<title>AlGaAs-based two-dimensional photonic crystal with defect waveguides for miniaturized ultrafast optical-pulse control/delay devices</title>

Abstract

An AlGaAs-based near IR 2D photonic crystal with an air- bridge structure featuring defect waveguides has been developed. For the sample without defect waveguides, measurement of the optical transmission characteristics in the wavelength ranging form 850 nm to 1100 nm showed a deep bandgap with 30 dB to 35 dB attenuation and transmittance of nearly 100 percent. Optical propagation properties of defect waveguides were obtained by two methods: measurement of transmission spectra at wavelengths ranging from 850 to 1100 nm, and with plan-view observations of the optical beam trace along the waveguide measured with an IR-vidicon camera. 3D FDTD simulations for the band structure and transmission spectra in the air-bridge slab with and without defect waveguides resulted in the appearance of four defect propagation modes specific to the defect waveguide, between two slab modes for the defect-free photonic crystal slab. These defect modes were experimentally identified in the measured transmission spectra. Low group velocity near the band edge was also confirmed through 200-fs pulsed laser- beam propagation measurement.