Figure | Principle and performance of the cavity-dynamics enabled coherent ranging. (IMAGE)
Caption
Figure | Principle and performance of the cavity-dynamics enabled coherent ranging.a, Concept diagram of the cavity-dynamics enabled ranging system with enhanced resolution. Similar to the FMCW method, a tunable laser emits a frequency-swept beam, yet the backscattered light is reinjected into the laser resonator. The feedback light re-enters the laser cavity, interferes with the intracavity field, and generates interference signals and their harmonics. Top inset: schematic of the interaction between feedback light and intracavity-stimulated radiation. The harmonics multiply the phase sensitivity and thus enable high-resolution ranging. Bottom inset: simulated detection results of the conventional FMCW method and the proposed method for a local area of the target. b, Experimental setup of the system. c, Power spectra obtained in experiments. Harmonics up to the 13th are generated. d, Ranging results for a shiny target. The target performs a reciprocating motion with 0.1 mm steps. The results of the 13th harmonic clearly reconstruct the motion, whereas the fundamental wave fails to do so. e, Reconstructions in 3D imaging. The frequency-swept bandwidth is 15 GHz.
Credit
Yidong Tan et al.
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