Generation of linear frequency modulation laser source with broadband narrow linewidth using optical phase modulator

Mengmeng, 许蒙蒙 Xu; Yu, 周煜 Zhou; Jianfeng, 孙剑锋 Sun; Zhiyong, 卢智勇 Lu; Chenzhe, 劳陈哲 Lao; Hongyu, 贺红雨 He; Yuexin, 李跃新 Li

doi:10.3788/irla202049.0205004

Cited by 2 publications

(1 citation statement)

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“…The transmitted signal is a triangular linear FMCW generated by a tunable laser source. The carrier signal is generated by a seed laser source, and under the excitation of a Radio Frequency (RF) source, an electro-optic modulator is used to modulate the carrier signal into a FMCW laser signal [24]. To ensure that SAL can achieve high signal-to-noise ratio imaging of remote targets, it is necessary to generate a sufficiently high power signal.…”

Section: Fmcw Sal Systemmentioning

confidence: 99%

Synthetic Aperture Ladar Motion Compensation Method Based on Symmetric Triangle Linear Frequency Modulation Continuous Wave Segmented Interference

Shi,

Li,

Dong

et al. 2024

Remote Sensing

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Synthetic Aperture Ladar (SAL) is a sensor that combines laser detection technology with synthetic aperture technology to achieve ultra-high-resolution imaging. Due to its extremely short wavelength, SAL is more sensitive to motion errors. The micrometer-level motion will affect the target’s azimuth focus. This article proposes an SAL motion compensation method based on Symmetric Triangular Linear Frequency Modulation Continuous Wave (STLFMCW) segmented interference, utilizing the characteristics of a triangular wave, to solve the problem of target azimuth defocusing. This article first establishes an STLFMCW echo signal model based on the SAL system under the influence of motion errors. Secondly, the radial velocity gradient along the azimuth direction is extracted using the triangular-wave-positive and -negative frequency modulation signals segmented interference method. Then, for the initial phase wrapping problem, the frequency spectral cross-correlation method is used to accurately estimate the initial radial velocity error. The radial velocity gradient is integrated along the azimuth to obtain the platform motion trajectory. Finally, the compensation functions are constructed to complete the echo Range Cell Migration (RCM) correction and residual phase compensation, resulting in a focused SAL image. This article verifies the practical effect of this method in eliminating motion errors using only one-period STLFMCW signal through simulation and real experiments. The quantitative results show that compared with the traditional method, the proposed method reduces the azimuth Peak Sidelobe Ratio (PSLR) by 8dB and the Integrated Sidelobe Ratio (ISLR) by 9 dB. This method has significant improvements and is of great significance for high-resolution FMCW SAL imaging.

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Section: Fmcw Sal Systemmentioning

confidence: 99%