Waveguide Effect on the Image Formation Process in Near-field Photocurrent Spectroscopy of Semiconductor Laser Diodes

Abstract

Near-field photocurrent spectra of high-power laser diode arrays with different wave-guide characteristics are reported. Subwavelengtb spatial resolution is achieved by using a near-field fibre probe as the excitation source. The effect of the laser diode waveguide structure and of surface recombination processes on the near-field photocurrent image formation is discussed and analysed in terms of a beam propagation model. Experiments on laser diodes before and after accelerated ageing demonstrate the potential of the technique for analysing microscopic defect formation processes in optoelectronic devices.