▎ 摘　　要

NOVELTY - The system has a sound which will cause the vibration of a photo-generating device (6) when sound is generated at the receiving end, and generate an echo signal with a Doppler frequency. A photo-detector (7) is provided to collect the mixed light composed of the intrinsic light emitted by a listening laser (4) and the echo signal emitted by the photo-generating device, convert the Doppler frequency shift information in the mixed light into a corresponding photocurrent signal and transmit it to a decoder (8). The decoder is provided for analyzing the Doppler frequency shift carried in the photocurrent signal, so as to obtain the vibration spectrum and amplitude of the photo-generating device, so as to restore the sound information of the receiving end. The photoacoustic characteristic material on the photo-generating device is a graphene material. USE - Bidirectional photoacoustic communication system for use in active receiving device. ADVANTAGE - The system is easy to realize long-distance directional transmission of sound information due to the small emission angle of the laser and its strong directivity, and the receiving end directly hears the sound without an active receiving device. The system realize bidirectional communication of far distance point-to-point by converting the light energy into sound energy, and has strong confidentiality and strong anti-electromagnetic interference ability. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a communication method using the bidirectional photoacoustic communication system. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the bidirectional photoacoustic communication system. (Drawing includes non-English language text) Microphone (1) Encoder (2) First coding laser (3) Listening laser (4) Photo-generating device (6) Photo-detector (7) Decoder (8) Second coding laser (9)