Imaging near-field transverse modes of vertical-cavity surface-emitting lasers by near-field scanning optical microscopy.

We have characterized the oxide-confined vertical-cavity surface-emitting laser (VCSEL) using short-tip, tapping-mode tuning fork near-field scanning optical microscopy (TMTF-NSOM). The near-field radiation patterns of the VCSEL were measured. By comparing the topographic and optical images, we attribute the asymmetric transverse modes to the geometric defect outside the oxide aperture. We also performed spatially resolved spectroscopic imaging over the surface of the VCSEL by coupling NSOM to a spectrometer.