An application of the apertureless scanning near-field optical microscopy: Imaging a GaAlAs laser diode in operation

The imaging of a commercial GaAlAs semiconductor laser emitting at 0.78 μm has been performed by apertureless scanning near-field optical microscopy using a sharp metallic tip. This tip was used as an optical and force probe simultaneously. In stimulated emission, we observed the single transverse laser mode whose dimensions are in good agreement with theoretical results. In spontaneous emission, an optical contrast linked to the known laser layers structure was observed.