Folded Heterogeneous Silicon and Lithium Niobate Mach-Zehnder Modulators with Low Drive Voltage.

Shihao Sun,Xinlun Cai,Xian Zhang,Lidan Zhou,Mengyue Xu,Siyuan Yu,Shengqian Gao,Mingbo He,Lin Liu

doi:10.3390/mi12070823

Abstract

Optical modulators were, are, and will continue to be the underpinning devices for optical transceivers at all levels of the optical networks. Recently, heterogeneously integrated silicon and lithium niobate (Si/LN) optical modulators have demonstrated attractive overall performance in terms of optical loss, drive voltage, and modulation bandwidth. However, due to the moderate Pockels coefficient of lithium niobate, the device length of the Si/LN modulator is still relatively long for low-drive-voltage operation. Here, we report a folded Si/LN Mach–Zehnder modulator consisting of meandering optical waveguides and meandering microwave transmission lines, whose device length is approximately two-fifths of the unfolded counterpart while maintaining the overall performance. The present devices feature a low half-wave voltage of 1.24 V, support data rates up to 128 gigabits per second, and show a device length of less than 9 mm.

Highlights

By harnessing the mature CMOS foundries, silicon photonics based on silicon-oninsulator (SOI) platforms promises the low cost and high volume production for photonic integrated circuits (PICs) [1,2]
We have demonstrated folded Mach–Zehnder modulators (MZMs) based on a heterogeneous integrated silicon and lithium niobate platform using meandering optical waveguides and
The devices show reduced device length while maintaining the overall performance of the non-folded counterparts. Since both of the optical waveguides and traveling wave electrode (TWE) undergo two U-turns, the device length is reduced to approximately two-fifths of the original value

Summary

Introduction

By harnessing the mature CMOS foundries, silicon photonics based on silicon-oninsulator (SOI) platforms promises the low cost and high volume production for photonic integrated circuits (PICs) [1,2]. This makes it a leading technology for future optical transceivers in both short-reach and long-haul optical communication links, in which high-speed, low-drive-voltage, and low-loss modulators are crucial components [3,4]. The free-carrier effect has intrinsic limitations in modulation bandwidth, optical loss and nonlinear response [5,6,7,8,9]. Tremendous efforts have been made toward heterogeneously integrating materials with strong electro-optic effects onto the silicon photonics platform, including graphene [10], electro-optic (EO) polymers [11], indium phosphide (InP) [12], and barium titanate (BTO) [13]

Methods

Results

Conclusion