Anti-atmospheric turbulence high-speed coherent laser communication device based on few-mode parallel mixing

The invention discloses an anti-atmospheric turbulence high-speed coherent laser communication device based on few-mode parallel mixing. The invention relates to the technical field of free laser communication. In order to solve the problems that an existing space laser transmission system is low in detection sensitivity, low in transmission rate and low in coupling efficiency, a few-mode opticalfiber is used for receiving signal light subjected to atmospheric turbulence, and the signal light amplified by a few-mode erbium-doped optical fiber amplifier and local oscillation light containing multiple modes are subjected to parallel frequency mixing in a space optical mixer; then hierarchical demultiplexing of multiple modes and multi-level coherent receiving of the modes are completed on the four paths of signals after frequency mixing through a photon lantern and a balance detector; and finally the signals are converted into digital signals through an analog-to-digital converter and then processed through a d