Photonic-Enabled Doppler Frequency Shift Measurement for Weak Echo Signals Based on Optical Single-Sideband Mixing Using a Fixed Low-Frequency Reference

• Published in: Journal of lightwave technology 2021-05, Vol.39 (10), p.3121-3129
• Main Authors: Chen, Yang, Zuo, Pengcheng, Shi, Taixia, Chen, Yu
• Format: Article
• Language: English
• Subjects: Binary phase shift keying; Doppler frequency shift measurement; Error analysis; Frequency analysis; Frequency measurement; Frequency shift; Low speed; Mach-Zehnder interferometers; microwave photonics; Nonlinear optics; Optical communication; Optical filters; Optical mixing; Optical modulation; Optical polarization; optical single-sideband mixing; Optical variables measurement; Photoelectric effect; Photoelectric emission; photonic signal processing; Photonics; reference signal; Single sideband transmission
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2021.3057429

A simplified photonic-enabled Doppler frequency shift (DFS) measurement approach is proposed based on a single dual-polarization binary phase-shift keying (DP-BPSK) modulator with the help of a fixed low-frequency reference. The low-frequency reference and the transmitted signal are combined and then single-sideband mixed in the upper dual-drive Mach-Zehnder modulator (DD-MZM) in the DP-BPSK modulator to generate an optical sideband of the transmitted signal and a mixed optical sideband of the two signals, which is combined with the optical sideband of the echo signal from the other DD-MZM. The combined optical signal is detected in a low-speed photodetector. Both the direction and the value of the DFS can be measured by analyzing the frequency of the generated photocurrent. An experiment is performed. DFS from -100 to 100 kHz is measured for microwave signals from 6.9 to 16.1 GHz with a measurement error of less than ±0.04 Hz. The stability of the system is also studied, and the change of the measurement error is less than ±0.04 Hz in 30 minutes.