Remote, Aerial, Trans-Layer, Linear and Non-Linear Downlink Underwater Acoustic Communication

摘要

Abstract-Both the linear mechanism for optical to acoustic energy conversion are explored for opto-acoustic communication from an in-air platform to a submerged vessel such as a submarine or unmanned undersea vehicle. This downlink communication can take the form of a bell ringer function for submerged platforms or for the transmission of text and/or data. The linear conversion mechanism, also known as the linear opto-acoustic regime where laser energy is converted to sound at the air-water interface, involves only the heating of the water medium. In this mode of operation, the acoustic pressure is also linearly proportional to the laser power. In contrast, the non-linear conversion mechanism, also known as the non-linear optoacoustic regime where focused laser energy is converted to sound at the air-water interface, involves a phase change of the water medium through evaporation and vaporization which leads to the production of a plasma. In this mode of operation, the acoustic pressure is non-linearly related to the laser power. The non-linear conversion mechanism provides a more efficient, i.e. higher source level, yet less controllable method for producing underwater acoustic signals as compared to the linear mechanism.