Propagation of ultrashort nonlinear pulses through two-dimensional AlGaAs high-contrast photonic crystal waveguides

Abstract

The propagation of 120-fs laser pulses through nonlinear waveguides with embedded high-contrast, two-dimensional photonic crystals was studied. Each AlGaAs waveguide fabricated upon a GaAs substrates contained a region of deeply etched air holes in a triangular lattice to form the photonic crystal. In transmission, a photonic bandgap was formed with a short-wavelength photonic bandedge at 925 nm from a 270-nm period lattice in the Γ–K orientation. Pulse propagation was highly nonlinear, with both strong optical limiting and spectral narrowing. These effects arose from the waveguide rather than from the photonic crystal. Nonlinear effects were simulated theoretically, with good agreement with the data, by consideration of the effects of two-photon absorption and self-phase modulation on chirped incident pulses.