Active passive monolithic platforms in Si3N4 technology

Abstract

Integrated photonic platforms such as the SOI platform, the InP platform and the Si3N4 platforms have their own advantages and limitations. To achieve more diverse functionalities on a photonic chip, the combination of different material platforms is extremely important. This is generally carried out by either hybrid integration, heterogeneous integration or monolithic integration. The goal of this thesis is to develop generic integrated platforms and building blocks that enable various active-passive photonic integrations based on the Si3N4 platform. Chapter 1 reviewed the challenges, integration schemes in photonic integrated circuits (PIC), and recent advances in the Si3N4 PICs. Benefiting from excellent optical features of the Si3N4, i.e., the low-loss and large transparency window (0.4–2.35 µm), in Chapter 2, we investigated passive building blocks with optical designs, providing favorable performance of individual components in the Si3N4 platform. Then in Chapter 3, we demonstrated the hybrid integration and monolithic integration between the Si3N4 and polymer material with high-performance optical couplings. In order to realize the active-passive integration in the Si3N4 platform, in Chapter 4, we developed a double-layer photonic platform with standardized processes and good overlay by monolithic integration between the Si3N4 and rare-earth-ion doped Al2O3 material, showing great potentials of scalable and tolerant integrations of active functionalities in the Si3N4 platform. Chapter 5 demonstrated the first application of the double-layer platform, i.e., the integrated Al2O3:Er3+-Si3N4 amplifiers. A novel gain characterization methodology is introduced and high optical gain (~18 dB) has been achieved. Overall, the work in this thesis provides advances in understanding the characteristics of different integration platforms, especially in the development of the double-layer platforms for the active-passive integration of the Si3N4 and rare-earth-ion doped Al2O3, and the integrated Al2O3:Er3+-Si3N4 amplifiers. The investigations pave the way of various applications based on active-passive integration of the Si3N4 and rare-earth-ion based materials.