WiFi technology has become more and more popular, but more and more people complain that wireless signals are unstable, Internet access is slow, and WiFi hotspots are too few. Now, there is a new technology that may solve these problems. The light bulb has always been regarded as a symbol of the inspiration that inventors dream of. But for German physicist Herald Haas, the light bulb itself inspired him. Haas and his team at the University of Edinburgh invented a patented technology, which uses a flash to wirelessly transmit digital information. This kind of technology is often called visible light communication (VLC). Haas said: "My biggest idea is to turn light bulbs into broadband communication equipment. Such a light bulb can not only provide lighting, but also become a necessary tool. " Haas believes that by adding a microchip to an ordinary LED light bulb to make the light bulb flash at an extremely fast speed, data can be sent by using the light bulb. And the flashing frequency of light bulbs reaches millions of times per second. In this way, LED bulbs can transmit binary codes quickly. But for the naked eye, such flicker is invisible and can only be detected by a photosensitive receiver. Haas said: "This is similar to sending Morse code through a torch, but it is faster and uses an alphabet that computers can understand." This technology means that as long as you have a light bulb, you can get a wireless Internet connection. At present, there are about 14 billion light bulbs in the world. In fact, this also means that any street lamp can become an Internet access point. However, the visible optical communication technology nicknamed "Li-Fi" can not only improve the coverage of the Internet. As the most important technology of wireless data transmission, WiFi uses radio frequency signals. However, radio waves account for only a small part of the entire electromagnetic spectrum. With the increasing demand of users for wireless Internet, the available radio frequency spectrum is becoming less and less. For example, when surfing the Internet in a coffee shop, if there are more and more people surfing the Internet around you, you will find that the internet speed becomes very slow. The same is true for 3G mobile networks. At the same time, according to Cisco's data, the amount of information sent through mobile devices is doubling every year. Haas said that his technology will be an important part of the solution to the problem. He said: "The visible spectrum is 1, times wider than the radio frequency spectrum." This means that visible light communication can bring higher bandwidth. Haas said that "Li-Fi" technology can bring up to 1Gbps data transmission speed. Haas believes that his technology has an important advantage, that is, there is no need to build any new infrastructure. However, the transmission of traditional RF signals requires energy-intensive equipment. He said: "We use existing equipment. The visible spectrum is not utilized and not regulated, so we can conduct high-speed communication. " However, this technology has its own limitations. Thomas Kamalakis, a lecturer in informatics at Harokopio University in Athens, recommended Haas technology, but also said that the potential of this technology should not be overestimated. He said: "An obvious problem is that visible light cannot penetrate objects, so if the receiver is blocked, the signal will be cut off." Mark Leeson, an assistant professor at the School of Engineering, University of Warwick, UK, also holds the same view. He put forward: "The question is, how do our mobile phones use visible light to communicate?" Haas said that these are two real problems, but he also has a simple temporary solution. "If the optical signal is blocked and you need to use the device to send information, you can seamlessly switch to the RF signal." He believes that visible light communication is not a competitor of WiFi, but a complementary technology, which will help release spectrum space. He said: "We still need WiFi and a radio frequency communication system. You can't use light bulbs to send data to fast-moving objects or to objects behind trees, walls and obstacles. " In a short time, visible light communication can realize some small-scale applications. For example, this technology can be used in airplanes to help mobile phones and laptops surf the Internet, and it can also be used in places where radio waves cannot spread underwater. Haas pointed out that Li-Fi technology brings high security, because visible light can only travel in a straight line, so only people who are in the straight line of light transmission may intercept information.