Simulation and analysis of electro-optic tunable microring resonators in silicon thin film on lithium niobate

Huangpu Han,Bingxi Xiang

doi:10.1038/s41598-019-42818-2

Abstract

Silicon thin film on lithium niobate combines the advantages of electronic properties of silicon and optical properties of lithium niobate, making it an ideal platform for high-density integrated optics. In this paper, we present an electro-optic tunable microring resonator in silicon thin film on lithium niobate operating at wavelengths of approximately 1.55 μm. The single-mode conditions, optical power distribution, mode profiles, and propagation losses of silicon waveguides are discussed and compared systematically. Quality factor, free spectral range, and bending losses of silicon microring resonators as different radii for different gap sizes between channel and ring waveguides are analyzed in detail. The bending loss and free spectral range decreased with increasing bending radius while the quality factor increased with increasing radius and gap size. The transmission spectrum of microring with radius R = 10 μm was tuned using the electro-optic effect. The key issues affecting the electro-optic effect, such as silicon film thickness and electric field strength, are discussed. This study is helpful for the understanding of microring structures in silicon thin film on lithium niobate, as well as for the fabrication of high-performance and multifunctional photonic integrated devices.

Highlights

As a semiconductor, silicon (Si) chips demonstrate superb advantages in the integrated electronics industry[1]
microring resonators (MRRs) in silicon on insulators (SOIs)[14,15], LN on insulators (LNOIs)[16,17,18], and LN on SOIs19,20 have been reported in the literature
In the work described in this paper, we present a compact and highly linear MRR-based Si thin film bonded to a z-cut LN cladding layer

Summary

Introduction

Silicon (Si) chips demonstrate superb advantages in the integrated electronics industry[1]. Single crystal silicon does not show a linear electro-optic effect, which limits its application in the field of integrated optics. Lithium niobate (LiNbO3, LN) is a widely used electro-optic crystal in integrated optics due to its high Pockel’s coefficients (γ33 = 31.2 pm/V)[2,3]. LN has high Pockel’s coefficients, but LNOI-based resonators have not been integrated into the foundry Si photonics fabrication process popularized over the last decade. In the work described in this paper, we present a compact and highly linear MRR-based Si thin film bonded to a z-cut LN cladding layer. The great potential of Si thin film on LN cladding layer for ultra-compact integrated optics is shown on simulations of electro-optic tunable MRRs at different silicon thicknesses and electric field strengths

Methods

Results

Conclusion