Photothermal bistable scattering from low Q-factor amorphous nano-silicon resonator

Kentaro Nishida^1*, Po-Hsueh Tseng¹, Yu-Chieh Chen¹, Pang-Han Wu¹, Chi-Yin Yang², Jhen-Hong Yang³, Wei-Ruei Chen³, Olesiya Pashina⁴, Mihail Petrov⁴, Kuo-Ping Chen⁵, Shi-Wei Chu^1,6,7

¹Department of Physics, National Taiwan University, Taipei, Taiwan
²Institute of Imaging and Biomedical Photonics, National Yang Ming Chiao Tung University, Tainan, Taiwan
³Institute of Photonic System, National Yang Ming Chiao Tung University, Tainan, Taiwan
⁴Physics and Engineering Department, ITMO University, St. Petersburg, Russian Federation
⁵Institute of Photonics Technology, National Tsing Hua University, Hsinchu, Taiwan
⁶Molecular Imaging Center, National Taiwan University, Taipei, Taiwan
⁷Brain Research Center, National Tsing Hua University, Hsinchu, Taiwan

* Presenter:Kentaro Nishida, email:knishida@phys.ntu.edu.tw

Optical bistability is fundamental toward key applications such as all-optical switching with high modulation depth and super-resolution optical imaging. However, the requirement of high-Q cavities has been a long-time bottleneck in reducing the cavity size, and thus restricted the application to the nanophotonic device. In this work, we discovered a novel optical bistable state in a single silicon nanoparticle with a record-low Q-factor < 10 and cavity volume size of 10-3 μm3. In order to relax the requirement of the high-Q cavity, we utilized the giant optical nonlinear responses in silicon nanocuboids through the interplay of Mie resonance and photothermal effect. We theoretically revealed that the existence of photothermal optical bistability in amorphous silicon nanocuboid through coupled electromagnetic and photothermal simulations. We also experimentally confirmed the optical bistable scattering response manifested by an abrupt super-linear jump of scattering intensity with hysteretic switching.

Keywords: silicon nanostructure, photothermal effect, optical bistability, nanophotonics, Mie resonance