The laser communication industry is developing rapidly and is about to enter a golden period of development

Laser communication is a kind of communication mode using laser to transmit information. Laser is a new type of light source, which has the characteristics of high brightness, strong directivity, good monochromism and strong coherence. According to the different transmission medium, it can be divided into atmospheric laser communication and optical fiber communication. Atmospheric laser communication is a laser communication using atmosphere as a transmission medium. Optical fiber communication is a communication mode using optical fiber to transmit optical signals.

The laser communication system consists of two parts: sending and receiving. The transmitting part mainly consists of laser, Optical modulator and optical transmitting antenna. The receiving part mainly includes optical receiving antenna, optical filter and Photodetector. The information to be transmitted is sent to a Optical modulator connected to the laser, which modulates the information on the laser and sends it out through an optical transmitting antenna. At the receiving end, the optical receiving antenna receives the laser signal and sends it to the optical detector, which turns the laser signal into an electrical signal and turns it into the original information after amplification and demodulation.

Each satellite in the Pentagon's planned mesh communications satellite network could have up to four laser links so they can communicate with other satellites, aircraft, ships and ground stations. Optical links between satellites are crucial to the success of the U.S. military's low-Earth orbit constellation, which will be used for data communications between multiple planets. Lasers can provide higher transmission data rates than traditional RF communications, but are also much more expensive.

The U.S. military recently awarded nearly $1.8 billion in contracts for the 126 Constellation program to be built separately by U.S. companies that have developed a one-to-many optical communication technology for point-to-multipoint transmission that could help reduce the cost of building the constellation by drastically reducing the need for terminals. A one-to-many connection is achieved by a device called a managed optical communication array (MOCA for short), which is unique in that it is very modular, and the MOCA managed optical communication array enables optical inter-satellite links to communicate with multiple other satellites. In traditional laser communication, everything is point-to-point, a one-to-one relationship. With MOCA, an inter-satellite optical link can talk to 40 different satellites. This technology is not only a benefit of reducing the cost of building satellite constellations, if the cost of nodes is reduced, there is an opportunity to implement different network architectures and thus different service levels.

Some time ago, China's Beidou satellite carried out a laser communication experiment, successfully transmitted the signal in the form of laser to the ground receiving station, which is of extraordinary significance for high-speed communication between satellite networks in the future, the use of laser communication can allow the satellite to transmit thousands of megabits of data per second, our daily life download speed is a few megabits to ten megabits per second, and once laser communication is realized, Download speeds can reach several gigabytes a second, and in the future can even be developed into terabytes.

At present, China's Beidou navigation system has signed cooperation agreements with 137 countries around the world, has a certain influence in the world, and will continue to expand in the future, although China's Beidou navigation system is the third set of mature satellite navigation system, but has the largest number of satellites, even more than the number of satellites of the GPS system. At present, the Beidou navigation system plays an important role in both the military field and the civilian field. If laser communication can be realized, it will bring good news to the world.