Linear frequency sweeping control for LiDAR application

A FMCW(Frequency-Modulated Continuous Wave) LiDAR recently attracts a lot of interest because it is much robust to harsh environmental conditions and sun light because it takes the advantage of the wave properties of the laser. It measures the distance by calculating the optical interference frequency generated by interfering a reference beam that is modulated with a received beam that is reflected from an object. A tunable laser can be used for modulating the frequency of the laser beam. However, it is difficult to have a linear frequency modulation by the applied current to the tunable laser. For example, when the current is increased proportionally, the interference frequency varies with respect to time. Hence, a linear frequency modulating control of the tunable laser is proposed to improve the distance accuracy by generating the linear frequency modulation.