. It is actually a spectro-polarimeter with a size of about 50 microns, which allows its integration in small and advanced diagnostic systems in medicine and other fields. In the article they presented a characterization and a distinction between two types of glucose - left (L) and right (D). Morphologically, the two types of glucose are enantiomers, meaning an exact mirror image of each other - like a pair of hands. This property is called chirality. Since glucose changes the polarization of light, the researchers measured the properties of light scattered from the glucose solution using the metasurfaces they developed and were thus able to differentiate between the two types of glucose.
This distinction between the two types of glucose is important since mammals have enzymes that know how to break down glucose D but not glucose L, therefore only enantiomer D is biologically active. Furthermore, since most biological molecules are chiral, distinguishing between the enantiomers has wide implications in the pharmaceutical and food industries. Thalidomide, for example - the same anti-nausea drug that caused thousands of cases of birth defects in the XNUMXs - was based on a chiral molecule, one enantiomer of which does relieve morning sickness in pregnant women but the other harms the development of the fetus.

Prof. Hasman heads the laboratory for micro- and nano-optics in the Faculty of Mechanical Engineering and in the RBNI (Russell Berry Institute for Research in Nanotechnology) at the Technion. According to him, "besides the knowledge we have accumulated here through many years of work, the Technion has a very advanced infrastructure at a world level, which allows us to develop and produce very pioneering nanotechnology." He proudly notes Israel's place on the world optical map. "Israel, and not just the Technion, is definitely an empire in optics. There are world-leading research groups here as well as a very impressive industry."

Prof. Hasman completed his doctorate at the Weizmann Institute and then worked and led development for a decade in the civil industry

and the security In 1998, in view of the shortage of optical engineers, he was offered to establish an optical engineering track at the Technion in the Faculty of Mechanical Engineering - and he accepted the offer. According to him, "Today, it is clear that an engineering background, however extensive, is incomplete without an in-depth scientific background, and this is the gap we are filling here: training engineers with a deep understanding of optical sciences. Today, this track provides the industry with many graduates with in-depth knowledge of optics, trains many doctoral students, and there are even professors in the academy who grew up here in the optical engineering track."

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