Linearizing Optical Frequency Chirp of a DFB Laser by Optimizing the Modulation Waveform Using Resampling Technique for FMCW LiDAR

Optical frequency chirp of a distributed feedback (DFB) laser is linearized for high ranging resolution and high accurate FMCW optical ranging system. The linearization method is based on the resampling technique. The modulation waveform of the DFB laser for the optical frequency chirp is modified so that the beat frequency of the interference signal is constant in time. The modulation waveform is sampled with the interference signal generated in an auxiliary interferometer, and then, the sampled waveform is used as a new modulation waveform of the DFB laser. As a result, the optical frequency is linearly chirped. By repeating the process several times, the optical frequency is successfully linearized up to 97-m optical fiber as the target device. The DFB laser with linearized optical frequency chirp is used as the light source of the FMCW light detection and ranging (LiDAR), and fine profiling results of a building about 50 m away and about 105 m away are realized.