All-optical tunable transmittance in a 1D nonlinear ternary photonic crystal with graphene-oxide nanofilms

— In this paper, we investigate the dynamic tunability of light transmittance in a one-dimensional photonic crystal incorporating nonlinear (NL) Kerr nanofilms of graphene-oxide, focusing on the telecom wavelengths. The linear transmittance spectra reveal the existence of perfect transmittance resonance (PTR) at an incident wavelength of 1540 nm, with maximum electric field enhancement of approximately 11.2, resulting from the interaction between the incident light and the photonic bandgap of the structure. Once the high-intensity continuous-wave pump laser is normally incident on the structure, the linear PTR is reduced, accompanied by a decrease in field enhancement. Notably, as the intensity rises, the transmittance peak wavelength is red-shifted about 5 nm per 100 MW/cm² of input intensity, accompanied by strong resonance bending and the enhancement of weak off-resonance linear transmittance, due to the NL Kerr effect. Moreover, we observe S-shaped bistable transmittance behavior when the structure is excited at off-resonance wavelengths of 1545 nm and 1548 nm. At 1545 nm, the maximum bistability contrast is approximately 0.86 near an input intensity of 100 MW/cm², while at 1548 nm, it reaches about 0.95 near 157 MW/cm². These findings can provide a suitable platform for designing intensity-dependent optical switches and bistable optical devices within the telecommunication wavelength region.