Optical field enhanced nonlinear absorption and optical limiting properties of 1-D dielectric photonic crystal with ZnO defect

• 1-D photonic crystal with ZnO defect layer was fabricated by rf sputtering technique.
• NLO coefficient of the 1-D PC is 4 times higher than that of a single layer ZnO reference.
• The optical limiting threshold of the photonic crystal is found to be 0.74 J/cm2 @ 532 nm.

We report on optical field enhanced nonlinear absorption and on the optical limiting properties of a 1-D photonic crystal with ZnO defect, fabricated by rf sputtering technique. The structural properties of the photonic crystal are studied using scanning electron microscopy (SEM) images. Light transmission spectroscopy measurement shows a broad photonic band gap with a defect mode. Open aperture Z-scan measurement with 532 nm pulsed laser illustrates a four times enhancement in the nonlinear absorption coefficient, due to local field enhanced two-photon absorption in the photonic crystal structure with respect to the single layer of ZnO reference. The enhancement of the nonlinear absorption in the photonic crystal, due to the strong confinement of the optical field around ZnO defect layer, leads to an optical power limiting behavior in the photonic crystal. The limiting threshold of the photonic crystal is found to be 0.74 J/cm2 @ 532 nm with 6 ns pulse width, 10 Hz repetition rate.

1-D photonic crystal, constituted by a ZnO defect layer inserted between two Bragg reflectors consisting of 21 alternating SiO2/TiO2 layers, fabricated by rf sputtering technique. The dotted data represents the output fluence of the 1-D photonic crystal, as a function of the input fluence @ 532 nm. The optical limiting threshold is 0.74 J/cm2. Solid line represents the linear transmittance of the 1-D photonic crystal.Figure optionsDownload high-quality image (270 K)Download as PowerPoint slide