Local phase lock quadrature polarization free space coherent light communication device

Abstract

The invention relates to a local phase lock quadrature polarization free space coherent light communication device. The local phase lock quadrature polarization free space coherent light communication device comprises a single frequency single mode laser device, a fiber polarization beam splitter, a fiber stretcher, a first light phase modulator, a second light phase modulator, a data signal generator, a microwave amplifier, a first fiber collimator, a second fiber collimator, a first emission half-wave plate, a second emission half-wave plate, a first polarization beam splitting prism, a third emission half-wave plate, a second polarization beam splitting prism, a first rectangular prism, a first focusing lens, a second focusing lens, a first balance detector, a loop filter, a reception half-wave plate, a third polarization beam splitting prism, a second rectangular prism, a third focusing lens, a fourth focusing lens, a second balance detector and an A/D converter. The device emits coaxial quadrature polarization signal light, realizes self-interference reception at a reception end and can effectively overcome a phase error, a locking phase structure is arranged at an emission end, the structure of the reception end is simplified, and the system communication rate can be flexibly adjusted with no need for adjusting the light path.

Description

technical field [0001] The invention relates to free-space coherent optical communication, in particular to a local phase-locked orthogonal polarization free-space coherent optical communication device. Background technique [0002] In satellite-to-ground laser communication, a larger amount of data requires a higher communication rate. Compared with the optical communication method of direct detection by intensity modulation, the coherent optical communication mechanism is due to its higher theoretical limit sensitivity, higher spectral efficiency and better The characteristics of anti-background light noise interference have attracted extensive attention of researchers. Atmospheric interference, especially atmospheric turbulence, which causes the space-time random variation of atmospheric refractive index, is one of the main factors affecting satellite-ground coherent laser communication. Compared with the homodyne or heterodyne coherent detection method using the local o...

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Problems solved by technology

[0004] The invention provides a local phase-locked orthogonal polarization free-space coherent optical communication device, which can overcome the phase interference of atmospheric turbulence and does not require complex optical phase-locked loops or electric phase-locked loops in combination with self-differential interference reception in satellite-ground coherent laser communication Advantages, a local phase-locked orthogonal polarization is designed for the shortcomings of the DPSK receiving structure, which is not easy to adjust the communication rate and the pupil matching system must be introduced. The device introduces a local phase-locked system at the transmitter to compensate for the phase error between the transmitted orthogonal polarization optical paths , the emitted orthogonally polarized light is phase-modulated by the forward and reverse microwave data signals respectively and combined into a coaxial beam for emission. The signal light received at the receiving end is received by the polarization interference self-difference and detected by the balance detector, and finally recovered. transmitted data signal

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