Spectral shift and Q-change of circular and square-shaped optical microcavity modes due to periodic sidewall surface roughness

Temperature tunability of quantum emitter - cavity coupling in a photonic wire microcavity with shielded sidewall loss

Recent technological advancements have allowed to implement in solid-state cavity-based devices phenomena of quantum nature such as vacuum Rabi splitting, controllable single photon emission and quantum entanglement. For a sufficiently strong coupling between a quantum emitter and a cavity, large quality factors ($Q$) along with small modal volume ($V_{eff}$) are essential. Here we show that by applying a 5nm Al coating to the sidewalls of a submicrometer-sized Fabry-Pérot microcavity, the cavity $Q$ can be temperature-tuned from few hundreds at room temperatures to 2$\times$10$^5$ below 30~K.…

Measurements and modeling of atomic-scale sidewall roughness and losses in integrated photonic devices

Atomic-level imperfections play an increasingly critical role in nanophotonic device performance. However, it remains challenging to accurately characterize the sidewall roughness with sub-nanometer resolution and directly correlate this roughness with device performance. We have developed a method that allows us to measure the sidewall roughness of waveguides made of any material (including dielectrics) using the high resolution of atomic force microscopy. We illustrate this method by measuring state-of-the-art photonic devices made of silicon nitride. We compare the roughness of devices fabr…

基于图像处理的晶圆级波导侧壁粗糙度散射损耗表征

Wafer-scale waveguide sidewall roughness scattering loss characterization by image processing

本文通过二维SEM图像处理评估波导侧壁粗糙度，结合Payne模型估算散射损耗，在633 nm处实现0.075 dB/cm的可见光最低损耗，并验证了边缘检测的100%成功率。

Effects of boundary roughness on a Q-factor of whispering-gallery-mode lasing microdisk cavities

We perform numerical studies of the effect of sidewall imperfections on the resonant state broadening of the optical microdisk cavities for lasing applications. We demonstrate that even small edge roughness causes a drastic degradation of high-Q whispering gallery (WG) mode resonances reducing their Q-values by many orders of magnitude. At the same time, low-Q WG resonances are rather insensitive to the surface roughness. The results of numerical simulation obtained using the scattering matrix technique, are analyzed and explained in terms of wave reflection at a curved dielectric interface co…

基于聚焦离子束抛光的优质二氧化硅微盘谐振器优化

Focused ion beam polishing based optimization of high-Q silica microdisk resonators

针对微盘谐振器侧壁粗糙度问题，提出利用聚焦离子束抛光优化制造工艺，显著降低表面粗糙度并提升散射品质因数，为高性能光子器件制造提供新途径。

Are slot and sub-wavelength grating waveguides better than strip waveguides for sensing?

The unique ability of slot and sub-wavelength grating (SWG) waveguides to confine light outside of the waveguide core material has attracted significant interest in their application to chemical and biological sensing. However, high sensitivity to sidewall roughness induced scattering loss in these structures compared to strip waveguides casts doubt on their efficacy. In this article, we seek to settle the controversy by quantitatively comparing the sensing performance of various waveguide geometries through figures of merit that we derive for each mode of sensing. These methods take into acco…