Frequency-Modulated Chirp Signals for Single-Photodiode Based Coherent LiDAR System
| Autor: | Wenting Yi, Eric Sillekens, Zhe Li, Zhixin Liu, Polina Bayvel, Zichuan Zhou, Robert I. Killey, Filipe Ferreira, Thomas Gerard, Lidia Galdino, Callum Deakin |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Journal of Lightwave Technology. 39:4661-4670 |
| ISSN: | 1558-2213 0733-8724 |
| DOI: | 10.1109/jlt.2021.3081255 |
| Popis: | In this paper, we investigate two categories of linear frequency-modulated chirp signals suitable for single-photodiode based coherent light detection and ranging (LiDAR) systems, namely, the frequency-modulated continuous-wave (FMCW) single-sideband (SSB) signal and the amplitude-modulated double-sideband (DSB) signal, and compare their achievable receiver sensitivity performance. The DSB signal requires a simpler transmitter design, as it is real-valued and can be generated using a single-drive Mach-Zehnder modulator (MZM), while the SSB signal, which is frequency/phase modulated, requires an in-phase and quadrature modulator (IQM)-based transmitter. A theoretical analysis of direct-detection (DD) beating interference (BI) especially the local oscillator (LO) beating with itself, known as LO-LO BI, is presented. Both Monte Carlo simulations and experimental demonstrations are carried out. Good agreement between simulations and experiments is achieved. In comparison with the SSB system, the DSB signal-based system is affected by laser phase noise-induced power fluctuation, and also suffers a significant sensitivity penalty due to nonlinear LO-LO BI. A spectral guard band for mitigating LO-LO BI is necessary for the DSB signal, achieved at the expense of requiring a larger electrical bandwidth. In system tests with a delay line of 385 m, the SSB signal outperforms the DSB signal with a 10 dB better receiver sensitivity in the case with a guard band, and 25 dB better sensitivity without a guard band. |
| Databáze: | OpenAIRE |
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