190119 Greatly Enhanced Photothermal Nonlinearity in a Silicon Nano-Resonator

Title:
Greatly Enhanced Photothermal Nonlinearity in a Silicon Nano-Resonator

Speaker:
杜懿修 (Yi-Shiou Duh), PhD student, Stanford University

Time:
01/19 (Sat.) 6 pm PST, 7 pm MST, 8 pm CST, 9 pm EST
01/20 (Sun.) 10 am Taiwan

Keywords:
Physics, Optics, Si nanophotonics, Nonlinearity, Mie scattering, Photothermal

Abstract:
For next-generation integrated circuits, photonics may take over electronics to provide fast-speed, low-loss devices. Among all potential materials, Silicon is one of the best candidates owing to its natural abundance and well-established fabrication technique.

The foundation of silicon electronics lies in the nonlinear response from pn junctions, so similar to that, the key element in silicon photonics is optical nonlinearity. However, the optical nonlinearity of silicon is not particularly large. There have been various methods to enhance silicon’s nonlinear response, including microring resonator and photonic crystal, both based on light confinement. In addition, it is also well known that photothermal effect provides the largest third-order nonlinearity in general.

In this work, we show that by amalgamating light confinement based on nanostructure engineering and photothermal effect, seven-order enhancement of nonlinear coefficient over bulk silicon is demonstrated, with mode volume. The experimental nonlinearity from scattering measurement agrees well with photothermal simulation. The exceptionally large nonlinearity not only enables all-optical control with large modulation depth and small footprint, but also paves the way towards integrated silicon nanophotonic circuits.