Ultrafast pulse propagation and spectral broadening in metal-dielectric 1D photonic crystal

Abstract

A huge spectral broadening of a femtosecond laser pulse after propagation through a very thin (∼1 μm) one-dimensional (1D) metal-dielectric (MD) photonic structure is reported. The 1D MD photonic structure, (Ag/SiO2)4, fabricated on a glass substrate, consisted of 4 bilayers of silver (Ag) and silica (SiO2). The enhancement in spectral broadening is resulted from enhanced third-order nonlinearity (χ(3)) induced by Fabry–Pérot coupled-cavity effects. The direct experimental observation of supercontinuum generation (SCG) is corroborated theoretically by solving the modified nonlinear Schrödinger equation (NLSE). The numerical modeling delineates that the generation of the enhanced supercontinuum is due to the interplay between different orders of dispersion and nonlinear effects. The presented results may lead to the realization of compact on-chip stable supercontinuum sources for vivid applications in ultrafast optics and photonics.