Time-resolved light propoagation at the band-edge states of 1D Fibonacci quasicrystals

Infrared time-resolved interferometric transmission measurements have been performed on one dimensional porous silicon Fibonacci quasicrystals, obtained by electrochemical etching a p-type Si substrate, to address experimentally the problem of light transport and localization in deterministic aperiodic structures. Coherent beatings, pulse stretching and strong pulse delay on a picosecond time scale have been measured when the laser wavelength was tuned at the one-dimensional band-edge of a 233-layers Fibonacci quasicrystal where quasi-localized states exist. The observation of these dramatic pulse distortion effects demonstrates the selective excitation of very-narrow localized optical modes. One dimensional transfer matrix and scattering states simulations yield the electromagnetic field distribution inside the structure and reproduce these experimental data supporting the general conclusion about the observation of quasi-localized photonics states.