Optical Bistability in a Tunable Gourd-Shaped Silicon Ring Resonator

Abstract

In this study, a tunable gourd−shaped ring resonator is demonstrated to generate optical bistability. The system consists of two sub−rings for a gourd shape configuration with a U−shaped wave guiding pathway. The transfer matrix method and FDTD simulation are used to acquire the spectral characteristics of the system. For the fabricated device, the spectra profile and extinction ratio can be effectively tuned by the microheater above the U−shaped waveguide, which matches with the theoretical results. Due to the gourd structure of the resonator, the light waves in two rings can be cross−coupled with each other, and the optical bistability could come out effectively with the change in the input optical power around 6 mW. The presented optical bistability devices have great application potential in optical information processing such as optical storage, switch and logic operation.

Silicon Nanowire-Assisted High Uniform Arrayed Waveguide Grating

“…In order to simulate the performance of the nanowire-assisted high uniform AWG, 2.5D-FDTD (Lumerical FDTD Solutions of 8.9.1584) method was used [ 37 ]. Perfectly matched layers (PML) were used to simulate boundary conditions.…”

Optical Bistability in Nanosilicon with Record Low Q-Factor

“…In this work, we theoretically and experimentally demonstrate optical bistability in a amorphous silicon Mie resonator with the Q -factor of ∼4, and the volume size of ∼10 –3 μm 3 , which are both significantly smaller compared with other representative silicon-based bistable devices made with photonic crystals − or ring cavities, ,,− as shown in the comparison chart of Figure c (see Supporting Information Table S1 for more detailed comparison). We established a photothermal model that explains the emergence of optical bistability, whose underlying mechanism is temperature-dependent nonlinear absorption due to the interplay between Mie resonance and thermo-optical effect, as explained in the following.…”

“…(b) Comparison between silicon ring resonator and our Mie resonator, for the Q -factor ( Q ), the effective nonlinear coefficient ( n 2 ) and footprint size of the structure ( L ). (c) Comparison of resonance Q -factor and normalized footprint over resonant wavelength ( L /λ) for various silicon-based bistable resonators: photonic crystals (orange), ring resonators (blue) and our Mie resonator. ,,− …”

“…For silicon-based optical bistable systems, they typically require high- Q cavities, such as photonic crystals or ring cavities, , whose Q -factors range from 10 3 to 10 6 , as shown in Figure b, to compensate the low Kerr nonlinearity in silicon ( n 2 ∼ 10 –9 μm 2 /mW) . Moreover, in recent years several unique optical effects were suggested in the coupled nonlinear subwavelength nanoresonators and discrete waveguides, such as the solitonic and oscillonic regimes and optical bistability, − but none of them has been demonstrated experimentally due to the low optical nonlinearity and requirement of strong optical field.…”