Room-temperature excitonic nonlinear-optical effects in semiconductor quantum-well structures

摘要: We review the nonlinear-optical effects observed at room temperature in semiconductor quantum-well structures photoexcited near band gap. A comprehensive discussion of optical transitions these microstructures is given, including excitonic and specific features room-temperature exciton resonances. Experimental investigations using continuous-wave, picosecond-, femtosecond-laser sources are presented. They show extremely efficient nonlinear processes. In case excitations that long compared with exciton-ionization time, induced changes absorption refraction do not depend on wavelength or duration excitation. These only density absorbed photons interpreted terms electron–hole plasma screening filling. contrast, for ultrashort excitation, processes critically excitation wavelength. The selective generation excitons found to produce larger than a same density. This unexpected result shown arise from low gas before it interacts lattice decrease reduced dimensionality structures.