Heterogeneous integration of silicon nitride and amorphous silicon carbide photonics

TL;DR

This paper demonstrates the monolithic integration of amorphous silicon carbide with silicon nitride photonics, combining their advantages for enhanced performance, tunability, and flexible coupling strategies in integrated photonic applications.

Contribution

It introduces a novel heterogeneous integration method of a-SiC and SiN photonics, achieving low interconnection loss, high integration density, and significantly improved thermo-optic tuning efficiency.

Findings

Achieved 0.32 dB interconnection loss between a-SiC and SiN

Increased integration density by over 4,444 times

Realized 27 times higher thermo-optic tuning efficiency

Abstract

Amorphous silicon carbide (a-SiC) has emerged as a compelling candidate for applications in integrated photonics, known for its high refractive index, high optical quality, high thermo-optic coefficient, and strong third-order nonlinearities. Furthermore, a-SiC can be easily deposited via CMOS-compatible chemical vapor deposition (CVD) techniques, allowing for precise thickness control and adjustable material properties on arbitrary substrates. Silicon nitride (SiN) is an industrial well-established and well-matured platform, which exhibits ultra-low propagation loss, but it is suboptimal for high-density reconfigurable photonics due to the large minimum bending radius and constrained tunability. In this work, we monolithically combine a-SiC with SiN photonics, leveraging the merits of both platforms, and achieve the a-SiC/SiN heterogeneous integration with an on-chip interconnection loss of 0.32$\pm$0.10 dB, and integration density increment exceeding 4,444-fold. By implementing active devices on a-SiC, we achieve 27 times higher thermo-optic tuning efficiency, with respect to the SiN photonic platform. In addition, the a-SiC/SiN platform gives the flexibility to choose the optimal fiber-to-chip coupling strategy depending on the interfacing platform, with efficient side-coupling on SiN and grating-coupling on a-SiC platform. The proposed a-SiC/SiN photonic platform can foster versatile applications in programmable and quantum photonics, nonlinear optics, and beyond.