The team's work on "High-speed electro-optic modulation in topological interface states of a one-dimensional lattice" has been accepted and published by "Light: Science & Applications." This work was supported by the National Key Research and Development Program (2019YFB2203601) and the National Natural Science Foundation of China (62035016/61975115/61835008).
The PhotonMind team at Shanghai Jiao Tong University, in collaboration with Professor Yonghui Tian from Lanzhou University and Professor Jianwen Dong from Sun Yat-sen University, proposed a highly compact, low-power, and high-bandwidth electro-optic modulator based on one-dimensional topological lattice waveguides on a lithium niobate thin film platform loaded with silicon nitride. The principle behind this modulator involves the generation of one-dimensional topological boundary state modes. Thanks to the strong confinement and robustness provided by the one-dimensional topological lattice waveguides, this topological photon microcavity is short in length and strictly operates in a single mode, avoiding issues associated with multi-mode control. Experimental results demonstrate that this high-speed electro-optic modulator boasts an ultra-low energy consumption of 5.4 fJ/bit and a large bandwidth of 104 GHz, all while having a compact length of only 140 μm.
Abstract:Electro-optic modulators are key components in data communication, microwave photonics, and quantum photonics. Modulation bandwidth, energy efficiency, and device dimension are crucial metrics of modulators. Here, we provide an important direction for the miniaturization of electro-optic modulators by reporting on ultracompact topological modulators. A topological interface state in a one-dimensional lattice is implemented on a thin film lithium niobate integrated platform. Due to the strong optical confinement of the interface state and the peaking enhancement of the electro-optic response, a topological cavity with a size of 1.6 × 140 μm2 enables a large modulation bandwidth of 104 GHz. The first topological modulator exhibits the most compact device size compared to reported LN modulators with bandwidths above 28 GHz, to the best of our knowledge. 100 Gb/s non-return-to-zero and 100 Gb/s four-level pulse amplitude modulation signals are generated. The switching energy is 5.4 fJ/bit, owing to the small electro-optic mode volume and low capacitance. The topological modulator accelerates the response time of topological photonic devices from the microsecond order to the picosecond order and provides an essential foundation for the implementation of large-scale lithium niobate photonic integrated circuits.