Anomalous excitation-intensity dependence of photoluminescence properties of an asymmetric coupled quantum well structure

We report anomalous emission peak shifts as a function of excitation intensity in photoluminescence spectra from a p-i-n structure where asymmetric coupled quantum wells are embedded in the intrinsic region. Emission behavior can be explained in terms of an anticrossing of quantized levels: this occurs when the energy-band structure automatically becomes flat by means of reduction of the internal electric field by photogenerated carriers. This result may be of significance in creating novel all-optical devices where transition energies are able to be optically modulated.