Optical Bistability in Nanosilicon with Record Low Q-Factor

Area of Science:

• Photonics and Nanophotonics
• Nonlinear Optics
• Materials Science

Background:

• Optical bistability is crucial for all-optical switching and signal processing.
• Silicon nanocavities offer potential for nonlinear optical applications due to their tunable properties.

Purpose of the Study:

• To demonstrate optical bistability in amorphous silicon Mie resonators.
• To investigate the underlying photothermal and thermo-optical mechanisms responsible for the observed bistability.
• To explore the potential applications of this phenomenon in optical switching and super-resolution microscopy.

Main Methods:

• Fabrication of amorphous silicon nanocuboids with sizes of approximately 100 nm.
• Experimental characterization of scattering response under varying excitation intensities.
• Development of a physical model to numerically simulate photothermal heating and heat dissipation dynamics.

Main Results:

• Experimental confirmation of optical bistability, including steep intensity transitions and hysteresis in scattering response.
• Achieved a low quality factor (Q-factor) of approximately 4 for the Mie resonator.
• Numerical model successfully explained the bistability mechanism through temperature-dependent competition between photothermal heating and heat dissipation.
• Observed superlinear scattering intensity transitions with an effective nonlinearity order of approximately the 100th power.

Conclusions:

• Amorphous silicon Mie resonators can exhibit optical bistability at low Q-factors.
• The photothermal and thermo-optical effects are key to achieving this nonlinear optical behavior.
• The demonstrated steep nonlinearity holds promise for developing advanced optical switching devices and super-resolution microscopy techniques.