Frequency shift elimination method based on multi-wavelength relevant optical communication system

Abstract

The invention discloses a frequency shift elimination method based on a multi-wavelength relevant optical communication system and relates to the field of an optical communication system. Reference light which is not modulated at a receiving end enters the local oscillation input end of a 90-degree mixer; local oscillation light with a wavelength corresponding to the reference light enters the signal input end of the 90-degree mixer; after photoelectric conversion, an electrical signal with frequency shift opposite to that of electrical signals with other wavelengths subjected to photoelectric conversion is obtained; and in an electric field, the electrical signal is respectively multiplied by electrical signals with other wavelengths subjected to photoelectric conversion to effectively eliminate the frequency shift of a modulated light carrier and the corresponding local oscillation light. The method can be used for correcting and eliminating large-scale frequency shift, the tolerance degree of the system to the frequency shift can be improved. In addition, the system has low requirements on the amount of lasers; a corresponding wavelength division multiplexing structure has relatively simple structure; an optical terminal of a coherent receiving end does not need feedback devices, such as phaselocked loops, automatic frequency control devices and the like; the structure of the multi-wavelength relevant optical communication system is simplified; and system cost is saved.

Description

technical field [0001] The invention relates to the field of optical communication systems, in particular to a frequency offset elimination method based on a multi-wavelength related optical communication system. Background technique [0002] With the explosive growth of information generated by the application of communication technologies such as video conferencing and the popularization of the Internet, higher transmission performance requirements are put forward for the physical layer that is the basis of the entire communication system. But for non-coherent detection, the potential for future improvements is limited by the sensitivity of the receiver, especially when multi-level modulation is used. On the other hand, coherent detection has the recognized advantages of high sensitivity and can realize all-optical amplitude modulation, multi-channel polarization technology and fiber loss compensation technology. The huge advantages of coherent detection and the developme...

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Problems solved by technology

[0004] However, conventional methods such as phase-locked loops and automatic frequency control units use feedback to control frequency offsets through hardware. To eliminate the impact of frequency deviation on system performance, and increase the complexity of digital processing operations, and the range of frequency deviation that can be compensated is limited, which limits the practicability of coherent reception under existing conditions

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