Distance and Velocity Characterizations Through Sampling Rate-Limited Main Interferometer in a Silicon Platform

• Published in: IEEE photonics journal 2024-06, Vol.16 (3), p.1-6
• Main Authors: Liao, Ting-Qing, Chang, Ting-Chia, Kang, Jhih-Jia, Hsu, Shih-Hsiang
• Format: Article
• Language: English
• Subjects: auxiliary interferometer; Continuous radiation; Data acquisition; Data points; Directional couplers; Distance measurement; Error correction; FMCW; Frequency modulation; Gratings; Hilbert transform; Hilbert transformation; Interferometers; Laser radar; LiDAR; Low noise; main interferometer; Optical imaging; Optical interferometry; Phase error; Resampling; Sampling; Silicon; Transforms
• ISSN: 1943-0655; 1943-0655; 1943-0647
• DOI: 10.1109/JPHOT.2024.3401550

The Hilbert transform can resample the signal to compensate for the nonlinear frequency sweeping phenomenon and precisely measure a distance and velocity through frequency-modulated continuous-wave (FMCW). Instead of an additional auxiliary interferometer, the direct Hilbert-transform resampling on the main interferograms of a silicon platform could correct the optical-source phase error to form compact light detection and ranging (LiDAR) systems in the characterizations of distances and velocities. More than two samples in an interferogram period will be a criterion in the sampling rate-limited FMCW distance tests. 876.86 cm and 18.058 cm ranging limits are demonstrated through 5 × 10 5 and 1x10 4 samples per second from the data acquisition, respectively, in a process-insensitive Mach-Zehnder directional coupler for FMCW-based LiDAR applications. The velocity of 200 mm per second was also illustrated in 5 × 10 5 samples per second. Moreover, the Hilbert-transform resampled on the main interferometer is superior to the peak-valley approach in the resampling data points, ranging accuracy, and low noise.