Imaging photoexcited optical modes in photonic-crystal cavities with a near-field probe

We report here the scanning near-field optical microscopy observations of photo-excited cavity optical modes. The investigated cavities consist of two-dimensional hexagonal photonic-crystal cavities etched in a III-V semiconductor slab. Under optical pumping, the spontaneous emission of the quantum wells embedded in the photonic-crystal cavities is detected spatially as well as spectrally by a near-field probe. In light of two-dimensional simulations of the photonic-crystal cavities, we detail here the mechanisms that drive the near-field images formation.