Infinite polarization tracking system and method for light polarization state

Abstract

The invention belongs to the technical field of optical communication, and more particularly relates to an infinite polarization tracking system and method for a light polarization state, and the method comprises the following steps: a secondary phase modulator receives a beam of polarized light emitted by an optical transmitter, adjusts the polarization state of the polarized light and outputs signal light, and the signal light comprises first signal light and second signal light; the extraction module extracts the optical power of the signal light in the X and Y polarization directions and converts the optical power into an electric signal; the processing module receives the electric signal and processes the electric signal to obtain the optical power difference in the X and Y polarization directions; the processing module processes the electric signal through a dither algorithm to obtain a Stokes vector of the current signal light, and obtains a control voltage signal according to the Stokes vector; and the secondary phase modulator performs polarization state adjustment on the polarized light according to the control voltage signal, so that the output signal light tends to a circular ring of S1 = 0 on the Poincare sphere. According to the invention, the stability of the light polarization state can be realized through the two-stage phase modulation structure.

Description

technical field [0001] The invention belongs to the technical field of optical communication, and more specifically relates to an infinite polarization tracking system and method of optical polarization state. Background technique [0002] Coherent optical communication systems have the advantages of high sensitivity, long relay distance, large communication capacity, and multiple modulation modes, and have been widely used. Coherent optical communication mainly uses coherent modulation and heterodyne detection technology. Coherent modulation uses the transmitted signal to change the frequency, phase and amplitude of the optical carrier, so the optical signal needs to have a definite frequency and phase, while heterodyne detection is at the receiving end. A beam of local oscillator light and signal light are coherently coupled in an optical coupler to obtain a beat frequency signal whose frequency, phase and amplitude change according to the same law as the signal light. Co...

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Problems solved by technology

[0004] For this reason, Chinese patent CN112485930A discloses a control method and system for realizing polarization stabilization, which quickly adjusts the output light polarization state of any input light polarization state to any specified target on the Poincar sphere through a fast positioning algorithm Near the polarization state, the stochastic gradient descent algorithm is used to further stabilize the polarization state of the output light to the target polarization state, so as to achieve the stabilization of any polarization state to any set target polarization state; however, it needs to be adjusted by the five-level equivalent phase difference The polarization controller composed of fixed-angle wave plates is used for adjustment, and when the voltage applied to the current three-stage wave plate reaches the limit, it is necessary to roll back the voltage of the first three-stage wave plate to the middle voltage in order to continue to adjust the voltage. Such a scheme is too complicated and cannot To achieve infinite tracking of the polarization state of light, the adjustment control speed will inevitably be affected, and the control effect is not good

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