TU-TESL

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According to foreign media reports, researchers from the National Institute of standards and Technology (NIST) and colleagues have developed an optical switch that can transfer light from one computer chip to another at a speed of 2 billion one second, faster than any other similar device. The compact switch is the first optical switch capable of operating at a sufficiently low voltage, so it can be integrated into a low-cost silicon chip and can change the direction of light with a very low signal loss. The switch has record performance and is an important step in building a computer that processes information using light rather than electricity. Relying on light particles - photons have several advantages in transmitting data in a computer. First of all, photons are faster than electrons and do not waste energy because they need to heat computer components. Managing waste heat is a big obstacle to improving computer performance. For decades, optical fiber has been using optical signals to transmit information over long distances. However, optical fiber will occupy too much space, so it can not be used to transmit data on computer chips. The new switch combines nanometer sized gold and silicon optical elements, electronic elements and mechanical elements, all of which are tightly packed together, and can import and export light from a micro channel, change the speed of light and change the direction of travel. One nanometer is one billionth of a meter, about one 100000 times the width of human hair. Christian Haffner of NIST, the Federal Institute of technology in Zurich and the University of Maryland, who co authored the study, said the device had numerous applications. In cars, the switch can quickly change the direction of a beam of light, so that the beam must continue to scan all parts of the road at the same time, helping the driverless car to measure its distance from other cars and pedestrians. The device can also replace power circuits with more powerful optical circuits in neural networks. These are all artificial intelligence systems, which can simulate the way that neurons in human brain make decisions in complex tasks such as pattern recognition and risk management. The new technology hardly uses energy to change the direction of light signals, which can help to realize quantum computing. Quantum computer can deal with the data stored in the subtle relationship between the specially prepared subatomic particle pairs, which is extremely fragile. It requires the computer to work at ultra-low temperature and low power consumption, and the less interference the particle has, the better. Because the new type of optical switch is different from the previous one, it needs little energy, so it can become a part of quantum computer. Haffner and NIST's Vladimir aksyuk and Henri lezec say their findings will surprise many in the scientific community because they do not conform to the theory that has long been believed. Some researchers think that the photoelectric mechanical switch is not practical because of its large volume, slow running speed and high voltage requirements for computer chip components, which is hard to bear. The switch makes use of the fluctuation of light. When two identical light waves meet, they can be superposed, so that the peaks of one light wave align or strengthen the peaks of the other light wave, thus creating a bright mode called constructive interference. If two light waves are not fully synchronized, the trough of one light wave will cancel the peak of the other light wave, resulting in a dark mode called destructive interference. The team designed a beam of light to be confined to a tiny highway, a tubular channel called a waveguide. The linear freeway is designed with an off ramp (ramp) to allow some light to enter the raceway like cavity, which is only a few nanometers away from the ramp and etched on a silicon disk. If the wavelength of light is appropriate, it can rotate around the runway several times before leaving the silicon cavity. The switch also has an important component: a gold film is suspended at tens of nanometers above the silicon disk. Some of the light propagating on the silicon runway will leak out and hit the film, leading to the oscillation of the electron group on the surface of the film. Such oscillations, known as plasmons, are a mixture of light and electron waves: the oscillating electrons are similar to the incident light waves because they vibrate at the same frequency, but their wavelengths are much shorter. Shorter wavelengths allow researchers to manipulate isoions over distances of several nanometers, which are much shorter than the length of the original light wave, and then convert the oscillations into light, which in turn makes the light switch very compact. By changing the gap width of only a few nanometers between the silicon disk and the gold film, researchers can delay or advance the phase of the mixed light wave (that is, the time point when the wave reaches the peak or valley). The researchers used static electricity to bend the gold film, and even if the gap width changed only slightly, the phase would change greatly. When two beams of light recombine on the highway, depending on whether the researchers delay or advance the phase of the light wave, the two beams will either interfere with each other for a long time or cancel the interference. If the beams match, resulting in interference with each other, the light will continue along the original direction, all the way along the pipeline. If the beams cancel and interfere, the channel will be blocked. Instead, the light must move in other directions, which are determined by other waveguides or paths placed near the blocked channel. In this way, light can be transferred to any computer chip at will. Scientists once thought that the isosomatic ion system would greatly weaken the light signal, because photons would penetrate the inner part of the gold film, causing electrons to absorb most of the light energy. However, researchers have proved that the hypothesis is wrong, the device is very compact, and its design ensures that almost no photons will penetrate the film, and the loss of optical signal is only 2.5%, compared with the loss of the previous switch of 60%, which makes the switch still in the prototype stage, but it can still be applied in the commercial field. Now, the team is trying to shorten the distance between the silicon disk and the gold film, make the equipment smaller, further reduce the signal loss, and make the industry more interested in the technology.