Heterogeneous integrated phase modulator based on two-dimensional layered materials

Abstract

Silicon nitride, with ultralow propagation loss and a wide transparency window, offers an exciting platform to explore integrated photonic devices for various emerging applications. It is appealing to combine the intrinsic optical properties of two-dimensional layered materials with high-quality optical waveguides and resonators to achieve functional devices in a single chip. Here we demonstrate a micro-ring resonator-based phase modulator integrated with few-layer MoS 2 . The ionic liquid is employed directly on the surface of MoS 2 to form a capacitor configuration. The effective index of the composite MoS 2 – SiN waveguide can be modulated via adjusting bias voltages to achieve different charged doping induced electro-refractive responses in MoS 2 film. The maximum effective index modulation of the composite MoS 2 – SiN waveguide can be achieved to 0.45 × 10 − 3 . The phase tuning efficiency is measured to be 29.42 pm/V, corresponding to a V π L of 0.69 V·cm. Since the micro-ring resonator is designed near the critical coupling regime, the coupling condition between the bus waveguide and micro-ring resonator can also be engineered from under-coupling to over-coupling regime during the charged doping process. That can be involved as a degree of freedom for the coupling tailoring. The ability to modulate the effective index with two-dimensional materials and the robust nature of the heterostructure integrated phase modulator could be useful for engineering reliable ultra-compact and low-power-consumption integrated photonic devices.