Near-field scanning optical microscopy of indium gallium nitride multiple-quantum-well laser diodes

Near-field scanning optical microscopy is used to image electroluminescence from three and ten quantum-well (QW) indium gallium nitride based laser di odes. Facet cross sections are imaged with a spatial resolution of <100 nm, below and above the lasing threshold. Observation of spatially resolved sp ectra near the active region reveals compositional fluctuations as well as absorption and reemission of the lasing mode. Single-mode emission is obser ved for narrow (3 and 5 mm wide) 3 QW laser bars. Near-field measurements s how a relationship between modal emission, waveguide structure, and lateral device size. (C) 1999 American Institute of Physics. [S0003-6951(99)02016- 1].