Near-field scanning optical microscopy of quantum dot broad area laser diodes

Abstract

Near-field scanning optical microscopy (NSOM) studies of self-assembled InAs quantum dot broad area laser diodes (QD-BALDs) with different active layer were performed. The high resolution (< 100 nm) of NSOM provides a detailed mapping of the laser output from the active region. Representative near-field electroluminescence (EL) spectra taken the cross section of the QD-BALD structures below and above the lasing threshold are plotted. Moreover, spatially resolved near-field scanning images of the waveguide are obtained by collecting the EL as the tip is scanned across the surface. Such near-field measurements show a relationship between laser emission and different active layer structure.