The research work was published in the prestigious scientific journal Nature Photonics, which was led by a group of researchers from the Department of Applied Physics and the Center for Nanoscience and Nanotechnology at the Hebrew University. "A breakthrough, it's a dream!", the researchers excitedly announced following the findings
The nanoscience and nanotechnology revolution affects our daily lives in a variety of fields, starting with new materials for energy, through information processing and communication, precise instrumentation and ending in the fields of medicine. The miniaturization of devices and components to the dimensions of a few nanometers brings with it quantum phenomena that must be dealt with on the one hand, and on the other hand they can be utilized for the benefit of scientific and technological breakthroughs. In the laboratory of Prof. Uriel Levy from the Department of Applied Physics and the Center for Nanoscience and Nanotechnology at the Hebrew University, they have been developing nanophotonic chips for a variety of applications for several years. Recently, the laboratory succeeded in developing millimeter-sized chips, with nanometer shapes inside them - miniaturized optical structures made of silicon, together with miniaturized cells containing vapors of rubidium atoms. Although it sounds complex, these chips are our future, and they are already used by us today as the basis for advanced devices such as sealed watches, magnetic field sensors, frequency stabilization devices and more.
A major difficulty in realizing the technology and integrating it in a maximal way in everyday life lies in the fact that these are large and complicated devices, which are manufactured manually and at relatively high costs, consume quite a bit of power, occupy a significant volume, and it is difficult to integrate them with advanced electronic circuits on a chip. This is where the laboratory for nanophotonics at the Hebrew University came into action. "The laboratory achieved an unprecedented breakthrough with the help of the design and manufacture of a hybrid chip containing nanophoton circuits, which incorporate the same rubidium atoms within them," says Prof. Levy. "With the help of this breakthrough, the laboratory studied the physics of the chips and demonstrated their potential in a variety of applications."
But not everything was rosy. It turned out that miniaturization is indeed very important in order to reduce volumes and power consumption, and is of course critical for reducing costs and integration with electronics, but the very miniaturization damages the accuracy of the device. "The atoms move very quickly, pass quickly past the miniaturized light beam inside the optical chip, collide frequently with the cell walls and thus cause a deviation in the operating frequency, a deviation that significantly reduces the accuracy of the device", the researcher explained the scientific aspect of the damage. Another breakthrough was required, which did come.
The current breakthrough enables, on the one hand, maintaining the principles of miniaturization and on-chip integration, and on the other hand, obtaining maximum accuracy, approaching that obtained in larger cells. "The main innovation is based on the design and production of nanometer optical waveguides, which resemble thin wires with a thickness of several nanometers that are realized in the form of thin membranes, and look under the microscope like bridges suspended in the air. The size of these nanometer waveguides is much smaller than the wavelength and they are surrounded by rubidium atoms from all directions. These wires are actually disconnected from the substrate on which they sit, and they can be designed so that the dimensions of the light beam moving inside these wires allow the light to be absorbed by the atoms, while maintaining maximum accuracy and optimal performance," emphasizes the researcher.
This breakthrough also allowed the research group to obtain unique chips, with improved performance, as well as to demonstrate their importance in a variety of applications such as laser frequency stabilization at the highest level, and even uncomplicated processes that enable the conversion of information from one wavelength (color) to another wavelength, while maintaining on atomic precision. The entire research paper, describing all these achievements, has been published in the prestigious newspaper Nature photonics, in which he took a significant part Dr. Roi Zaktzar From the Department of Applied Physics and the Center for Nanoscience and Nanotechnology.
And what does the future hold? There are still many challenges. In the nanophotonics group, the chips continue to be developed and perfected, with the goal of continuing to miniaturize them, and integrate with other components in the circuit such as lasers and detectors. In this way, it will be possible to further reduce the production of the chips and make them even more attractive. In the future, we may see this technology penetrating our cell phones, and being used as a basic device in the components of the "Internet of Things" (the ability of our smartphone to control electrical appliances such as home lighting, washing machines, etc.), which require minimal power consumption and high precision. Also, in collaboration with a new research group in the department of applied physics led by Dr. Liron Stern, who was an important partner in the original development of the technology, the researchers believe that these chips will be able to be integrated into precise measurement and sensing systems, suitable for our mobile phones, based on the innovative technology of "frequency combs on a chip".
Furthermore, and perhaps more importantly, the researchers believe that after many years without a particularly significant and visible generational leap in mobile devices, the application of the technology they developed may lead to the long-awaited technological leap. "Our cell phone has many sensors. The very fact that our chips are smaller, cheaper and more miniaturized should allow their integration into devices such as the cell phone. These chips are able to be used as sensors of time, frequency, electric fields, magnetic fields, measurements and the like. Therefore, if we eventually put them in the phone, we will be able to realize navigation functions without the need for a relevant GPS in places without reception, create holograms of faces or of numbers and letters for typing like you see in futuristic movies, it will be possible to measure brain waves and the phone may also be able to read our thoughts (when we put the phone close to the head), we will probably be able to find lost metals behind walls - like car keys that everyone is looking for in the morning (the metals affect the electric and magnetic fields), and other creative things that we haven't thought of yet. Everything is of course at the level of speculation, unfortunately not yet something that is going to happen tomorrow morning."
In conclusion, Prof. Levy says that "the miniaturized hybrid chips will be the ultimate chips that can be mass-produced at low costs, light weight, integration, minimal power consumption and excellent accuracy over wide frequency ranges. The small dimensions, low power and low costs will make the technology in question something practical. This research is simply the fulfillment of my dream!" concludes Prof. Levy.
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