Abstract
We demonstrate efficient coherence enhancement of a chirped distributed feedback (DFB) laser for frequency-modulated continuous-wave (FMCW) reflectometry. Both sweep nonlinearity and broadband stochastic frequency noises during the laser chirp are efficiently suppressed by a composite feedback loop. The residual frequency error relative to a perfect linear chirp is shown to be about 89 kHz for a laser chirp of 50 GHz in 100 ms, compared with 44 MHz with the loop open. The broadband frequency noise suppression of the frequency-swept laser greatly improves its coherence, leading to a higher signal-to-noise ratio and a significantly extended measurement range in FMCW reflectometry ranging. We demonstrate a 2 mm transform-limited spatial resolution at a range window of 50 m and a 17.5 cm spatial resolution at an extended measurement range of 750 m, which is about 15 times the intrinsic laser round-trip coherence length.
© 2015 Optical Society of America
Full Article | PDF ArticleMore Like This
Jie Qin, Ling Zhang, Weilin Xie, Ran Cheng, Zhangweiyi Liu, Wei Wei, and Yi Dong
Opt. Express 27(14) 19359-19368 (2019)
Weilin Xie, Qian Zhou, Fabien Bretenaker, Zongyang Xia, Hongxiao Shi, Jie Qin, Yi Dong, and Weisheng Hu
Opt. Lett. 41(13) 2962-2965 (2016)
Thomas DiLazaro and George Nehmetallah
Opt. Express 25(3) 2327-2340 (2017)