Frequency-modulated continuous wave (FMCW) LiDAR can achieve long-distance and high-precision measurement, and the ranging error mainly comes from the nonlinearity of the laser frequency sweep. In this study, a high-precision silicon-integrated FMCW LiDAR is proposed. An equal frequency hypercube network is established by the stable free spectral range (FSR) of the microresonator to calibrate the nonlinearity of FMCW, and the distance matrix is obtained by analyzing the phase difference matrix of the FMCW signal. A standard length-based microresonator FSR calibration scheme is used to further improve the LiDAR accuracy. The feasibility of the scheme is verified by ranging and three-dimensional (3D) imaging. The ranging is carried out indoors and outdoors. In the indoor environment of a distance of 4 m, the minimum Allan deviation is 65 nm at 10.24 s. In the outdoor environment, the minimum Allan deviation at 438 m is 420 nm at 10.24 s. The 3D imaging can reconstruct the spatial point cloud of the objects and identify the spatial targets. This scheme has good on-chip integration capability and can be further combined with lens-assisted beam steering and optical phased array, laying the foundation for compact, large bandwidth, long-range, and high-precision LiDAR.

Since the dispersive interferometry (DPI) based on optical frequency combs (OFCs) was proposed, it has been widely used in absolute distance measurements with long-distance and high precision. However, it has a serious problem for the traditional DPI based on the mode-locked OFC. The error of measurements caused by using the fast Fourier transform (FFT) algorithm to process signals cannot be overcome, which is due to the non-uniform sampling intervals in the frequency domain of spectrometers. Therefore, in this paper, we propose a new mathematical model with a simple form of OFC to simulate and analyze various properties of the OFC and the principle of DPI. Moreover, we carry out an experimental verification, in which we adopt the Lomb–Scargle algorithm to improve the accuracy of measurements of DPI. The results show that the Lomb–Scargle algorithm can effectively reduce the error caused by the resolution, and the error of absolute distance measurement is less than 12 μm in the distance of 70 m based on the mode-locked OFC.

We demonstrate an arbitrary distance measurement method by chirped pulse spectrally interferometry (CPSI) using femtosecond optical frequency comb (OFC). In this paper, the chirped fiber Bragg grating (CFBG) is used to investigate the mapping relationship between displacement and the center frequency of the chirped spectral interferogram. We overcome the direction ambiguity of dispersive interferometry (DPI) ranging and expand the range of distance measurement to 18 cm. Besides, we achieve a full range of dead-zone free ranging by introducing a variable optical delay line (VODL). And through principles simulation and experiment, it is demonstrated that the measurement accuracy is 12 µm in comparison with an incremental He–Ne laser interferometer and the minimum Allen deviation is 52 nm at an average time of 1.76 ms. Similarly, in the experiment with long-distance of ∼30m, the accuracy reaches 20 µm, and 2.51 µm repeatability is achieved under harsh environment.

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