Zheng Yan, Li Jilong, Dai Yitang, Yin Feifei, Xu Kun
Opt Lett. 2018 Jan 15;43(2):194-197. doi: 10.1364/OL.43.000194.
We demonstrate a novel real-time Fourier transformation scheme with megahertz-level resolution realized by bandwidth magnification of radio frequency (RF) signals. Before the frequency-to-time mapping, the RF signal is modulated on an optical frequency comb, and then extracted by a Vernier comb filter. As a result, RF components can be separated in the spectrum with a greatly magnified optical bandwidth. Thus, even with limited dispersion provided by an ordinary optical fiber, the frequency-dependent pulses can be distinguished in the time domain. Experimentally, the RF signal with the frequency difference of 60 MHz is separated by around 123 ps in the time domain, equivalent to the dispersion of 1975.5 ps/GHz (2.47×10 ps/nm), while the physical dispersion is 1500 ps/nm. Thus, based on the bandwidth magnification of signals, the dispersion is equivalently amplified by 165 times.
我们展示了一种新颖的实时傅里叶变换方案，该方案通过射频（RF）信号的带宽放大实现了兆赫兹级分辨率。在频率到时间映射之前，RF信号在光学频率梳上进行调制，然后通过游标梳状滤波器提取。结果，RF分量可以在具有大大放大的光学带宽的频谱中分离。因此，即使普通光纤提供的色散有限，频率相关的脉冲也可以在时域中区分出来。实验上，频率差为60 MHz的RF信号在时域中被分离约123 ps，相当于1975.5 ps/GHz（2.47×10 ps/nm）的色散，而物理色散为1500 ps/nm。因此，基于信号的带宽放大，色散等效地放大了165倍。
