Thin-Film Lithium Niobate Modulators With Angled Electrodes for Improved Modulation Efficiency

Low-power electro-optic modulators are crucial devices for applications such as data center communications. In this work, we report a design featuring a traveling wave electrode with a sidewall angle and an optical slot waveguide to reduce the driving voltage of an electro-optic modulator. The design of our electro-optic modulator is based on matured semiconductor processing technology, which is commonly used in the fabrication of optical devices. Through the optimization of the angle of the electrode sidewall, the electric field concentration near the optical waveguide is strongly enhanced, and therefore the overlap between the electric field and optical field is increased. We achieve a voltage-length product of 1.48 V$\cdot$cm and a 3-dB modulation bandwidth of over 200 GHz. Our results demonstrate that the angled electrode design exhibits superior performance in terms of increased modulation efficiency and reduced electrode size compared to traditional traveling wave electrodes. This approach has the potential to be extended to electro-optic modulators of other structures.