Ultrafine electro-optical frequency comb based on cascade phase modulation with cyclic frequency shifting
Changhe Wang, Yuxin Sun, Qilai Zhao, Changsheng Yang, Chun Zeng, Zhouming Feng, Yu Zhang, Li Li, Kaijun Zhou, Xiaoming Wei, Zhongmin Yang, Shanhui Xu- Atomic and Molecular Physics, and Optics
An ultrafine electro-optical frequency comb (EOFC) with plentiful comb teeth is demonstrated. Adopting a single-frequency fiber laser as a light source, cascade phase modulation based on a sinusoidal signal and a frequency-time transformation (FTT) signal is executed to generate the EOFC with high fineness. Meanwhile, a cyclic fast frequency shifting strategy is introduced to boost the number of comb teeth and the bandwidth of the EOFC. As a result, an EOFC with 12600 comb lines covering a broad bandwidth from −6.3 GHz to 6.3 GHz is established, corresponding to an ultrafine comb space of 1 MHz. Moreover, the power fluctuation of a comb tooth is less than 0.5 dBm. This state-of-the-art EOFC has significant potential in the field of precision spectroscopy.