Enhanced optical bistability in slotted photonic crystal structure for microwave frequency generation

Abstract

Abstract This study proposes a novel silicon nanocrystal SiNC/SiO $${}_{2}$$ embedded slotted photonic crystal nanocavity employing precise width modulation to explore optical bistability and self-pulsing behavior for microwave signal generation. The designed cavity achieves an ultra-high quality factor (Q) of $$2.15 \times 10^6$$ and a low modal volume of $$0.18 \, \mu m^3$$ . Theoretical modeling incorporating Kerr nonlinearity, two-photon absorption, and free carrier effects is used to analyze the bistability response. Simulation results reveal a low threshold power of $$2 \mu W$$ for optical bistability under a − 20 pm detuning condition. Additionally, the cavity demonstrates microwave frequency generation through self-pulsing oscillations, with a fundamental mode and observable second harmonic at 21.34 GHz. Fabrication tolerance is also evaluated, showing that the design sustains performance with up to 9% randomness in hole radii, 12% in x-position, and 20% in z-position of air holes. These findings confirm the feasibility of the proposed structure for low-power, high-frequency integrated photonic applications.