Electrically controllable laser frequency combs in graphene-fibre microresonators
Chenye Qin, Kunpeng Jia, Qianyuan Li, Teng Tan, Xiaohan Wang, Yanhong Guo, Shu‐Wei Huang, Yuan Liu, Shining Zhu, Zhenda Xie, Yunjiang Rao, Baicheng Yao
Abstract
Laser frequency combs emitting ultrafast pulses of light, at equidistantly discrete frequencies, are cornerstones of modern information networks. In recent years, the generation of soliton combs in microcavities with ultrahigh-quality factors has established microcombs as out-of-laboratory tools. However, the material and geometry of a laser cavity, which determine comb formation, are difficult to electrically tune. Such dynamic control can further enrich the diversity of comb outputs and help to actively stabilize them. Here we demonstrate electrically controllable laser frequency combs in a heterogeneous graphene-fibre microcavity. By altering the Fermi level of atomically thick graphene, we simultaneously demonstrate the tunable absorption, controllable Q -factor, and fast optoelectronic feedback stabilization. Thus, we can use this device to produce mode-locked laser combs with tunable repetition rates, controllable wavelengths, and self-stabilized phase noise down to −120 dBc Hz −1 at 10 kHz. The span of the combs can be further broadened to more than half an octave through convenient supercontinuum amplification. Combining phase-locking techniques and single-atomic-layer optoelectronics, this study provides knowledge for achieving a high-repetition rate optical frequency comb on fibre.