Method and system for transmitting and receiving by orthogonally dual-polarized differential quaternary phase shift keying

Abstract

The invention relates to a method and a system for transmitting and receiving by orthogonally dual-polarized differential quaternary phase shift keying. The system comprises a transmitting device and a receiving device, wherein the transmitting device comprises a continuous laser; the continuous laser is connected with a polarization beam splitter which is connected with a DQPSK modulator; the DQPSK modulator is connected with a precoder of which the output end is connected with a tunable optical attenuator or a polarization controller; and the polarization controller is connected with a polarization beam combiner; and the receiving device comprises a DQPSK demodulator, and the DQPSK demodulator is connected with a balanced detector which is connected with a decision circuit. In the method, four paths of electrical signals can be multiplexed, and only one demodulator and two balanced detectors are used at a receiving end to demodulate two orthogonally polarized DQPSK signals at the same time; therefore, compared with D8PSK and x-QAM systems, the system has the advantages of greatly reducing the complexity and remarkably enhancing the stability of components.

Description

technical field [0001] The invention relates to the field of digital communication, in particular to a method for transmitting and receiving by orthogonal dual polarization differential quadrature phase shift keying and a system thereof. Background technique [0002] A variety of modulation methods are used in digital communication systems. Among them, polyphase key shift modulation is valued for its good spectrum utilization and bit error rate performance. Polyphase key shift is a modulation format that stores information in the phase of the transmitted signal. With the rapidly growing demand for large-capacity communication in the information society, operators in the optical fiber communication industry are currently upgrading single-channel 10Gbit / s systems to 40Gbit / s systems, and are also accumulating technologies for upgrading to 100Gbit / s or even 160Gbit / s systems . [0003] At present, the methods to achieve 100Gbit / s optical transmission system mainly include wave...

AI Technical Summary

Problems solved by technology

The prior art has the following disadvantages: although differential 8-phase phase-shift keying (D8PSK) and multi-level quadrature amplitude modulation (x-QAM) code patterns can multiplex more than 3 electrical signals, the structures of the transmitting and receiving parts are both Super complex, and some special components are not very stable, such as the π / 8 phase shifter used in the D8PSK demodulator is difficult to achieve accurate stability; several Mach-Zehnder used in the multiplexer The modulator (MZM) is also difficult to achieve complete symmetry; moreover, the D8PSK demodulation system uses 4 Mach-Zehnder interferometer optical paths, 4 balanced detectors, and an XOR gate circuit, which is very complicated

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