The first near-field optical imaging of light localization in a GaN nanocolumn system was performed. The sample used was a randomly arranged GaN nanocolumn with high aspect ratio. We attached an InGaN single quantum well at the apex of each GaN nanocolumn as an illuminant antenna and observed luminescence from the illuminant using an aperture-type scanning near-field optical microscope. By this technique, we directly obtained optical images of luminescence and its spatial distribution for the GaN nanocolumn system. These images, along with histogram analysis, excitation wavelength dependence, and numerical calculations, offer evidence of Anderson localization of light.
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