For a long time, an important reason restricting submarines to become the protagonists of naval warfare is that they cannot rely on electromagnetic waves to communicate effectively underwater. In the future, with the development of underwater communication technology represented by blue-green laser pointer communication, the era of “diving the sea” may be approaching.
In fact, in addition to submarine communications, blue-green lasers are also promising in naval equipment applications. The world’s military powers have successively invested a lot of manpower and material resources in the experimental research of blue-green laser detection, sounding, underwater sensing, and sea-based light control weapons, and have made a large number of technological breakthroughs. In 1967, the United States completed the world’s first blue-green laser sounding device. This type of underwater detection device can be used to detect and search the sunken shipwreck, survey and chart charts.
The US Navy used the blue-green laser system as the first development project for the development of mine detection equipment. During the Gulf War, the US military used laser mine detectors to find mines, which were dozens of times more efficient than sonar. In addition, underwater sensors are the “eyes and ears” of submarines and underwater robots, which play an important role in the timely detection and identification of underwater threat targets. The blue-green laser underwater sensing device can obtain higher recognition accuracy and positioning ability than other underwater sensors, and can even realize the tracking and direct attack of underwater targets by submarines.
Although blue-green laser communication has many advantages, there are many technical bottlenecks in specific applications. The laser beam is narrow, and the general transmission path is a straight line. When fighting in an area farther from the land, the submarine must rely on large aircraft and satellite platforms to emit communication lasers to specific waters. Once these platforms are destroyed, the submarine will likely become “blind” again. Therefore, the current technical means for submarine communication is still to use a long-wave radio station to roughly locate the submarine first, and then use laser communication to accurately communicate, but it will be severely limited by the communication quality and positioning accuracy of low-frequency communication.
At the same time, although the attenuation of the green laser pointer in water is small, the light wave passes through multiple interferences of carbon dioxide, water vapor, suspended particles, ozone molecules, and cloud and atmospheric turbulence along the way. Therefore, the laser emission device needs to adjust the emission angle in real time according to the external environment. Characteristic information such as intensity and frequency place high requirements on the adaptive optical system at the laser emitting end. These are all technical problems that need to be optimized and improved in blue-green laser communication.