作者：Chenglong Feng, Yong Zhang*, Jian Shen, Zihan Xu, Yihang Dong, Xuecheng Fu, Ying Wang, Lu Sun, Xuetao Gan, and Yikai Su*
摘要：Integrated tunable optical filters are essential components in photonic signal processors, telecom systems, sensors, and quantum optical devices. Two of the most important features of a tunable filter are its dimensions and power consumption. Herein, we present the design and experimental validation of an on-chip optical filter composed of a one-dimensional topological photonic crystal cavity based on a hybrid integrated lithium tantalite-silicon platform. We demonstrate that the strong optical confinement of the boundary state allows the fabrication of a tunable filter with an ultra-compact size of 1.14 × 75 μm2. Moreover, lithium tantalite has excellent electro-optic properties and enables ultra-low-power wavelength tuning of the topological boundary state. The measured power consumption and tuning efficiency of the device are 0.0218 nW pm−1 and 6.64 pm V−1, respectively. The anisotropy of thin-film lithium tantalite is verified by evaluating its tuning efficiency at different optical angles. The device can compensate for thermally induced refractive index changes around 20 °C, exhibiting operational robustness. High-speed transmission experiments confirm the stability of the developed tunable filter. This optical filter implements a topological structure with a compact size and can potentially be applied in on-chip quantum optics, nonlinear optics, and optical sensing.
出版源：Laser & Photonics Reviews
