How does laser seize the opportunity in communication field?

How does laser seize the opportunity in communication field? As a new light source, laser has the characteristics of high brightness, strong directivity, good monochromaticity and strong coherence. Laser communication uses laser as the carrier of information. Compared with traditional radio communication, satellite laser communication has many unique characteristics.

First of all, the carrier frequency of laser is in the order of hundreds of THz, which is 3~5 orders of magnitude higher than that of traditional radio communication with carrier frequency ranging from several GHz to several tens of GHz. It can carry more information and the communication rate is higher. Secondly, the laser divergence angle is small, the beam width is extremely narrow, the directivity is good, and it is not easy to be captured in space.

In laser communication, the equipment must be located in a narrow beam to receive a clear signal. Therefore, laser can be used for highly secure communication between two points, and multi-point secure communication can establish an anti-interception laser communication network, which is not easy to be interfered by the outside world and has better security and reliability.

At the same time, the wavelength of laser is 3~5 orders of magnitude smaller than that of radio. Compared with the devices needed for radio, the optical antenna, transmitting and receiving components and other devices needed for laser communication system are smaller in size and lighter in weight, which can meet the requirements of miniaturization, light weight and low power consumption. Although laser communication also has some limitations.

For example, the cost of laser communication is higher than that of microwave communication; In the process of laser transmission in the atmosphere, it will be greatly attenuated by snow, fog and rain, which will affect the communication quality; Moreover, the extremely high directivity of the laser beam also leads to high requirements for the stability and accuracy of the equipment.

But generally speaking, laser communication will be widely used in military field and high-speed data transmission in the future, which has become an international knowledge and trend.

Earlier, Derek Tournier, the administrator of NASA, said that laser communication can bring "a communication network with high bandwidth, low delay and low probability of signal interference, which is suitable for any platform, whether on water, ship or in the air".

In fact, the United States and other countries have taken the lead in the research of satellite laser communication technology a long time ago. For example, in 1968, researchers from Goddard Space Center of the National Aeronautics and Space Administration of the United States launched a laser beam from the ground station to GEOS-I II, a satellite in low earth orbit, and conducted laser transmission experiments to analyze the influence of atmospheric turbulence on laser signal transmission.

1985, the United States established a stable laser communication link by using high-precision tracking and aiming technology. In 20 13, the demonstration and verification project of American lunar laser communication was successfully implemented, which laid a deep technical foundation for the development of its satellite laser communication.