Simultaneous observation of extended and localized modes in compositional disordered photonic crystals

Mixed photonic crystals (PCs), the photonic equivalent of semiconductor alloys, are ideal for use in investigating various phenomena occurring in disordered photonic systems. In the present study we fabricated highly disordered two-dimensional PCs, using a wafer-bonded InAsP/InP multiple-quantum-well slab, and examined the resultant photonic resonant modes by determining the spectrally and spatially resolved emission properties. We observed that new localized photon modes formed in the disordered PCs, which are in good contrast to the spatially extended band-edge modes associated with PCs having translational symmetry. Computer simulations confirmed the existence of such localized photon modes in the disordered PC structure.