▎ 摘　　要

We propose a novel continuously tunable delay line in X-cut lithium niobate thin film driven by graphene electrodes, featuring low power consumption and low half-wave voltage-length product. The use of the graphene electrodes combined with the air slots makes the device quite low power consumption. Our designed device, which has a footprint of 8.9 mm x 1.9 mm, is capable of providing a continuously tunable delay range from 0 to 100 ps with minimum 3 dB bandwidth of >20 GHz. By optimizing the width of the waveguide core and the distance between the graphene and the waveguide core, we can obtain the low power consumption and low voltage - length product V pi L = 1.12 V center dot cm at 1550 nm when w = 2 mu m and d = 0.3 mu m. In addition, the graphene electrode has negligible light absorption with w = 2 mu m and d = 0.3 mu m, the switching power is 151 mW without air slots, and the switching power is 95.36 mW with air slots etching depth of 5.3 mu m formed on both sides of the waveguides. And further, the air slots formed on both sides and at the bottom of the waveguides make a low switching power of 2.85 mW.