Thermally-induced nonlinear optical properties near the band edge of one-dimensional Si/SiOx photonic crystal

Abstract In this study, the thermally-induced nonlinear optical properties, near the band edge of one-dimensional Si/SiOx photonic crystal, were investigated. The crystal was fabricated with alternating layers of silicon and silicon oxide, deposited using reactive magnetron sputtering. The fabricated sample showed a stop band, centered at 1050 nm with 400 nm range. The nonlinear optical properties were obtained using standard z-scan technique, stimulated by cw laser system. In this regime, the crystal's periodic structure was approximated with an effective uniform medium. When the pumping wavelength was near the band edge of the photonic crystal, transmittance enhancements at low input powers were observed. At higher input powers, reverse saturable absorber behavior became dominant. The analysis of the nonlinear processes based on resonant heating and increase in light absorption near the band edge is presented.