Propagation properties of light in AlGaN/GaN quantum-well waveguides

The dynamic properties of light propagation in AlGaN/GaN-based multiple-qua ntum-well waveguides have been investigated by time-resolved photoluminesce nce (PL) spectroscopy. The waveguides were patterned with a fixed width of 0.5 mum and length 500 mum using electron-beam lithography and inductively coupled plasma dry etching. Our results reveal a remarkable decrease in the PL intensity as well as an increase in time delay of the temporal response as the location of the laser excitation spot on the waveguide is varied. T hese results can be understood in terms of polariton propagation in the wav eguides. From the time delay of the temporal response, it has been determin ed that the speed of generated polaritons, with energy corresponding to the well transitions in the waveguides, is approximately (1.26 +/-0.16)x10(7) m/s. The implications of these results to waveguiding in optical devices ba sed on the group III-nitride semiconductors are discussed. (C) 2001 America n Institute of Physics.