Near-field modulation of AlGaInP laser diode emissions by an aperture probe of near-field optical microscope

In situ emission profiles of AlGaInP multiple quantum well laser diodes (LD's) observed by a near-field scanning optical microscope (NSOM) aperture probe shows a single broad elliptic profile similar to a far-field observation, whereas the local emission spectrum was different depending where the aperture probe was placed within the emission profile. This observation suggests the existence of a near-field coupling between the aperture and the LD cavity, which might modulate the lasing wavelength among the longitudinal multimodes determined by the LD cavity length.