Photonics uses light rather than electrons to perform a wide variety of applications. Silicon photonics, in particular, has gained a lot of interest in the last few decades due to its ability to control light at chip-scale. Although the field has its roots in the telecommunications industry, it has expanded to many new applications such as sensing, spectroscopy, nonlinear optics, quantum optics, opto-mechanics, and even neuroscience. Nonlinear optics has been greatly benefited from the chip-scale devices. Because light can be tightly confined inside these devices, nonlinear effects can be strongly enhanced. In recent years, there has been progress in development of microresonator-based Kerr frequency comb, these frequency combs have triggered a large number of applications, including in atomic clocks, optical communications, dual-comb spectroscopy, frequency synthesizers and sensing. However, simultaneously achieving ultra low-loss and high confinement which is critical for nonlinear optics remains a challenge.

In this talk, I will set out to address this challenge in order to enable new applications. Silicon nitride is chosen as the material platform here. It allows us to achieve ultra low-loss and observe nonlinear processes with record-low power. I will start with an overview of the loss origins and general fabrication process of most photonic devices. A more detailed explanation of critical process steps are presented. Then I will talk about applications utilizing ultra low-loss silicon nitride platform such as frequency combs generation, narrow linewidth lasers, on-chip tunable delay line and so on. Finally, I will conclude with a discussion of possible research avenues one could take to build upon work presented here.