The future of LED optical communications is expected to be more rapid in the face book laboratory published in the concept of light sensors

Today's high-speed cable networks use lasers to transmit information to the optical fiber, but wireless networks currently use radio or microwave communications.

Modern science and technology may realize the wireless communication through the light, for example, there is an example of the use of LED lights for network information transmission. Facebook Connectivity Lab researchers demonstrated conceptual results to detect atmospheric optical communication signals.

Facebook team in the field of Optica, an important international journal of optoelectronics, describes the new technology can lay the foundation for the future of fast optical communication network, transmission network services to remote areas.

The science and technology development of Facebook's lab aims to provide affordable Internet services to about 4 billion people worldwide. The research team host Tobias Tiecke said: "there is a high proportion of the population is still unable to enjoy the convenience of network, mainly because the infrastructure of wireless communication can not reach these areas are mostly in remote areas around the world. "The communication technology we are developing is used to mean the residents who are isolated from these homes.

Optical communication is also called free space optical communication (free-space optical communications), with different fiber and network technology to provide mobile communications base stations to reach the area, is a kind of economic method is more affordable. The laser light delivery information into space may provide very large bandwidth and information transmission capacity, but there is a major challenge, that is exactly how the transmission of a very small with laser light to a distant, very tiny light sensors.

In the new study, face book researchers have proposed a solution, they do not use the traditional optical fiber, but the use of fluorescent materials to focus and gather light in a small sensor. The use of this area of 126 cm2 surface of the collector, collecting light from all directions, while the use of existing telecommunications technology to achieve the amount of information transmission 2Gbps.

Tiecke said: "we use fluorescent fiber to absorb a color of light and emit another color. The light absorbed by the optical fiber comes from all directions, the light emitted by the optical fiber, the light is collected into very small units and quickly through the sensor. "

The demand of high speed communication for high speed sensor

High speed free space optical communication networks need high-speed optical sensors to receive laser light to transmit messages. But the transmission speed must be balanced with larger size; while the receiver is the subject of visible light for receiving light or laser, but the larger volume of detection speed is slow.

To track the position of the sensor can use a series of Optics and mechanisms, and issued a directive to allow the light sensor to target laser light, but these methods make the whole process is somewhat complicated. The new sensor uses a plastic optical fiber containing an organic dye to absorb blue light and emit green light. This setting successfully replaced the past for guiding the light to collect the traditional optical and action platform Tiecke said: "it can emit fluorescence fiber absorption characteristics of different colors also have wider brightness into the advantages of the system. This method has been used in solar collectors, but the speed of the solar collector light transmission is not the focus. We find that the same concept can also be applied to communications, addressing the difficulties of guiding and tracking light, while maintaining the advantages of high-speed transmission. "

In optical communications applications, the time required to convert from blue light to green light is less than 2 nanoseconds (about 2/1000000000 seconds), so the speed meets the demand. In addition, the use of orthogonal frequency division multiplexing (orthogonal frequency division, referred to as OFDM), although the bandwidth is only 100MHz, researchers can transmit more than 2Gbps of the amount of information transmission multiplexing. Orthogonal frequency division multiplexing (OFDM) is a kind of digital modulation technology. Although commonly used in wired, wireless communications, but rarely used for laser communications.

"We can use materials that are not used for information transmission, but also to achieve such a large amount of information transmission. The team hopes to be able to attract more people to develop these valuable materials of interest, suitable for communication tailored materials. "

If the material is developed to the infrared wavelength, the human eye can not see the light, but the infrared speed can be faster than blue, green. The new approach theoretically allows free space optical communications to rise to more than 10Gbps.

Gather light from all directions

In the internationally renowned Journal Optica, the researchers demonstrated the shape of the light bulb sensor. The optical sensor is made up of a series of fluorescent optical fibers. Although it can also be made into other shapes, the shape of the bulb can provide very large bandwidth and full range of sense, which means that mobile devices can be moved around to detect the message.

The researchers also showed that the geometry can collect up to 126 square centimeters of light, so that it is less sensitive to alignment. Our sensors collect the same energy, but also send the same energy independent signal. The research team is also planning to make the technology into an early round, can be measured. Tiecke said: "we are studying the possibility of commercial products, which is a very new system, and there is much room for development in the future. "

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