Abstract
We model optical bistability in all-dielectric guide-mode resonance grating (GMR) nanostructures working at quasi-bound states in the continuum (BICs). The complementary metal-oxide-semiconductor (CMOS) compatible material silicon nitride (SiN) is used for the design of nanostructures and simulations. The ultra-low threshold of input intensity in the feasible nanostructure for nanofabrication is obtained at the level of ~100 W/cm2 driven by quasi-BICs. Additionally, the resonance wavelength in the GMR nanostructure can be widely tuned by incident angles with the slightly changed Q-factor that enables the optical bistable devices to work efficiently over a wide spectrum. The impact of the defects of grating that may be introduced in the fabrication process on the optical properties is discussed, and the tolerance of the defects to the optical performance of the device is confirmed. The results indicate that the GMR nanostructures of broadband and ultra-low threshold optical bistability driven by quasi-BICs are promising in the application of all-optical devices.
Highlights
The photonic crystal nanocavity [2,3], Fabry–Pérot cavity [4,5], ring resonator [6,7], and surface plasmon resonance system [8,9,10,11] are employed for the cavities
Numerous works were conducted to increase the Q factor to lower the intensity threshold of optical bistability in guided-mode resonance (GMR), such as the coupled GMR nanostructures of air gaps [21], GMR of double-layer gratings [22], and low-index material embedded in the waveguide layer [23]
The GMR nanostructures consisting of a four-part grating layer of quasiBICs with ultra-high Q factors were investigated for Goos–Hänchen shift and harmonic generation [26,27]
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Numerous works were conducted to increase the Q factor to lower the intensity threshold of optical bistability in GMR, such as the coupled GMR nanostructures of air gaps [21], GMR of double-layer gratings [22], and low-index material embedded in the waveguide layer [23]. Further works are needed to study the optical bistable behavior in the resonance structures of BICs. Recently, the GMR nanostructures consisting of a four-part grating layer of quasiBICs with ultra-high Q factors were investigated for Goos–Hänchen shift and harmonic generation [26,27]. The effects of typical defects of grating on the performance of the optical devices are discussed
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