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• Photonics Research
• Vol. 10, Issue 2, 02000535 (2022)
Weiqiang Xie1、2、†, Chao Xiang1、†, Lin Chang1, Warren Jin1, Jonathan Peters1, and John E. Bowers1、*
Author Affiliations
• 1Department of Electrical and Computer Engineering, University of California, Santa Barbara, Santa Barbara, California 93106, USA
• 2Current address: Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
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Weiqiang Xie, Chao Xiang, Lin Chang, Warren Jin, Jonathan Peters, John E. Bowers. Silicon-integrated nonlinear III-V photonics[J]. Photonics Research, 2022, 10(2): 02000535 Copy Citation Text show less

Abstract

Mainstream silicon photonic integrated circuits are based on compact and low-loss silicon-on-insulator (SOI) waveguide platforms. However, monolithic SOI-based photonics provides only a limited number of functional device types. Here, to extend the on-chip capabilities, we propose a general heterogeneous integration approach to embed highly nonlinear III-V (AlGaAs) photonics into the SOI platform. We develop low-loss AlGaAs-on-SOI photonic circuits with integrated Si waveguides and showcase sub-milliwatt-threshold ($∼0.25 mW$) Kerr frequency comb generation in ultrahigh-$Q$ AlGaAs microrings ($Q$ over $106$) at the telecom bands. Our demonstration complements existing mature Si photonics technology with efficient nonlinear functionalities provided by III-V and propels conventional Si photonics into emerging nonlinear photonic applications towards fully chip-based nonlinear engines.

1. INTRODUCTION

Silicon photonics based on silicon-on-insulator (SOI) substrates has been rapidly growing over the past two decades, providing various on-chip passive/active photonic functionalities (waveguide-based passive components, modulators, photodetectors, etc.) by taking advantage of mature planar CMOS technology, leading to the development of Si photonic integrated circuits (PICs) [14]. Moreover, III–V-on-Si (III-V/Si) heterogeneous integration techniques have been developed to address the laser source issue for Si photonics and have now been adopted in scalable state-of-the-art CMOS-compatible processes [5]. Today, Si photonics is playing a leading role in the community of integrated photonics and has found applications in a large number of areas including optical interconnects [6,7], telecommunications [8], computing [9], and so on [10]. Meanwhile, significant progress spanning the last decade on integrated nonlinear photonics has emerged as a new paradigm for both nonlinear optics research and applications. An intriguing offering of integrated nonlinear photonics is its capability of generating new classes of coherent, ultra-broadband light sources (i.e., microcombs) in nonlinear waveguides [11,12], which is not attainable from linear photonics systems. Microcombs have triggered widespread use of chip-scale nonlinear devices in applications [13] including ultrahigh-capacity coherent telecommunications [14,15], optical frequency synthesis [16], optical atomic clocks [17], quantum optics [18], etc. In the past few years, significant technological advances have enabled ultralow-loss nonlinear waveguides and ultrahigh-quality-factor ($Q$-factor) microresonators [1923]. Those breakthroughs have essentially allowed high-efficiency nonlinear processes operating at dramatically reduced power levels of milliwatts or sub-milliwatts [19,21,2428], eliminating bulky optical equipment such as benchtop pump lasers and amplifiers. The power requirements in nonlinear waveguides are now compatible with co-integrated III-V/Si pump lasers on a single chip [29], which represents a key step towards harnessing the on-chip nonlinear properties from individual and passive-only nonlinear devices, to mass-manufactured system-level architectures and application developments.

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Weiqiang Xie, Chao Xiang, Lin Chang, Warren Jin, Jonathan Peters, John E. Bowers. Silicon-integrated nonlinear III-V photonics[J]. Photonics Research, 2022, 10(2): 02000535