Chip-Scale Mass Manufacturable High-Q Silicon Microdisks

High-Q silicon microdisks are fundamental building blocks for on-chip photonic systems and have been well developed in past decades. However, the practical applications of high-Q silicon microdisks are facing a dilemma. The high-Q silicon microdisks are realized with electron-beam lithography and are hard to be massively fabricated. The standard photolithography usually generates microdisks with rough surfaces and cannot produce high Q resonators. This study addresses this challenge and reports a novel approach to fabricate chip-scale high-Q silicon microdisks with standard photolithography and an isotropic etching. While standard photolithography generates microscale roughness on the cavity boundary, these experimental results show that the following isotropic etching process can effectively smooth them. The ultimate surface roughness is even comparable to the microdisks that are fabricated with E-beam lithography. Consequently, the cavity Q factors are dramatically improved from a few thousand to more than a million. Compared with the conventional approach, this new technique is particularly intriguing. It can produce chip-scale high-Q silicon microdisks simultaneously for the first time. This research is a key step for mass fabrication of high-Q silicon microdisks, and it can boost the advances of silicon microdisks in a number of important applications, such as optical sensing, quantum optics, and integrated optical elements.