基于异步射频信号驱动级联相位调制器产生平坦光学频率梳

Generation of Flat Optical Frequency Comb Based on Asynchronous RF-Signal-Driven Cascaded Phase Modulators

基于级联相位调制器(PM),设计并实现了一种梳线数量与梳线间距均可调谐的光学频率梳(OFC)产生方案。采用正弦型射频信号与其倍频信号分别驱动两级PM,并在第二级射频信号加入微小的频率偏移,得到了相位不敏感、平坦度高的OFC。梳线数量与平坦度由两级PM的调制指数调控。当频率偏移为第二级射频信号频率的10-5倍时,OFC的平坦度低于3dB。实验结果表明,产生OFC的梳线数量为7,9,11根,梳线间距分别为5.5GHz和7.5GHz,平坦度不超过2.4dB。

Based on cascaded phase modulators (PM), a scheme to generate a optical frequency comb (OFC) with adjustable comb number and comb spacing is proposed and experimentally demonstrated. The sinusoidal radio frequency (RF) signal and its double-frequency signal are used to drive the two cascaded PMs, respectively, simultaneously a small frequency offset is introduced in the second RF signal, and finally a phase-insensitive and high flatness OFC is obtained. The comb number and flatness are regulated by the modulation index of these two cascaded PMs. When the frequency offset is 10-5 times the frequency of the second RF signal, the flatness of this OFC is less than 3 dB. The experimental results show that the comb numbers are 7, 9, and 11, the comb spacing is 5.5 GHz and 7.5 GHz, and the flatness is smaller than 2.4 dB for the generated OFC.