Spectrally resolved near‐field mode imaging of vertical cavity semiconductor lasers

The transversal mode properties of vertical cavity surface emitting lasers (VCSELs) are studied by spectrally resolved scanning near‐field optical microscopy. In contrast to classical optical microscopy techniques, our method is able to simultaneously decompose lasing transversal modes by their wavelength with lateral superresolution. As the tip‐sample distance is controlled by the well‐established shear‐force detection, additional topographical information showing the surface structure of the laser is provided. Therefore, near‐field spectroscopy allows the detailed analysis of the spatial light distribution emitted by the laser with respect to the current injection contact, making it a promising tool for the characterization and optimization of VCSELs.