State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
Hong-Xuan Liu
State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
Hao-Chen Xu
State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
Yi-Shu Huang
State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
Huan Li
State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
Ze-Jie Yu
State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Zijingang Campus, Hangzhou 310058, China; Jiaxing Key Laboratory of Photonic Sensing & Intelligent Imaging, Jiaxing 314000, China; Intelligent Optics & Photonics Research Center, Jiaxing Research Institute Zhejiang University, Jiaxing 314000, China
Liu Liu
State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Zijingang Campus, Hangzhou 310058, China; Ningbo Research Institute, Zhejiang University, Ningbo 315100, China; Jiaxing Key Laboratory of Photonic Sensing & Intelligent Imaging, Jiaxing 314000, China; Intelligent Optics & Photonics Research Center, Jiaxing Research Institute Zhejiang University, Jiaxing 314000, China
Yao-Cheng Shi
State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Zijingang Campus, Hangzhou 310058, China; Ningbo Research Institute, Zhejiang University, Ningbo 315100, China; Jiaxing Key Laboratory of Photonic Sensing & Intelligent Imaging, Jiaxing 314000, China; Intelligent Optics & Photonics Research Center, Jiaxing Research Institute Zhejiang University, Jiaxing 314000, China
Dao-Xin Dai
State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Zijingang Campus, Hangzhou 310058, China; Ningbo Research Institute, Zhejiang University, Ningbo 315100, China; Jiaxing Key Laboratory of Photonic Sensing & Intelligent Imaging, Jiaxing 314000, China; Intelligent Optics & Photonics Research Center, Jiaxing Research Institute Zhejiang University, Jiaxing 314000, China; Corresponding author at: Zhejiang University, State Key Laboratory for Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zijingang Campus, Hangzhou 3100058, China.
A lithium-niobate-on-insulator (LNOI) electro-optic (EO) modulator based on a 2 × 2 FP-cavity was designed and realized with an ultra-compact footprint and an ultra-high bandwidth. A comprehensive analysis on the present LNOI FP-cavity modulator was conducted to reveal the dependence of modulation bandwidth and modulation efficiency on the cavity Q-factor and the operation wavelength detuning to the resonance. In particular, the 2 × 2 FP cavity was designed to achieve an optimal Q factor by reducing the reflectivity of reflectors and the cavity length, thus reducing the photon lifetime in the cavity . An ultra-short effective cavity length of only∼ 50 µm was achieved for the designed LNOI FP-cavity modulator, with itsfootprint being as compact as ∼ 4 × 500 µm2. It was demonstrated theoretically that the modulation bandwidth could be improved significantly to be over 200 GHz by utilizing the peaking enhancement effect. The fabricated device exhibited an excess loss of ∼ 1 dB and an extinction ratio of ∼ 20 dB in experiments, while the measured 3-dB bandwidth was higher than 110 GHz (beyond the maximal range of the facilities in experiments). Up till now, to our best knowledge, this has been the first LNOI microcavity modulator with a bandwidth higher than 110 GHz. Finally, high-quality eye-diagrams of 100 Gbps on-off keying (OOK) and 140 Gbps 4-pulse amplitude modulation (PAM4) signals were demonstrated experimentally, and the energy consumption for the OOK signals was as low as 4.5 fJ/bit.
