A Novel Method of Measuring Instantaneous Frequency of an Ultrafast Frequency Modulated Continuous-Wave Laser
A Novel Method of Measuring Instantaneous Frequency of an Ultrafast Frequency Modulated Continuous-Wave Laser
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DOI：
10.3390/s20143834
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发表时间：
2020-07-01
期刊：
影响因子：
3.9
通讯作者：
Ge, Chunfeng
中科院分区：
文献类型：
--
作者：
Yang, Jiewei;Yang, Tianxin;Ge, Chunfeng
超快线性调频连续波 (FMCW) 激光器是一类特殊的 CW 激光器。线性 FMCW 激光器是许多传感应用的光源，特别是光检测和测距 (LiDAR)。然而，用于产生高质量线性 FMCW 光的系统在技术方法和机制方面是有限且多样的。由于缺乏线性调频连续激光器的表征方法，很难对同类产生系统进行比较和判断。我们提出了一种基于改进的相干光谱分析仪（COSA）和数字信号处理（DSP）方法来测量 FMCW 激光器瞬时频率和时间之间映射关系的新方案。我们的方法有可能以无限的扫描速率测量 FMCW 激光器的瞬时频率。在本文中，我们通过仿真和实验演示了如何使用这种新方法以 5000 THz/s 的大快速扫描速率精确测量 FMCW 激光器。我们通过实验发现该方法的不确定度小于100 kHz，如果引入频率反馈伺服系统来稳定本地连续激光器，则可以进一步提高。
Ultrafast linear frequency modulated continuous-wave (FMCW) lasers are a special category of CW lasers. The linear FMCW laser is the light source for many sensing applications, especially for light detection and ranging (LiDAR). However, systems for the generation of high quality linear FMCW light are limited and diverse in terms of technical approaches and mechanisms. Due to a lack of characterization methods for linear FMCW lasers, it is difficult to compare and judge the generation systems in the same category. We propose a novel scheme for measuring the mapping relationship between instantaneous frequency and time of a FMCW laser based on a modified coherent optical spectrum analyzer (COSA) and digital signal processing (DSP) method. Our method has the potential to measure the instantaneous frequency of a FMCW laser at an unlimited sweep rate. In this paper, we demonstrate how to use this new method to precisely measure a FMCW laser at a large fast sweep rate of 5000 THz/s by both simulation and experiments. We find experimentally that the uncertainty of this method is less than 100 kHz and can be improved further if a frequency feedback servo system is introduced to stabilize the local CW laser.