Optical heterodyne detection

Coherent Systems

Published in Jerry D. Gibson, The Communications Handbook, 2018

where wIF = coS - cLO, (IF = (s - (LO and K is a constant. The third term in Eq. (53.3) is a beat component between the signal and the LO light. It is found to be a down-converted signal from the optical carrier frequency into the microwave beat frequency. This beat frequency is called an intermediate frequency (IF), and this process is called optical heterodyne detection. The obtained IF signal is fed into a heterodyne demodulator, which is basically identical to that used in radio communications, and then the baseband signal is regenerated.

Research and Experiment on Quench Detection Technology of HTS Current Leads Based on Distributed Optical Fibers

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Journal Information

Published in Fusion Science and Technology, 2020

Bin Chen, Jiangang Li, Yanlan Hu, Teng Wang, Chao Zhou

All information of amplitude and phase-modulated light waves can be extracted through modulation after satisfying the coherent condition. The photodetector converts the mixed signal generated when the signal light and the reference light are mixed into an electric signal, and after filtering and amplifying the signal, the difference in frequency signal between the signal light and the reference light can be obtained. Therefore, coherent detection is also called optical heterodyne detection.7

Optical heterodyne detection

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Coherent Systems

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