Enhanced Velocity Measurement of Lidar by Optical Parametric Assisted Frequency Modulation

A novel approach is proposed to enhance the velocity measurement range of frequency-modulated continuous-wave (FMCW) Lidar. By virtue of optical parametric assisted frequency modulation (OPAFM) method, the available range of velocity measurement can be double. In our experimental demonstration, the chirp rate of a frequency sweeping light is increased from 6.40
$\text{GHz}/\mu\mathrm{s}$
to 12.80
$\text{GHz}/\mu\mathrm{s}$
. Hence, the maximum measurable velocity for a target at 5.2 m can be improved from 2.13 m/s to 4.41 m/s.