American Chinese scientists gain major technological breakthroughs in the invention of graphene optical modems

According to a report by the Canadian Chinese Network on May 24, a team of Chinese professor Zhang Xiang, assistant professor Wang Feng and postdoctoral researcher Liu Ming of the University of California, Berkeley, developed the world's smallest graphene. Optical modem" (modem commonly known as "cat"). It is 400 times thinner than the hair, can transmit signals at high speed, and is expected to increase the speed by 10,000 times. It is just around the corner to download a high-definition movie in 1 second.

Graphene "electric shock" turned into "light switch"
In 2004, Hem and Novoselov, professors of physics at the University of Manchester, England, successfully separated graphene, the world's thinnest but hardest nanomaterial. Liu Ming and others took the opportunity to start researching optical modems made of graphene. They found that the energy of the electrons in the graphene (Fermi level) changes with different voltages applied, and whether the graphene absorbs light also determines its Fermi level. When a sufficient negative voltage is applied, the electrons are drawn out of the graphene and no longer absorb the photons, so when the photons pass through the graphene, the graphene is completely transparent and can "turn on" the light. When a positive voltage is applied, the electrons are tightly wrapped together and the photons cannot be absorbed. However, the researchers found that when the voltage is at a certain critical point, electrons can block the passage of photons, thereby "closing" the light. Thus, graphene has the ability to turn light on or off and can act as a modem.

In an instant postdocgoral Berkeley Liu HD movies very high speed network transmission, he said modem for modulating light switch, the electronic signal into an optical signal, transmit the digital information. The existing network transmission is mainly copper wire, which has reached the bottleneck stage. Scientists are studying the use of light to transmit information, but existing optical modems are either too costly or too bulky and too sensitive to temperature. The team's graphene modulators have transmission speeds of up to 1 GHz and theoretically reach 500 GHz. When the Internet reaches such a high speed, it is faster to share video information, and it takes only one second to download a high-definition movie to the mobile phone.

Embedding an optical modem into the CPU of a graphene modem has two major advantages, one is cheap and the second is small. At present, the optical modem on the market is $5,250, which is about RMB 34,000, while the graphene modem is only a few dollars. It's 400 times thinner than the hair, and can be combined with any device in the computer, and can eventually be integrated into a central processing unit (CPU).

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