Spectral mapping of multimode vertical-cavity surface-emitting lasers bynear-field scanning optical microscopy,

摘要

Abstract: We have studied the spatial and spectral characteristics of vertical-cavity surface-emitting laser emission using near- field scanning optical microscopy. We report the multi- transverse-mode characteristics of 15 $mu@m diameter proton- implanted 850 nm devices used in a 2 Gbit/s multimode fiber- optic links. Spectrally resolved and integrated intensity scans over a 20 $MUL 20 area were performed. The intensity of each resolvable transverse mode was integrated and its wavelength range false-colored at each scan position. The resulting composite image displays relative intensity and spatial distribution information for each transverse mode. Correlation with the shear force data allows mapping of the optical distributions to topographical features. Lasing filaments were observed at high drive currents. Gain competition among spatially overlapping transverse modes was observed while spatially isolated modes coexisted without competition.!16