Optical Bistability in Nanosilicon with Record Low Q-Factor

We demonstrated optical bistability in an amorphous silicon Mie resonator with a size of similar to 100 nm and Q-factor as low as similar to 4 by utilizing photothermal and thermo-optical effects. We not only experimentally confirmed the steep intensity transition and the hysteresis in the scattering response from silicon nanocuboids but also established a physical model to numerically explain the underlying mechanism based on temperature-dependent competition between photothermal heating and heat dissipation. The transition between the bistable states offered particularly steep superlinearity of scattering intensity, reaching an effective nonlinearity order of similar to 100th power over excitation intensity, leading to the potential of advanced optical switching devices and super-resolution microscopy.