A stepped FM/CW lidar system using a dual parallel Mach-Zehnder modulator

A stepped frequency-modulated continuous-wave lidar system using a dual parallel Mach-Zehnder modulator with heterodyne detection is demonstrated. The lidar transmitter utilizes a modulation loop circuit composed of an electro-optic dual parallel Mach-Zehnder modulator and a fiber amplifier, as well as a tunable Fabry-Perot filter to generate a bandwidth-enhanced stepped frequency-modulated signal. In addition, a centroid algorithm is used in the receiver to process the signal with both high precision and high accuracy. The simulation results demonstrated that the ranging precision of the proposed lidar was 2.09 cm and the ranging accuracy was 0.16 cm. A validation experiment verified that the data obtained in the simulation had a modulation bandwidth of 4 GHz using a 200-MHz signal source. The improvements resulted in a frequency-modulated continuous-wave lidar system with high precision and accuracy by operating a modulated signal with a wider modulation bandwidth using signal sources with low bandwidth in a low-cost and compact structure.