Phase modulators in hybrid silicon and lithium niobate thin films

Abstract

The hybridization of mono-crystalline silicon and lithium niobate thin films (Si-LNOI) can combine the physical properties of Si and the optical properties of LN, and it has emerged as a new material platform for integrated photonics. In this paper, phase modulators in Si-LNOI were demonstrated. First, the phase modulator was designed. According to the simulation, the Si loading strip waveguide had a small mode area due to the large refractive index of Si. This allowed a small electrode gap that resulted in enhancement of the overlap of the optical field and the electrostatic field, and the VπL of the phase modulator could be as small as 3.3 V·cm. Second, phase modulators with a Si loading strip waveguide with a top width of 0.5 μm were fabricated by plasma etching, and the VπL of the phase modulator was measured to be 4.74 V·cm. This study provides useful information for the devices in the Si-LNOI.