Today's high-speed cable to optical fiber communication network using laser transmitting information, but the wireless network USES radio and microwave communications at present.
Modern technology may realize through the light for wireless communications, for example there are using visible light leds for instance of the network information transmission. Facebook Connectivity Lab researchers shows the conceptual, detection in atmospheric optical communication signals.
Facebook team contributes in the photoelectric field international journals Optica, describe this new technology can quickly for the future optical communication network foundation, transmission network services to remote areas.
Facebook's technology aimed at the current of the development of the laboratory cannot obtain network of about 4 billion people worldwide with affordable web services. Host team Tobias Tiecke said: "there are a high percentage of the population is still unable to enjoy the convenience of the network can't touch, mainly because of the wireless infrastructure most of these areas for the remote areas of the world." Our purpose is the development of communication technology is in isolated residents hit the home.
Optical communication is also called free space optical communication (free space optical communications), with different technologies offer optical fiber network and mobile communication base hard-to-reach areas, is a kind of more economic benefits. Use laser light transmission may provide information to the space is very large amount of bandwidth as well as the information transmission, but there is a major challenge, that is exactly how to transmit a very small with laser light pointing to a distant, also very tiny light sensor.
In the new study, researchers face book puts forward a solution, but they don't use the traditional optical fiber using the fluorescent material to condenser as well as the light scatters in small light sensor. Collocation USES this covers an area of 126 square centimeters of the surface of the collector, collecting light, from all directions at the same time use the existing telecommunications technology to achieve 2 GBPS of information transmission.
Tiecke said: "we use the fluorescence optical fiber absorb one color of light and emits a light color. Light absorbed by the fiber by from all directions, the light emitted by optical fiber, the light scatters into very small units and quickly through light sensors."
High-speed communications demand for high speed sensor
High speed of free space optical communication network need to use high speed sensor to receive the laser light in conveying information. But the transmission speed must be balanced and comply with the size; Although larger receiver for receiving the light or laser light is a visible mark, but the greater the volume detection speed will be slow.
To track the location of the light sensors can use a series of optical and mechanism, and issue instructions to let light sensor aimed at laser light, but these methods make the whole process a bit complicated. New light sensor with organic dye examples of plastic optical fiber absorb blue and green. Such set successfully replaced the past used to direct light to the collection area of the traditional optical and motion platform Tiecke said: "the fluorescence optical fiber can launch its absorption characteristics of the different color also have the advantage of greater brightness into the system. This method has been used for solar energy collector, but solar light color of the light transmission speed is not the point. We found that the same concepts can also be applied in communication, solve the guidance and the difficulty of track light, while maintaining the advantages of high-speed transmission."
In terms of optical communication applications, from the blue light is absorbed to convert the time needed for the green light is less than 2 nanoseconds (two over one billion of a second), therefore conforms to the requirements on speed. In addition, the use of OFDM (orthogonal frequency division multiplexing, OFDM), although only 100 MHz bandwidth, the researchers were able to the amount of information transmission is greater than 2 GBPS throughput. Orthogonal frequency division multiplexing is a kind of digital modulation technology, let the multicarrier transmission of information can be transmitted at the same time. Although widely used in cable, wireless communication, but rarely used in laser communications.
"The material we can use was not used in information transmission, also reached such a large number of information transmission. The team hopes to attract more people's interest in developing these materials the author, tailor the suitable materials for communication."
If the material is corresponding to the infrared wavelengths that developed the human eye can't see the light, but infrared speed can more quickly than blue, green. A new method that will allow for the ascent of the free space optical communication to more than 10 GBPS.
Collect the light from all directions
In the international famous journals Optica, researchers showed light bulb in the shape of a light sensor. The light sensor is made up by a series of fluorescence optical fiber. Although also can make other shape, but the light bulb shape can provide very large frequency width and omnidirectional sensor, also will be able to move around on behalf of the mobile device can also detect messages.
Researchers also shows the geometry to the collected light of up to 126 square centimeter, let its low sensitivity to the arrangement. Our sensors to collect the same energy, at the same time also send signals of the same energy independent. Team are planning technology to make into a round, the early can be measured. Tiecke said: "we are studying the possibility of a commercial product, this is a very new system, and there is still much room for growth."
