Underwater optical communication system and method based on single photon detection and circular polarization modulation

Abstract

An underwater optical communication system and method based on single photon detection and circular polarization modulation are provided, the system comprises a computer, a transceiver circuit, a self-stabilizing holder and an optical antenna, comprises a polarization demodulation optical path and a polarization modulation optical path. Beacon light is emitted from one end, received by a telescopeat the other end and recorded to form an imaging light spot position, and fine tracking is carried out accordingly; during communication, the combined light at one end is changed into circularly polarized light and then emitted to the telescope at the other end through the telescope; the signal light is converted into horizontally polarized light or vertically polarized light after being received, and enters the detector I or the detector II. Left-handed and right-handed polarization modulation is adopted. The system is composed of two same devices. The device can be used for water surface and underwater communication or underwater and underwater communication. Based on the single-photon detection technology, the detection precision of optical signals can be improved to the single-photonmagnitude, the underwater optical communication distance is effectively prolonged on the premise that the pulse intensity of emitted light is kept unchanged, and effective transmission of informationis guaranteed by adopting a circular polarization modulation method and a corresponding error correction scheme.

Description

technical field [0001] The invention relates to an underwater optical communication system, in particular to an underwater optical communication system and method based on single-photon detection and circular polarization modulation, and belongs to the technical field of single-photon detection, photon left-handed and right-handed polarization modulation. Background technique [0002] Conventional underwater wireless communication methods such as underwater acoustic communication, electromagnetic communication, etc. have a slow rate and low security, while blue-green light in the visible light band has a small attenuation coefficient in water, so blue-green lasers can be used to achieve high-speed underwater communication system. [0003] Single-photon detection technology has developed along with quantum information. Because the detection sensitivity can reach the level of a single photon, it can further increase the optical communication distance while keeping the power of...

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Problems solved by technology

[0004] If the underwater optical communication adopts the conventional intensity modulation method, because the optical pulse arriving at the single-photon level is due to factors such as water body channel absorption, detection efficiency, and photon number distribution in the pulse, many pulses will be lost during detection, and the It brings a large bit error rate to these communications, and it is difficult to attenuate the optical pulse to the single-photon energy level for normal communication

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