Carrier Leakage Analysis and System Improvement of a Frequency Modulated Continuous Wave (FMCW) Coherent LiDAR
D.Z. Yang, K.Y. Tao, X.M. Liu and Y.T. Dong
The carrier leakage and transmitting light’s nonlinearity always exist in frequency modulated continuous wave (FMCW) coherent LiDAR systems with the optical isolation by circulator. In order to reduce the leakage and decrease the influence of transmitting light’s nonlinearity to the beat frequency signal (BFS), the mathematical model of BFS simultaneously influenced by them is derived, in addition, the optimized configuration utilizing a twin-core fiber as the optical isolation is proposed and the high-order nonlinearity of BFS is compensated. The system simulations and experiments are carried out with the results that were consistent with those of theoretical analysis. The relative errors of velocity and range measurement are less than 2%.
Keywords: LiDAR, frequency-modulated continuous-wave (FMCW), coherent, carrier leakage, nonlinearity, beat frequency signal, twin-core fiber